Anti-Braking System ??

[MojaveJoe]

That's what I call it anyway.....

I had my front brakes done at an independent shop recently. New rotors and pads. New hub assemblies w/sensors (one was frozen from rusting, allegedly), and new backing plates. Now when I perform a hard braking maneuver the pedal gives me about 75% of the braking grab and power I'd expect, but then the pedal goes hard (no pulsing) and there's no braking increase after that. I actually missed my turn into my housing subdivision once. If a car had been in front of me I would have plowed into it, albeit at a reduced speed. I can reproduce this at any moderate to high speed by just standing on the brake pedal. I would not normally be doing this type of braking but it's scary to know someday my anti-lock braking system will cause an accident instead of protect me from one.

So, Did my mechanic screw up when he did the work above? Or is this normal from my truck?

I understand anti-lock braking systems (generally) but the above events occurred on rough dry pavement with good deep tread on all four tires. Thus, I assume no tire was breaking loose or skidding.

Any and all experiences and suggestions welcome.

(about 180K miles on my 3500 now at 10 yrs)

 

[p-Bar]

If the anti lock was engaging the pedal would have pulsated to stop lock up. Go for a test drive with the mechanic driving should be self explanatory for him.

 

[B.G. Smith]

It sounds like maybe while bleeding the brakes the shuttle valve shifted and shut off the rear brakes, if that was the case though the red light on dash should be on. I had similar experience when the metallic pads first cam on the scene, the ones I got were so hard they didn't have good stopping power. Also could be the booster but yo didn't mention any work in that area. Yo can check the ABS as stated above, easiest way is to find some loos gravel or light dirt road and slam on the brakes. bg

 

[Bob4x4]

Abs DOES not work well on rough surfaces.If I plan on driving hard in the rough I pull the abs fuse

 

[MojaveJoe]

All good advice guys. Thanks Loads.

As for pulling the ABS fuse, is that OK with the on-board computer etc? First time I learned about ABS I was speeding on a one lane gravel mountain road and almost went over the side trying to slow down for a sharp turn. Never have liked it since then. Pretty sure the ABS is working. Not sure the rear brakes are operating right. Lots of stuff to check out, and I will fer sure have my mechanic take it for a test ride, with me as passenger.

Im sure it's not right. Had to slam on the brakes in a carpool lane at 70 mph in downtown Los Angeles 2 years ago. The brakes almost sent all 3 of us through the front windshield, but we stopped with inches to spare, and no one hurt, just a little scared. *L* No way my brakes could do that now. Time to take it back for a 90 day warranty fix.

 

[Prairie Dog]

That's the problem with anti lock brakes, in loose gravel you stop faster if the brakes lock.

 

[AH64ID]

It doesn't sound like anti-lock is your issue, like others have said the pedal will pulse.

It sounds like your brakes weren't bled properly, installation error, or the new pads are not as good as stock.

You may want to check the rotor surface for any grease or other substance left over from install that may effect the braking power. The new rotors may now have been cleaned prior to install.

 

[rscurtis]

Don't rule out the idea that when the master cylinder was stroked into an unused part of the bore that one side of it may not be working.

 

[southernman]

Guys,

I want to share an experience I've had with my 3500 4wd 5 spd truck this past week. As many of you know, we got hammered with snow and ice here in NC recently, and I live on a fairly steep hill, which results in dozens of stranded motorist needing help every year. I typically use my truck to pull my hotrods and chore-type work, so it sits most of the year. I pull my truck out yesterday, and tow stranded cars from in front of our subdivision just to keep the roadway clear - and because my wife had not returned from work yet (took her 4.5 hours to make a typical 20 minute commute), and that's where this story begins.

She calls to tell me she wanted to park at the top of the hill, in a Church parking lot, and for me to come pick her up, which I do. Once she's in my truck, I decide to do a low speed stab of the brake pedal just to see how the brakes react (not realizing yet that my ABS is NOT designed to function like 1500's or passenger cars). Remember, I'm on snow and ice when I jammed the pedal. The pedal went nearly to the floor, with only enough pedal left to engage the front brakes. I made it home, but dollar signs went flying across my face as I started to tally what would require fixing to restore my brakes, which had worked perfectly up until this incident.

So I come home and start scowering the blogs and find the 'off road' crowd encounters similar loss of pedal pressure/travel issues when on uneven, or loose (like gravel), surfaces, which is similar to what I experienced, and it took some digging to discover that this is NORMAL...

So I pull my factory service manual (courtesy of Geno's Garage) and began to read. Turns out, there are two distinctly different versions of ABS on our trucks. The 1500 trucks actually have a system similar to most passenger cars, in that stabbing the pedal results in pulsating the brakes to avoid a major skid. At first, I thought this was the system used on all of our trucks, but that is not the case.

If you own a 2500, 3500, or larger Dodge truck, the RWABS (rear wheel ABS) is a system designed primarily to prevent jack-knifing while under, or towing, a load. This would be the case in an emergency stop scenario where a shifting load, or heavy trailer, would try to lift (unload) the rear wheels (slippage). IF you stab the pedal on a slick surface, the ABS box interprets this just like it would for a panic stop, under a heavy load, and on a good surface. More reading...

The other thing I wasn't aware of is, under normal conditions, the ABS box diverts most of the initial fluid volume to the rear wheels first (for sensing and balance) and to engage the automatic adjusters. Remember, our ABS is designed to counter shifting loads - not routine slippage like passenger cars. I know of others who complain these adjusters don't work, but I chalk that up to a box that may not have cycled through the panic sequence, and/or not stroking enough to perform the function. I don't know that for sure, but I'll elaborate more below.

When the rear wheels start to lock up, the ABS runs a "dump" sequence that, literally, drops pressure to the rear wheel cylinders to permit a 'soft' transition while leaving front wheel braking intact. This 'dump' sequence prevents the REAR wheels from locking, and results in the pedal going nearly to the floor. This is NORMAL according to the DODGE service manual, and I can tell you; as long as you continue to drive in slippery conditions, and use 'routine' pedal pressure, your brake pedal/pressure will not restore itself. The system is designed to automatically reset, but you may need to 'coax' it...

Fast forward to today: The snow and ice are gone from most of the roads, so I decide to take a drive in the truck. I'm thoroughly PO'd as I find the pedal is still stroking near bottom, and it's a challenge to stop with just a slight stroking of the front brakes. Raising the rpm's seemed to help a little; pumping the brake pedal 3-4 times would bring it back to normal; but several seconds later pedals near the floor again. Here's what I did:

With the roads now clear of snow and ice, I drove the truck around the subdivision making repeated, normal, stops. No change. I then drove the truck up to about 30 mph, and stabbed the brake pedal. Still no change. So I repeated the process 2 more times, each time, stabbing the pedal as hard as I could. On the third hit, the brakes were completely restored. Not only were they completely restored, but I had the highest, hardest, pedal I can remember, since the truck was new, and I think this is because the
ABS and auto adjusters were jolted by my simulated panic stops. Anyway, my brakes are working excellent now, and the only thing I can assign it to is the RWABS system had not been cycled over the course of it's life, and my repeated hits on the pedal may have broken the shuttle valve loose and restored it's normal operation.

In summary, guys, if you've experienced a dropped pedal resulting from a panic event, you must get the truck on a dry surface in order to restore normal pressures and function.

While I'm not claiming this is the solution for everyone experiencing this problem, I can tell you it worked for me - and it worked today. Good luck with your brake issues and I hope this bit of feedback was beneficial.

Southernman

 

[MojaveJoe]

Good to know!

Thanks for your research southernman.
I almost got killed on a gravel surface cliff road once when my pedal started shuttering near the floor instead of stopping the wheels from rolling. I did not feel like my 3500 reacted properly to slippery surfaces at that time, and now I know why it never does anything but try to slow you down, a little at a time. It's a poorly thought out design IMO, since most of us are not towing or carrying loads when on ice or gravel. Dodge should build in a selector switch for this function to use for varying operating conditions.

BTW...if you are done with our snow, please send it back to CA, we need the frozen water in our Sierra mtns. :-laf

Try to keep warm,
Joe

 

[cerberusiam]

If you own a 2500, 3500, or larger Dodge truck, the RWABS (rear wheel ABS) is a system designed primarily to prevent jack-knifing while under, or towing, a load.

You evidently have a 2nd gen without 4 wheel ABS. The 4 wheel ABS on the 3rd gen trucks is completely different in its operation.

 

[southernman]

My pleasure Joe, and like I said; it might not address everyone's problem, but I thought it was worth sharing. As the manual, indirectly, states our medium to heavy duty trucks have a "towing" based rear wheel ABS that will make it dangerous to use in off road (loose surface) conditions. Best option is to just slow down on slick (unloaded) surfaces. I also agree that Chrysler should have included a bypass option but I'm pretty sure their reasoning is rooted in liability...

Thanks for pinging me back.

S

 

[southernman]

That's interesting because as I dug further into the whole "4 wheel" versus "rear wheel" ABS, it appears to boil down to the rated load/towing capacity of the vehicle.

A true 4 wheel ABS operates efficiently only when the load distribution is 'standardized' to within ~15-20% of a vehicles gross vehicle weight, and across all 4 corners. This may be why the information I've read validates that 1/2 ton 1500 gas pickups were indeed fitted with the 4 wheel ABS, but once GVW climbs with the higher rated diesel trucks, 4 wheel ABS is no longer recommended. I spoke to a couple of my buddies with '08 and '11 3500's and they said they thought theirs came with 4 wheel ABS, but after checking their manuals responded they were mistaken and have RWABS on their trucks only...Manual states for "heavy duty towing"...

Not arguing here, but what I've found is (and your statement is partially correct), gas trucks got the 4 wheel (light duty) ABS option, and diesels of higher rating got the RWABS. I'm not excluding you may have been able to order a diesel set up that way, but Dodge's standard was, and appears still is, RWABS on these high capacity trucks. I'll keep reading and researching, but I'm pretty sure we're on the same track here...

Southernman

 

[HPSimpson]

I have 1996 Ram 2500HD 4x4 Club Cab that I have the window sticker states under options; 4 Wheel Anti-Lock brakes $ 500.
I have looked on the rear axle several times for RWABS, was never installed, under the hood just left brake master cylinder is the Anti-Lock valves. Several years ago since I tow boat and use in salt water the rear drum brakes were a major problem, I remove drum brakes and removed 60 pounds of case iron and installed disk brakes on Dana 80 axle. Occasionally I do have weak pedal goes to the floor the red brake light and the anti-lock light comes on, next stop after works just fine, only way to get lights out is to cycle the ignition.

 

[southernman]

Thanks HP. From my research, it appears that owners who purchased the 4WABS, did not have RWABS, since the 4WABS uses tone rings on all 4 corners. If you run a code scan you should be able to determine why your brakes are acting up. Sounds like a sensor at the tone ring may be dirty or failing. They're hall-effect and fairly easy to check with a good meter...but I digress.

From an operational perspective, 4WABS is not an "intelligent" system. It measures vehicle speed and pulsates the brakes to compensate for slippage - however - the brake bias is constant (i.e. your front discs will continue to operate at 70-80% bias over the rear wheels even if the rear wheels are not touching the ground). By unloading the rear braking during a "dump" event, the rear brakes are slowly released to resume normal 'tracking', and the front brakes remain functional enough to bring you to a stop. At least that's the concept as I read the factory manual...

With RWABS, there is no ABS connection to the front discs (again, unless it was ordered as an option), and for this reason it's darned near impossible to lock up the front brakes on these trucks (RWABS diverts fluid rearward first). Mine operates this way, and I'm sure most others operate the same way given the posts I've read.

On your 4WABS, under a panic scenario pulling a large trailer, there would be no "dump"sequence in the event your truck started to jack-knife or significantly unload the rear tires, but your combination of speed, weight, and load distribution must be within the 4WABS tolerable limits and therefore works OK. BTW, I'm not advocating one system over the other, but it does appear Dodge's engineers standardized most of our trucks with RWABS, and my post wasn't meant to be all encompassing.

The main reason I posted here was in response to those experiencing a pedal that goes near to the floor.

So, to summarize: IF you have RWABS (sensor mounted on top of the differential), then the "dump" function of your ABS is a potential cause for the pedal going near the floor, as fluid is slowly diverted from the rear to the front wheels anytime it senses the rear wheels unloading (slipping). This is to prevent losing control while in a skid - especially when dragging a lot of weight or a heavily loaded trailer. It's designed to operate this way from the factory, and it is a 'normal' condition. It's also normal for the system to "reset" itself the next time the brakes are applied under normal driving (dry) conditions, but my system did not reset...nor would it reset until I got it on dry pavement and stabbed the pedal hard several times. I could see where some may automatically start the death spiral of replacing parts (I've been guilty of it too many times) and wanted to share my experience.

All of our repairs should be this easy, but once in a while we do get lucky. I hope others do as well...

Southernman

 

[cerberusiam]

IF you have RWABS (sensor mounted on top of the differential), then the "dump" function of your ABS is a potential cause for the pedal going near the floor

Neither of those is strictly true. The 3rd gen ABS is a bit more sophistcated than the RWAL system of the 1st and 2nd gen because it is a 3 channel system that gives 4 wheel anti-skid control. The front wheels are controlled seperately with a channel each and the rears are controlled together on 1 channel. The rears are run from the sensor mounted on the diff so that is not an indicator of RWAL at all.

The pedal going low and hard then not resetting is a RWAL malfunction, that should not happen. The typical problem with the RWAL controllers were sticking and causing this problem. In a CAB controlled system if the ABS faults for signal or mechaincal failure the ABS is disabled, similar to pulling the fuse. If it is a mechanical fault it doesn't reset the braking scheme but that is an abnormal condition that requires attention. Generally a good cleaning of the control block will solve that problem. If it doesn't time for a new one.

As was pointed out above, ABS functions less than adequately on rough surfaces. Corrugated gravels and dirts roads do pose a challenge, yet, for the most part the control is still there. Wheels with brakes locked do not lend thenselves well to obstacle avoidance, ABS pulsed braking does as the steer wheels maintain some control on direction. Definitely works much better on slick roads as there is no way to pulse the brakes with iones foot as fast as the CAB contoller can.

 

[southernman]

I appreciate the feedback, but let's dig a little deeper:

There are two distinctly different braking systems clearly explained in the Dodge OEM Manuals. From my manuals, Chapter 5 page 46 explains the RWAL (Rear Wheel Anti-lock) system and states "...RWAL is standard equipment on all Dodge trucks and full size vans.." and my research tells me that's still true today. While Chapter 5 pg 46 covers RWAL systems, Chapter 5 pg 70 covers the ABS systems (which must be what you have) - and is NOT standard equipment on a heavy duty truck. The 'complex' 3 circuit system you describe is the ABS system and I've read that from the OEM manual - which means it's not the RWAL.

The statement on 'sensor' presence is also not correct. A single sensor/wire monitors the exciter ring on the ring gear, which easily distinguishes a RWAL system from an ABS system, which has 2 wires extending from it's modules central (carrier near the yoke) mounting point, to the ABS sensors and 'tone rings' located at the wheels. Uses tone rings and hall-effect sensors on all 4 corners... If your diff has a module with 2 wires running to each wheel, its ABS - not RWAL.

I, personally, wouldn't own a diesel with 'tone ring' ABS where I towed at, or beyond, the rated limits, just for safety's sake. Now without offending anyone on this topic, I'd be OK with it if I never planned to fully stress the truck limits. From your comments, it appears you're mixing the ABS and RWAL system functionality together, and the Dodge manual clearly shows thats not the case. They are entirely separate/unique systems, each with their own controlling logic/hardware. The RWAL is standard on ALL Dodge trucks and full-size vans, obviously for safety reasons. The ABS, which is an "option", only offers ABS function at each wheel, and incorporates a rear "anti-lock" valve - just like every passenger car running up and down the highway today.

That said, the "Dump" function is a 'normal' function for RWAL braking systems (drops pressure to both rear wheels), with the front brakes used in conjunction with the diminished pedal throw to bring the truck out of a skid, restore stability, and to a stop. With RWAL, it's nearly impossible to make the front wheels slip. I've tried for the past two days and the brake balance is near perfect with the rears locking up just prior to stopping (unloaded on dry pavement). I've already found out what happens on an icy surface (see earlier post).

With ABS, if either rear tire unloads, the CAB will continue to modulate the tire having the most contact with the ground. Now, I've got to ask: If the standard system is configured to dump both rear wheel cylinders in a panic stop (allowing trailer brakes to kick-in and help restore stability), are we to believe the "optional" ABS which dumps only one rear cylinder at at time, is a better system in a (loaded) panic scenario ?

For this reason, I'm not seeing any advantage to the 'optional' ABS system - unless you run empty most of the time, and rarely, if ever, operate at, or above, the trucks rated load capacity. Listen, I've got buddies using 3500 Dodges to tow their damned jet skis and to me, they're just posers, but it's their money, and ABS would be more than adequate for them... I'm not advocating for either system, but once I understood how each functions, I'll stick with my RWAL. If ABS is your cup of tea, and that's your preference, write the check, and do know that I'm just glad to chat it up with fellow Mopar enthusiasts.

Southernman

 

[cerberusiam]

Basically no to everything. Your information is flawed and seriously out of date, about 7 years. Take a look at the top of the page. You are posting this in the 3RD GENERATION FORUM. These trucks have had ABS as standard equipment for 11 years or so. I have no idea what you are using for a source but its wrong.

All the rest of what you are talking about is is specific to the RWAL units found on the 1st and 2nd gen trucks, not ABS as it was different, but RWAL. Your symptoms are typical of a RWAL comtroller failure. They do NOT do that when they arre working correctly. They reset right away. If they don't reset because the valves are sticking you get symptoms like you have. The RWAL when it worked was marginal, when it didn't a total POS. That is why most of them were bypassed and removed becasue they were so unreliable as you are finding out.

The 3rd gens ALL have 3 channel ABS, each front wheel has a sensor and the rear 2 wheels are controlled by the ABS\wheel speed senor on the differential. The ABS sensor sources its signal from a tone ring on the ring gear carrier. All the stuff about a tone ring ABS makes no sense because that is what everything has been for 12 years or so and they work much better than anything you have on your truck. The 3rd gens don't have these problems and if they do the ABS controller is replaced.

Let me post the description for 3rd gen ABS directly from the FSM so you can update your understanding:

The antilock brake system (ABS) is an electronically operated, three channel brake control system. The vehicle has
Electronic Variable Brake Proportioning (EVBP) designed into the system which eliminates the combination/proportioning
valve.
The system is designed to prevent wheel lockup and maintain steering control during braking. Preventing lockup is
accomplished by modulating fluid pressure to the wheel brake units.
The hydraulic system is a three channel design. The front wheel brakes are controlled individually and the rear
wheel brakes in tandem. The ABS electrical system is separate from other electrical circuits in the vehicle. A specially
programmed controller antilock brake unit operates the system components.
ABS system major components include:
² Controller Antilock Brakes (CAB)
² Hydraulic Control Unit (HCU)
² Wheel Speed Sensors (WSS)
² ABS Warning Light

The CAB monitors wheel speed sensor inputs continuously while the vehicle is in motion. However, the CAB will not
activate any ABS components as long as sensor inputs indicate normal braking.
During normal braking, the master cylinder, power booster and wheel brake units all function as they would in a
vehicle without ABS. The HCU components are not activated.
The purpose of the antilock system is to prevent wheel lockup. Preventing lockup helps maintain vehicle braking
action and steering control.
The antilock CAB activates the system whenever sensor signals indicate periods of wheel slip.
The antilock system prevents lockup during a wheel slip condition by modulating fluid apply pressure to the wheel
brake units.
Brake fluid apply pressure is modulated according to wheel speed, degree of slip and rate of deceleration. Sensors
at each front wheel convert wheel speed into electrical signals. These signals are transmitted to the CAB for processing
and determination of wheel slip and deceleration rate.
The ABS system has three fluid pressure control channels. The front brakes are controlled separately and the rear
brakes in tandem. A speed sensor input signal indicating a wheel slip condition activates the CAB antilock program.
There are Two solenoid valves (Isolation and Dump valve) which are used in each antilock control channel. The
valves are all located within the HCU valve body and work in pairs to either increase, hold, or decrease apply pressure
as needed in the individual control channels.
During an ABS stop the ISO valve is energized which acts to prevent further pressure build-up to the calipers. Then
the Dump valve dumps off pressure until the wheel unlocks. This will continue until the wheels quit slipping
altogether.

 

[southernman]

You are right about my posting; I posted here because I figured my Gen 2 event might be shared by others who 'know' Gen 2 drivers and could share the info. I also posted in the Gen 2 section and stated, "I hope I didn't violate policy by posting a Gen 2 issue in the Gen 3 section"...

Also, my post didn't validate RWAL as being 'unreliable'. In fact it was quite the opposite, but I'm not going to rehash it...

Regarding the Gen 3 systems, they're a combination of the two systems we've been discussing, with wheel speed sensors added up front to control front wheel lock-up (which now, also have a 'dump' feature too?). The rear wheel dump function is consistent with the original/old braking systems (exciter ring and one sensor on carrier with feedback to CAB), as your own description above confirms (it's no different, functionally, than the Gen 2). So now that same 'dump' feature has been added to the front brakes... The changes were driven by Dodge after upgrading to 4 wheel disc brakes, making it a hybrid system, merging the old and new technology, which leads me to ask a question: If the 'dump' function/control of the 'old' systems were 'inferior', how did they ever make it into the 'upgraded' brake systems on Gen 3 (and newer?) trucks ?

As for my description on ABS with GEN 2's - it's right from the manual, and there's 2 separate chapters dedicated to each (ref 1996 Dodge Service Manual). I'm not posting to engage in a looping discussion about it. I've got the manual: I've read it; and I'm comfortable with the information and explanation of their design/functionality...

As for reliability, or one system being 'better' than the other, I haven't found that to be true at all. The Gen 3 4 wheel discs definitely have the advantage in braking power (HP), as I've owned one myself, and loved the way the brakes performed, while they were operating normally. However, the net's full of "newer" brake system issues (query on Gen 3's and later) ranging from 'push back' on the pedal relating to defective ABS sensors, to recurring ABS warning lights, and far too many incidents where the ABS reacts to phantom conditions and nearly causing accidents. Gen 3 got better, high tech, brakes, but with it came a whole host of new issues to deal with. I'm happy with my 'outdated' non-ABS brakes, and they work great in my humble opinion - once I understood how they function. I've adjusted my driving accordingly.

I've had my truck since '95, got over 300K on it, and not a single brake part (other than routine maintenance on drums, rotors, shoes and pads) has been replaced. Years ago, I did upgrade the rear wheel cylinders with the GM 3500 wheel cylinders, which have larger pistons. That did improve the response of the rear brakes, but other than that, it's all original. No wheel sensors, no issues with dirt getting between the wheels tone rings and sensors, and no codes being thrown from defective cables and/or sensors.

The incident with my dropping pedal, I believe, was related more to driving habits (not a defective module), and rarely putting the truck in a situation requiring a panic stop (soft pedaling it most of the time), and, as noted, it's operating perfectly normal now. Would I prefer the Gen 3 braking HP over my Gen 2's ? Of course, but there's nothing that confirms one system being more reliable than the other. I cannot get my truck to lock up the wheels under pretty much any road condition, and on dry pavement the brake balance is nothing short of excellent, which means my truck is 'designed' to be anti-locking - without the added complexity, and that's exactly how it performs...

Again, thanks for the chat.

Southernman

 

[cerberusiam]

There is no dump feature that has been added to the 3rd gens. There is no dump feature on an RWAL, you are misunderstanding the operations and the symptoms. The DUMP valve and ISO valve are part of the operationl pieces and do not bleed over into each other to effect the front to rear braking. The proportioning valve is what takes care of that and is a failure point on the RWAL, it doesn't work well because of the drum brakes and their consistency in settings.

Your symptoms you are attributing to dump system are not that, they are directly related to an ABS controller failure in the dump valve due to water or rust contamination. Since RWAL has no proportioning adjustments you get a pedal drop and less braking due to imbalance. Those types of failures are well documented in RWAL and ABS troubleshooting. You have no wheel speed sensors to cause problems because your truck does not 4 wheel ABS. It reads the wheel speed signal from the same place the transmission does and only effects the rear wheels. When you lock the fronts you have no steering where 4 wheel ABS allows obstacle avoidance.

You are trying to force fit the operations of a substandard system onto something that is light years in advance. It actually works consistently where the older RWAL was completely inconsistent. You can deny that all day and it doesn't make it true. The 3 channel ABS is far superior to a single channel RWAL in all aspects, the failures points are somewhat the same but the operations and capability are widely divergent. Of all the 1st and 2nd gen trucks the 3rd gen has been by far less trouble with brakes than any of them when driven over 200k miles. The larger brakes definitely are a bonus but the ABS has been much more predictable and efficient than ANY previous truck in that respect.

Unfortunately, your problems are more from maintenance error than driver error. The brake system has not been maintained as well as if should because you are seeing failure symptoms due to lack of said maintenance. You are lucky it came back, this time. The next time maybe not so lucky. Once you tear one of these things apart and see what is happening and why the theory becomes fact.

Now go lookup the number of problems and failures on RWAL as compared to the 3rd gen ABS. At least 10 to 1 or more incidents if they are still accessible. A large part of the 3rd gen failures can be traced directly to lack of care when replacing the wheel speed sensors, the fact they have 2 more sensors than RWAL does play into it, or not replacing them, and, the insistence that when doing a brake job forcing the fluid back into the ABS controller by compressing the caliper cylinder instead of opening the bleeders and flushing it thru. Yes, a lot of the failures are self induced NOT inherent in the design and operation.

Operator errors and misconceptions about ABS, won't even touch that one. A hand grenade in a fuel tank would make a smaller conflagration.

While it is not illegal to post 2nd gen info in the 3rd gen section, the applicability of the information is in question since the systems are so different. That and a lot of your theories are invalid and information severely dated. But hey, we are still hashing this about tagged on to a 6 year old thread so I guess neither of has anything better to do. :-laf

Keep on keepin' on I say.