Speedo recalibration parameter.

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I'll be going with taller tires shortly so I stopped by the local Dodge dealership to inquire about having the parameter in the PCM changed to give correct speedometer reading with the new tires. Minus any mass confusion, the tech writer called a mechanic over to answer my querry. In a '99 service manual is a page of tire sizes and parameters for the PCM. It's in the wheels and tires section of the book. He said the parameter is the "revolutions per mile". How much simpler could it be? So if you can calculate revs per mile, that's the parameter the tech needs to write into the PCM. He's going to do mine for the minimum diagnostic charge since there's no flat rate for the procedure. All parameters in any computer have range limits. Don't know what the range is for this parameter but it should allow for sizes we would be using with the exception of "Big Foot".

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98 2500 CC 4X2 12v 5spd 4. 10, -silencer, AFC+20, Edelbrock IAS, VDO gauges
97 Dodge Stratus 150HP
92 Harley Fatboy, Dynojet fuel management, Supertrapp 2-1

 

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Just wondering if you have made your decision while also considering getting that Abbott ERA (electronic ratio adapter) gadget, which allows YOU to alter the signal input to the PCM for speedo and odometer calibration? I am curious about the pros and cons.

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I was told the same thing by the dealer - they could reprogram in the revolutions. Unfortunately, they were not able to make the changes. They couldn't figure it out. It seems that the tires that I had at the time (33") had to low of a number to enter.

I ended up buying the Abbott ERA. It works well and the benefit is that when I changed tire sizes (up to 35") I could adjust it and save the money.

Berserker


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99 2500 QC LB 4x4 Auto, Laramie SLT, driftwood. Cummins 24v w/ 275 HP injectors & Banks Stinger Plus kit, EGT and Boost gauges on A-Pillar mount, Prime-Location fuel filter kit, MagHytec Diff and Trans covers, EZ Change oil drain plug, BFG 35x12. 50x16. 50 MT's, Tuff Country 5” stage II lift-kit, Rhino liner, Smittybilt nerf bars, Warn chrome Transformer brush guard w/Warn12000 winch, Tow Hooks, Xenon fender flares & Abbott Electronic Ratio Adapter. DTT's Valve Body & Torque Converter.

On-Order - PE EZ box.

 

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I corrected the speedo in mine by swapping the driven gear on the speed sensor. Since I have a 5 spd, the shift points are not affected, and I can't see any problem with this method for a manual trans 12 valve. The gear cost around $12. 50 at the dealer. If there is a reason not to do this, I'd like to know. I just checked my '97 shop manual, and didn't see any "revolutions per mile" chart.

Pete

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'97 2500 CC 4X4 5spd Sport
'83 K5 Blazer 350 TBI (ex 6. 2), 39. 5 TSLs, 3" lift, Dana 60/GM 14 blt, Detroits

 

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I installed an Abbott E. R. A. in my '98. 5 Ram over 1. 5 years ago to correct the speedometer when I went to my 285s (from the OE 245s). This has worked flawlessly for me. Abbott even worked up a new ratio that turned out to be exactly right for my application. #ad


[This message has been edited by John (edited 11-09-2000). ]

 

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Originally posted by John:
I installed an Abbott E. R. A. in my '98. 5 Ram... ... . This has worked flawlessly for me. #ad

<font color=blue> Does anybody know whether this Abbott E. R. A. unit has any significant impact on the use of ABS brakes and specifically 4WD ABS systems? I'm looking at the Rickson 19. 5" set-up for next year and there's conflicting information out there so far..... #ad


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JMc

2001 Flame Red Sport 3500 QC, 5. 9L 24v Cummins, 4x4 Auto, 3. 54/LSD, 155 inch WB, Agate leather, Camper Special & Trailer Tow Groups , Sliding Rear Window, WAAG sidetubes with dually kickouts, Line-X UTR Bedliner & underseal, Grover Airhorns, Lance 1130 slide-in Camper, 60 gallon Aerotank, RS9000s, Reese Titan class 5 hitch, Roadmaster XX, in planning stages... . Gauges, Mag-Hytec, Exhaust Brake, Psychotty Air, Prime-Loc, 4" exhaust, Injectors, Rickson 19. 5" wheels, , Bill K. VB & TC.

[This message has been edited by JohnMcIntyre (edited 11-09-2000). ]

 

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JMc

From what I have seen, the Abbott ERA works fine on 4 wheel abs... EXCEPT apparently SOME of the trucks out there will turn on the ABS light on the dash when braking. I think it depends on much you have to correct. The truck I saw that was doing it was 98. 5 with 285x70x16's. Other than the idiot light, the braking and function of the ABS seems normal.

Mine Abbott box works great, but I only have rear antilocks.

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98. 5 2500 QC LB 4x4 5spd, white. BFG 285x75x16
Cummins 24v w/ TST PowerMAX w/EGT and Boost gauges on A-Pillar. VanAaken CPC. K&N In the factory air box. Stock Injectors, Stock Exhaust (complete with rattling baffles in muffler). Re-routed breather stink tube, 2WD-low kit, SnugTop, JJ Stainless Running boards, Tow Hooks, Bushwacker Street Flares, and a Cup Smoothie.
70,000 miles (8/25/00)

 

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I've never been able to sort this issue out. Seems like prior to '98 you made the correction by changing the speedo gear and after '97 you reprogram the ecm. The dealer told me you could only reprogram up to 265's and no larger. Sounds like the Abbott might be the way to go #ad

 

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I posted a question about the Abbott box and 4 wheel abs over on the products forum but didn't get any responses. I have read on other posts that some people are not only having the abs light come on but the abs system is not working properly. I went to Rickson's and they will not install the box on 4 wheel abs systems at this time because of reported problems. They recommended going with 3 boxes and doing the install myself. Gets kind of pricy. You install one for the rear sensor and one each for the front wheel sensors. From what I can tell, D/C can't get the scantool software to change the rev/mile.

Dave.

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99 QC SB 4x4 Auto
Factory Ordered
Most Options

 

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I didn't know the range of the parameter was that limited. Or is it the tech not knowing how to change it or alter from the book? I'm only going to 31" tires so the 265/75 series parameter will work.
The Abbott box at $150 is alittle steep compared to the $45 Dodge wants. The problem with the Abbott box is, 4wheel abs will only tolerate a 5% difference between the two rear wheels and each front wheel speed. Going from 245s to 265s in about a 6-7% difference. The truck thinks you have poor traction.
Pre-'98 trucks used a plastic gear driven frequency transducer mounted to the side of the tail shaft housing on the transmission. '98 and newer trucks use the abs sensor on the differential. There's a bicycle sprocket mounted between the ring gear and carrier that the sensor reads pulses from. I wish they would have stayed with the plastic gear in the tailhousing. I'm just happy that the parameter can be changed.

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98 2500 CC 4X2 12v 5spd 4. 10, -silencer, AFC+20, Edelbrock IAS, VDO gauges
97 Dodge Stratus 150HP
92 Harley Fatboy, Dynojet fuel management, Supertrapp 2-1

 

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Originally posted by Steve McDaniel:
... The problem with the Abbott box is, 4wheel abs will only tolerate a 5% difference between the two rear wheels and each front wheel speed. Going from 245s to 265s in about a 6-7% difference. The truck thinks you have poor traction. ...

(Allowing that Service Manuals are just plain wrong too often) the SM for my '98 says the 4WAL is engaged only when there is 20%-30% difference in wheel speeds. Thus, it would take 36"-40" tires to interfere with the ABS under *normal* braking using an Abbott box; with tires smaller than that, normal braking would be normal, while hard (panic?) braking would cause the ABS to engage sooner than expected. 4WAL owners have to decide if they can deal with this 'change' in the ABS operations.

I still haven't finished characterizing my '98 and the Abbott box. I've been packing, selling and moving the past couple months, so my investigation of the Abbott box had to be sidelined.

Monday before Turkey Day, I hope to finally characterize the CAB-to-PCM signal and modify the Abbott box to correct that signal. When it works, we'll have a solution that splices in *after* the CAB, thus it will not interfere with the ABS operation at all.

When it finally comes together, I'll work with Dan at Rickson to figure out how to modify a batch of Abbott boxes and make them available to y'all.

Fest3er

 

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Fest3er,

I found a similar statement in the service manual for my 2000 model year, but what I found was phrased differently. My manual says that the 4WAL brakes operate during periods of "high wheel slip. " This is defined as "the point where wheel rotation begins approaching 20 to 30 percent of actual vehicle speed. " This means there would be a 70 to 80 percent speed differential. That means you have even more leeway than originally thought.

I'm glad to hear that you will be working with Rickson on this. I hope to get a set of their wheels and tires when my factory tires wear out. I expect you guys to have this all figured out for me by the time I've used up those tires.

Loren

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2000 Quad Cab, 4x4, short bed, six-speed.
1995 Standard Cab, 4x4, long bed, automatic. (soon to be sold)

 

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I thought this thread was history. I went with a set of 31" Continentals. When I got my truck back it had three Continentals and one something else that looked just like a Continental. Honest mistake for the average shop sweeper. So the manager came out and with horror usually reserved for train wrecks, assured me that it would be taken care of and the odd tire could be used at his expense. The fourth Conti would be in in a couple of days. A couple of weeks went by and the story was that with all the Firestone replacements, the Continentals were alittle scarce. That made me feel all fuzzy inside knowing that I paid $80 for the lifetime roadhazard warranty for tires that can't be had in a pinch. That and the 31" Continentals put the rpm at 60mph right in the drone zone with a load. We had a friendly chat and he agreed to take all three Continentals (and that other one) back and I went with four 245/75R16 Michelin LTX M/S raised outline white letter sneakers. Believe it or not, I'm glad to have the rpm back up where it was before. It seems to smooth out above 2100rpm.
The fine folks at the local Dodge dealership were more than helpful and the cost was zilch. However, the parameter for changing the speedo on a 98 isn't in the options. You have to go into the other catagory and create a parameter to correct the speed. More time consuming. 99s at least have a 235/85R16 and 265/75R16 option that'll get you there for 31" tires. Needless to say I wasted their time but I learned alittle in the process.

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98 2500 CC 4X2 12v 5spd 4. 10, -silencer, AFC+20, Edelbrock IAS, VDO gauges
97 Dodge Stratus 150HP
92 Harley Fatboy, Dynojet fuel management, Supertrapp 2-1

 

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So after all the confusion is there any way to change the speedo(safely!) on full antilock brake equipped trucks? Has Abbott or Rickerson figured it out for anyone?

 

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Originally posted by James P Murray:
So after all the confusion is there any way to change the speedo(safely!) on full antilock brake equipped trucks? Has Abbott or Rickerson figured it out for anyone?

The signal between the CAB and the PCM appears to be a plain, simple, TTL-level signal. I need to find a TTL 'output' on the Abbott box that I can route to the PCM. The Abbott box is happy with just about any kind of input signal. Once I find the desired TTL output signal, I should be able to drive the PCM input, thus correcting the speedo/odo *after* the CAB and avoid messing with ABS operation.

The effort progresses, albeit slowly.

Fest3er

 

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I went from the stock 245's to 265's just because the truck looked like a rollerskate. The dealer said their usual reply, "now we can void your warranty" . I left giving them the single finger salute! Im starting to fall back in love with my truck and I dont need the crap Im getting from the local 5 star dealer. Im beginning to become my own warranty station. Ill save my 7/100,000 for when I pitch the trans or when I need another new stereo. Anyway, I didnt notice much diff when I went to the next size up on tire size. Do I need to re calabrate the computer or can I just leave it alone. I dont want the Dodge Fools touching my truck unless its towed in and broke! The only diff I have found is the shift from 1st to 2nd is a little sooner. That I can live with. I guess my speedo is a little slower, but on the bright side, my warranty will last longer! I only have rear anti lock brakes and the intire brake system sucks anyway so that isnt a concern of mine. I would just like to know if im doing any damage to the truck by just leaving it all alone and at the stock settings... Thanks guys

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98 Quad Cab 4X4 Cummins PAID WAY TOO MUCH$$$$$$$$ Automatic Totally loaded Minus fuel sender plus right brake pull, no extra charge! K&N filter, Line X spray on liner that chips everytime I haul something, WORTHLESS CHRYSLER 7/100,000 WARANTY, First name basis with Enterprise Rent a Car and my local AAA tow truck driver.

 

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I too have been disappointed with the dealer. They told me my tires were too big (approx. 35") to recal. the PCM. SO I have left it alone. I just have to remember 60 is really 66 mph and 70 is 78mph, also when calculating MPG, it appears lower than normal. I have had no ABS flashes.

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99 Ram 2500HD 4X4 Quad Cab SLT Laramie, LWB, 5 Spd, 4. 10 LSD w/Mag-Hytech, Tow & Camper Pkg's, Forest Green, Fog & Clearance Lamps, 3" Stainless steel straight-pipe, PacBrake, Interceptor Bug Shield, Vent-visors, Westin Nerf Bars, Extang Tonneau, Herculiner Bed, Silencer Ring removed, 2" front susp. lift, 315/75/16 Pro Comp A/T's on American Eagles.

 

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phil , they actually can void your warranty as you have altered the mileage reading , i did the same change as you on my 98 ram , first i got the correct speedo gear , when i pulled the sensor from the trans , i found it a bit od that it had wires instead of a cable, it was just a magnetic pickup for a hall effect sensor , parts guy should have picked up on this . i went and talked to service and they were able to change parameter in the computer with the DRB tool , they charged me 60 bucks for a 5 minute ( literally ) job . my speedo read 4 mph higher than i was actually going as witnessed on one of them roadside radar warning signs . go to a different dealer and tell them you just changed the tires .