Problem -- Correcting the speedo for large tires with 4W-ABS.

[Archive]

OK guys -- in case you haven't heard, there is a problem out there we need to put our collective heads together and solve. I am running the 19. 5s on my future truck and with the 4 wheel ABS, the Abbott pulse ratio adapter won't work right.

The Abbott was designed for other purposes and came in handy when needing to fix the tire size issue on trucks with the speed sensor in the rear end ----- BUT, it is my understanding that with the 4W-ABS, there are also sensors in each front wheel. Therefore the Abbott only gets the rear sensed speed and the trucks computer flags it as an error. Problems range from a dash warning light to problems with the activation of the ABS.

Now I could just run with the Speedo off from actual, but I prefer to correct it, if I can.

Anyone found a solution yet?
Any electronis types out there want to tackle this?
Anyone know of another product that is available?

Go team GO!


------------------
Rob Spading -- TDR Webmaster

Already sold my ..... 1996 3500 ... On order -- 2001. 5 ETH/DEE, 3500 QC, 4X4, SLT, Black/Agate, LSD, 4:10's (will be running 19. 5's), AirDam, Camper, Keyless, Fogs, TTow Mirrors, Infinity, Steering wheel controls, Pwr Seat, rearseat storage, Tow, travel/convenience.

 

[Archive]

Don't know exactly how these work but, in general, why can't you just correct the signal going to the speedo/odo and leave the rest alone? After all, do you really car if the computer thinks you're going 65 when you're going 75? You just want the gauge to read 75 right? Leave the signal alone that goes from the speed sensors to the computer and just correct the signal that goes to the dash.

Don't know what this signal is, but shouldn't be too hard to figure out.

 

[Archive]

The expense of this idea might eliminate it, but could you run three Abbotts. One for the rear sensor and one for each front wheel sensor. As long as they were all set the same, would that work? I realize this is not a practical approach, but I am curious.

One other thing to consider, your 01' comes with bigger tires stock than your 96' did, so the error on the speedo would be less. What is the diameter of your 19. 5 setup?

------------------
99'2500 SLT QC LB 4x4
white/agate, 5spd, trailer, camper, 3. 55LSD, 241HD, cab lights, 3500 tailgate lights, mopar mud flaps, luverne SS nerfs, diamond plate rails, Weatherguard box, Banks 4inch, Isspro Boost/EGT gauges(pre), 265 BFG KO's, ... more to come

 

[Archive]

My $. 00002 - If the puter was reading all 3 sensors then they have to come together somewhere for input to the dash. It would make sense to change the output of the 3 sensors at the point where they come together.
I dont't think changing just the dash is a good idea because you are not correcting the ABS part of the system and might send false signals to the puter which could activate the ABS at the wrong time.

 

[Archive]

Hey Rob,

Have you considered just removing the speedo asm, popping the needle off at 0 MPH and putting it back on around 10MPH? This sounds like the easiest fix. It won't help your odometer but it WILL re-adjust your speedo.

Mick2500
<font color=blue>

------------------
2001 2500 ETH/DEE, QuadCab, 4X4, SB, LSD, 3. 54, SLT+, Sport, Intense Blue PC/Agate, Tow Package, Camper Package, 'DC' Bed Cover, Sliding rear window. Ordered 5/01/00... Cancelled 5/30/00... re-ordered 6/02/00... Cancelled again by DC 6/05/00
Gauges (EGT/Boost) and A-Pillar mount Here, 4" Exhaust, Here.
UPDATE!! Re-ordered 7/7/00..... Finally a new VON,
Status BX 7/11/00,
Status D 7/12/00 (I now have a VIN)!!

 

[Archive]

Rob had the same trouble you have had in oct. 99 worked with engineers at Abbott for several weeks trying to figure it out had me splice this wire then that wire which I had a hard time doing on a new truck with no luck never did get it to work right luckly I bought it from a good dealer and he refunded my money and gave me a discount on another order (JRE)

 

[Archive]

Originally posted by Rob Spading:
OK guys -- in case you haven't heard, there is a problem out there we need to put our collective heads together and solve. I am running the 19. 5s on my future truck and with the 4 wheel ABS, the Abbott pulse ratio adapter won't work right

One solution is to put an Abbott box on each sensor. But that is prohibitively expensive. And the Abbott box probably does not correct the signal properly; the sensor signal is differential, while the EPRA is single-ended.

I'm working with Dan Richter on this; he's looking for a better solution as well. I'm getting close to a solution. My Abbott box seems to interfere with the ABS function on my RWAL '98. Talking to my brother, who knows electronics, he thinks I should be able to put the Abbott box in series with the signal line going from the CAB to the PCM. This might work, and it might not.

If it works, nothing else will be needed. If it doesn't, my brother will design a mod for the EPRA that will feed a nice sinusoidal signal to the EPRA, and convert the EPRA's output to the same kind of square wave the CAB sends to the PCM.

Alternatively, if the box is simple enough, my brother might design and manufacture a new box that will properly correct the signal from the CAB to the PCM, thus not affecting the signals the ABS receives from the wheel sensors. To do that, he would need some idea of the market size (to determine profitability). To this end, if you are interested in a box that works with our Dodges (either a modified Abbott box or a new design), send me an email (mailto:neal. p. murphy@alum. wpi. edu). Granted, this 'market survey' covers only '98 to current diesel Dodges, but it would give some indication of the total market.

In the next couple days, I will know if the EPRA works on the CAB-PCM line. If not, my brother may have a solution in a few weeks.

We're working on it. But progess has been a tad slow - DC really don't want to part with the necessary signal information. But things seem to be coming together now. I'll post again in a few days.

Fest3er

 

[Archive]

is it not possible to change the tire revs in the ecm , i had this done on my 98 gasser by the dealer ? cost was 1 hr of diagnostic time even though it took 5 minutes.

 

[Archive]

I dont understand I have a 1999 4WD and have had the Abbott hooked up 1 year 2 months and knock on wood have not had a problem at all. The speedo is dead on and works great.

 

[Archive]

Bakwudz, Does your truck have 4 wheel ABS or rear wheel ABS. If you have 4 wheel ABS, I would like to know how you have your ERA hooked up. When I installed mine the speedo was dead on, but it was tripping my ABS. Abbott was kind enough to let me try another ERA, and then refunded my money when I had the same problem with the second ERA. They do stand behind their product. -Glen

------------------
1998 12 valve 2500 Quad Cab, A/T, 4. 10, Deep Amethyst, 4. 5" Skyjacker Double Flex lift kit, 36. 0"x14. 5"x16. 5" TSL Super Swamper radials on 16. 5"x9. 75" Weld Typhoons, Speedliner spray in liner, Raven high rise cap, J&J stainless steel Nerf-N-Steps, 4" Jardine exhaust

 

[Archive]

Thanks for the input so far.

bakwudz -- The problem is not with 4WD but with the 4 wheel ABS set-up.

Mopar-muscle -- I believe that reprogramming the ECM "might" be possible. I have heard several people say that it used to be limited to available stock revs only. Also have heard that it can't be done anymore. Anyone know for sure?

fest3er -- keep up the good work. I had heard that someone was actively seeking a solution, but didn't know who. Count me in for one, unless something changes my mind -- link an ecm reprogram.

 

[Archive]

Rob, I have had my Abbott ERA installed for over 1. 5 years and 25k mi. on my '98. 5, 4WAL brake equipped Ram. In all this time I have NEVER received any fault due the installation of the ERA.

------------------
'98. 5 2500 QC 4x4, (BLACK) SLT Sport, ISB, LWB, 3. 54 LSD, A/T, Glasstite Vision II canopy, Line-X spray in liner, 285/75R16 BFG A/Ts on 16x8 M/T Challengers, Warn 4X Boards, Mopar fender flares, front and rear NW Custom stainless steel/rubber mud flaps, Mag-Hytec diff. cover and trans. pan, Edelbrock IAS shocks, Mopar tow hooks, Reese Titan V hitch, Jordan Research Ultima 2020 trailer brake controller, VDO Vision gauges, '00 Sport grille, '00 Sport headlights with PIAA Super White 9007/9004 bulbs, 4-2-7+4 Brite-Box, PIAA Dual Sport 900 auxiliary lights, BD exhaust brake and TorqLoc, Prime-Loc fuel filter relocation kit, Bosch 275 hp. injectors, VA CPC, DD Boost Module, Banks Stinger wastegate actuator, BLACK '00 valve cover, Banks Stinger 4" dia. stainless steel exhaust system, BD LV V-10/Cummins hybrid TC and valve body, BD modified transmission front pump and PressureLoc, Air Bulldog induction hood (with NACA ducts), plus many other trick modifications

[This message has been edited by John (edited 07-29-2000). ]

 

[Archive]

Rob, I was talking to the guys at Rickson Truck Accessories about this a while ago. They advised that the computer could be set for an alternate tire size using a DRBIII scan tool. The alternate tire size would have to be entered as revolutions per mile. This would easy to figure out. Mark a tire with chalk, and measure the distance it takes for one revolution. Then divide into 5,280 ft. , hence revolutions per mile. I haven't tried this as I don't trust the lovely Dodge dealers in the area. If anybody has any experience with this I would definitely be interested. -Glen

------------------
1998 12 valve 2500 Quad Cab, A/T, 4. 10, Deep Amethyst, 4. 5" Skyjacker Double Flex lift kit, 36. 0"x14. 5"x16. 5" TSL Super Swamper radials on 16. 5"x9. 75" Weld Typhoons, Speedliner spray in liner, Raven high rise cap, J&J stainless steel Nerf-N-Steps, 4" Jardine exhaust

[This message has been edited by Glen Pratt (edited 07-26-2000). ]

 

[Archive]

If anyone finds a solution to this dilemma, make sure to post it conspicuously. I'm sure there are alot of us that are tired of resorting to algebra to drive our trucks. I can't seem to find a decent formula for correcting my speed for the larger tires. By my calculations, at 65 mph, I should be reading somewhere around 58. 4 but am actually reading 54mph. ARRGGHHH! Let me illustrate:

The formula is:
(old tire size) X (actual road speed) / (new tire size) = (actual speedometer reading)

Therefore:
31 X 65 / 34. 5 = 58. 4

Why have I found that my speedo reads 54mph when I'm doing 65?

Also, I haven't yet figured out the formula for correcting the odometer reading. Any ideas?

------------------
Y2K 2500 4X4 5-spd Reg cab
Dark Garnet Red
Towing/Camper/Snowplow pkgs.
-------------------------
Already added:
Blaupunkt AM/FM Cass. & 12 CD Changer, Diamondplate running boards, Clearance and Tailgate I. D. lights
2" Daystar Front Coil Spring Spacers,
35x13. 50R16 M/T Baja Claws,
16x8 black Rockcrawler wheels,
Bushwhacker Extend-a-Fender flares.
-------------------------
In the future:
A big honkin' chrome rollbar!!!! Oh, and more power too!

 

[Archive]

DixieDawg, Divide 65mph - your actual speed by 54 mph - your speedo, 54/65=1. 203703703. Then multiply this number by your odometer/trip meter reading and you will get your correct mileage. This is what Abbott tells you to do to set the dip switches on the ERA to set the speedo correction. I've been doing this to check mileage since I sent my Abbott ERA back. 4 wheel ABS and the Abbott ERA don't work. -Glen

------------------
1998 12 valve 2500 Quad Cab, A/T, 4. 10, Deep Amethyst, 4. 5" Skyjacker Double Flex lift kit, 36. 0"x14. 5"x16. 5" TSL Super Swamper radials on 16. 5"x9. 75" Weld Typhoons, Speedliner spray in liner, Raven high rise cap, J&J stainless steel Nerf-N-Steps, 4" Jardine exhaust

 

[Archive]

Regarding calculating MPH: Check this website http://www.powerdog.com/tiresize. cgi

Enter your old tire size and your new tire size. Part of the program output is tire revs per mile. It will also show the difference in percent. Take that percent as a decimal and add 1. 0 to it and that will be your speedo correction factor. Example: Increasing from 245/75-16 to 285/75-16 is 7. 8% difference. Correction factor is . 078 + 1 = 1. 078. If your speedo shows 65 MPH your really going 65 x 1. 078 = 70 MPH with the larger tires.

------------------
Wait'n for my 2001 2500 QC, SB, 4x4, ETH 6-sp, 3. 54 LSD, SLT++ (everything but those silly looking lights on top of the roof), White over Silver, Tan leather.

 

[Archive]

Anyone have access to a DRB scan tool and can verify that this can still be done with the newer trucks? I will attempt to talk my local Dodge Boys into it, but have heard that they can't or won't do it anymore.

 

[Archive]

Fest3er, count me in on a box as well.

------------------
Randy Richmond, 98. 5 24 valve, 2500, 5 speed, 4x4, 3. 54, LB, QC, Van Aaken CPC, PacBrake, Walker flowthru muffler, Amsoil, running boards, Leer Shell, Metalic Red.

 

[Archive]

Glen, I was told by my dealer (prior to adding my Abbott ERA) that they could ONLY program for an alternate tire size from those offered as OE.

 

[Archive]

My dealer attempted to change computer with the Dodge Scan Tool and it showed only the oem tire sizes 245 & 265. Also had a secton for tire rpm's. They couldn't make requested change after working on it for 45 minutes. Didn't charge me either. (you gotta' love those old timey dealers)
As for tire rpm (revs per mile) most tire dealers have a spec book that gives that info I've looked at Goodyear, Fireston and Bridgestone) The book also provides weight capacity by tire pressure. A big help when both heavy and light!

------------------
Denny