How to install Abbott-ERA speedometer correction.

[work2muchplay2little]

Just to reiterate a couple of details; it looks like DC changed the wiring harness from '98 to '99 as the '99 SM shows the two wires (a twisted pair) from the rear axle speed sensor as RD/VT and WT/VT - passing through a single connector on their way to the CAB with the RD/VT terminating at pin 1 and WT/VT terminating at pin 8. The Abbott box on mine is spliced inline with the RD/VT just before its termination to pin 1. The CAB then sends its speedometer signal to the PCM via the OR/WT wire from pin 12.



I don't know if any of this will help, but you may have a bad connection from the speed sensor, to the PCM or perhaps a bad ground at the Abbott box itself. On another note, the other unit available called ?Truspeed? (can't remember exactly) apparently works with rear and four wheel ABS and allows you to set two ratios so you can switch between tire sizes. Good luck!



[Edit: oops, looks like you figured it out while I was typing, everything working OK now?]

 

[Kyle]

Can't find my notes

Sorry it took so long for me to get back, but I did want to close the loop on this. I flat cannot find my notes on my installation of this. We've recently moved and it's got to be here somewhere, just haven't been able to find it in the last few days.



Sorry for promising that and then not coming through. I hope your ground wire solves everything.



If it doesn't, send me an E-Mail (or PM) and we'll get it worked out (I check E-Mail a lot more often then the TDR). I know that we can get through this. Mine's a 99 and your's is a 98, but they can't be that different. I know what it's like being stumped on something like this and I've always gotten great help from the board here. So if I can be of any assistance, please give me a shout.



Kyle

 

[michaelsgreene]

I think I got it now. The thing that threw me was that the color of the wire on pin #1 is not the same as either of the colors that are at the rear diff. All I can figure is that I am now connected between the ABS module and the computer, which really doesn't matter as it seems to work fine,



I got the box all installed and working well, but I think I need to change the ratio by one notch, so I don't put the cover on it yet. I run out of time and leave the project for the night.



Next morning I come out to drive the truck, late as usual, and there is the little LED, flashing merrily away AND THE BOX IS TOTALLY FILLED WITH MILKY LOOKING WATER. Thinking that the unit is now toast, I turn it over and bang it on the carpet a couple of times to get most of the water out and proceed to drive away. To my amazement the light continues to flash and the speedo works, just the brake and abs lights are on.



Just for fun, when I get home, I removed power, scrubbed the board with a toothbrush and soapy water, then fresh water, then a dousing of contact cleaner and then dried it with a blow dryer.



The ERA seems to work 100%. I still haven't figured out where the water came from. My experience with CMOS has always been that even a stern look was enough to pop something, but either this is a very bullet-proof piece of equipment or I got very lucky.



Oh, well. All is well in ERA land. Thanks again to all that responded.



Michael

 

[enrightkp]

Hey guys,

I have had the Abbott on my '99 since about August of 1999. It has corrected my speedo readings but I always have had 3 symptoms I didn't like:

1) ABS and Brake lights stay on for first 20 or 30 feet after first starting the engine and driving, then shut off.

2) Applying the brakes you could feel the ABS pulsing back on your foot just before you came to a stop, and

3) When in very slow stop and go traffic the ABS and Brake lights would come on and stay on until you shut off the engine and restarted.

Note: I have always run with switch 1, 3 and 4 turned on to boost input and output signals per Rickson/Abbott instructions.



I read the pdf file describing the "fix", went to Radio Shack, bought the 4. 7K resistor and wiring, and did the install. I didn't use the 30 gage wire as the leads on the resistor were long enough to reach the white wire and the R4 resistor.

Now my ABS and Brake lights are off and the speedo doesn't work for the first 20 or 30 feet, then they come on and the speedo works but is not adjusted for the correct speed???????

I have tried it with just switch 1 on, with 1 and 3, with 1 and 4 and with 1,3 and 4 all to no avail. NOW WHAT?????? Remove the resistor and live with the first 3 conditions I described?



Kevin

 

[fest3er]

Originally posted by KPENRIGHT
Hey guys,
I have had the Abbott on my '99 since about August of 1999. It has corrected my speedo readings but I always have had 3 symptoms I didn't like ...

At what speed does the speedo start indicating speed? I'd be willing to bet that the connection from the sensor has resistance in it, dropping hte voltage into the Abbott, which, IIRC, doesn't detect a signal if the input voltage is less than 300mV or so.

I had a similar problem, in that my speedo would not register until 5-6 MPH. And when stopping, the rear ABS would engage, causing a loss of braking from about 3 MPH to stop. Turns out the connection from the sensor was sub-par. I re-crimped it and it's been fine since.

When you installed the pull-up resistor, did you move the Abbott from pin #1 to pin #12? If you did, then the Abbott is not the problem, and you need to look at the connectors on pin #1 again; solder them if necssary. And if this isn't the problem, check the position/spacing of the sensor in the rear diff. It might be too far way from the teeth and not producing a strong-enough signal.

Technical:

The rear wheel sensor produces a sine wave of about 300 mV at around 1 MPH up to abount 2 V at around 30 MPH and above. The Abbott stops sensing a signal when the input drops below about 300 mV.

The CAB is perfectly happy with the standard 2-2. 5 V square-wave output of the Abbott.

The Abbott is *very* happy with the 5 V output of the CAB, and the PCM is very happy with the output of the Abbott. The pull-up resistor is needed in this circuit because the CAB's output is open-collector - that is, it pulls the signal to ground and depends on the other end (normally the PCM) to supply the 5 V 'high' signal.

Fest3er

 

[enrightkp]

Change from #1 t #12?

I did not change the Abbott connection from CAB pin #1 to pin #12 - did I miss something in the instructions? I left the Abbott connected to the same place it has been for the past 3 years.

Also, do you turn switch #3 or #4 on to boost input and output signals?

Thanks for everything,

Kevin

 

[fest3er]

Re: Change from #1 t #12?

Originally posted by KPENRIGHT
I did not change the Abbott connection from CAB pin #1 to pin #12 - did I miss something in the instructions? I left the Abbott connected to the same place it has been for the past 3 years.
Also, do you turn switch #3 or #4 on to boost input and output signals?
Thanks for everything,
Kevin

Hmmm. Seems I need to update the PDF. It *is* clearly titled "Modifying the Abbott Box to Correct the CAB-to-PCM signal". [... ] I have added a warning note stating that the Abbott must be installed after pin 12 once the modification is complete.

Thanks for the heads-up! And my apologies for the confusion.

I believe I leave the switches in the position Rickson specified. 1,3,4 ON and 2 OFF. However, once the Abbott is installed between the CAB and the PCM, the input will not need to be amplified, so turn switch 4 OFF. It shouldn't hurt to leave switch 3 ON to amplify the output, but try it first with switch 3 off; if it works reliably OFF, then leave switch 3 off.

Fest3er

 

[enrightkp]

SUCCESS!

I moved the Abbott to pin 12, turned switch 1 on, went for a drive - no speedometer. Unplugged the Abbott and connected the two wires together (wire from pin 12 of CAB and wire to PCM) and speedo worked just fine. Reconnected Abbott and turned on switch 3 - no speedo. Turned 3 off and 4 on - still no speedo. Turned 3 and 4 on - NO SPEEDO. Turned all 4 switches on - SPEEDO WORKS JUST FINE!

Don't know why but all my switches must be on to make it work. Everything is great, ABS and Brake lights go off immediately after starting the truck, speedo works and is corrected, even have the added bonus (?????) of the speedo working when I am in reverse.

Thanks for the help! I have been just dealing with the lights and the ABS thing for 3 years and it is nice to have everything working the way it is supposed to.



Kevin

 

[Udaloy]

Re: Re: Change from #1 t #12?

Originally posted by fest3er

Hmmm. Seems I need to update the PDF. It *is* clearly titled "Modifying the Abbott Box to Correct the CAB-to-PCM signal". [... ] I have added a warning note stating that the Abbott must be installed after pin 12 once the modification is complete.



Fest3er

Fest3er,



I could sure use that pdf. On one of these posts there's a link for it but it's no longer available. TIA,



Udaloy

 

[fest3er]

Re: Re: Re: Change from #1 t #12?

Originally posted by Udaloy
Fest3er,

I could sure use that pdf. On one of these posts there's a link for it but it's no longer available. TIA,

Udaloy

Seems nothing lasts forever anymore, especially web sites.

Try http://murent.us/abbott-mod.pdf

Hopefully I'll be able to keep this site around a while.

One of these days I'll make some HTML for that site and get all the dieselhead stuff organized... .

Fest3er