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I must have been toasted when I wrote this post 13 years ago.
It is the Airbag fault I was thinking of, not the ABS!
Lol
Originally Posted by Randy V
Once the ABS light is activated, it can only be reset using the Bosch multi-tester (aka Bosch Hammer).
I suggest having the ABS reset by your mechanic or Porsche dealer. If the warning light comes back, then you know it is a recurring problem rather than an anomoly and can then begin troubleshooting.
Hi guys. Need some advice please.
I have an 84 S2 and it does have ABS even though there's no reference to it in the manual. Even looking at an 84 fuse/relay details it doesn't even say which relay relates to the ABS.
I think the CE panel relay is X1.
I located the 2 relays in the front wheel arch.
My issue is that the anti lock light stays on when I start up.
I jumped the large black relay in the wheel arch and as soon as I did that I heard a whirring noise from the pump.
The light remained on.
I can try and jumper the CE panel relay not done that yet.
Does anyone have any other suggestions ?
None of the fuses in the CE panel reference ABS so I'm not sure which fuse it is although they all look fine.
Appreciate any advice, thanks
I'd say check every wire and grommet going to the ABS sensors. The grommets that hold the wires rot and fail, letting the wires drop on the axles, suspension, etc. As soon as there is wear, the ABS light will go on.
Thanks for your quick reply.
What I've read suggested that if the light was on at start up it didn't relate to a wheel sensor but more likely a fuse/relay or pump failure.
I'll re read the whole thread, thanks.
You need full 84 ROW electrical diagrams.
Let me dig back through my stuff and try to find.
You also need to survey the equipment if you haven't already.
For instance, make sure you have the right tooth count on back axles.
That could change if somebody over the last 36 rears switched out the rear axles.
Axles without teeth fit. Axles after 86.5 having later teeth count also fit.
Not necessarily the case for your car, but stranger things have happened!
84 cars were the first with ABS, it was optional, and so parts cross referencing would have been a crapshoot.
I sold my 84 ROW to Ed S. a few years ago. It had new rear axles, plus a complete 86.5/S4 front suspension swap and big brakes.
So all 4 wheels were converted then to later tooth count and sensors. I didn't complete the swap...it needed the late computer, too, which I shipped with the car.
My only point being that hidden swaps over the years can be challenging when renewing the cars.
Best I can tell it is relay spot XI on 84 ROW.
IIRC short plug Y is the distribution plug, located next to short plug Z in center of CE panel.
The morehouse CD set Roger sells has some brief ABS troubleshooting, plus some short tech description on how the new 84 system works within Electrical Training docs..
That last doc refers you back to Service Tech Info 84 (ROW/EURO) which is one of the few missing from the collection in the CD set.
These docs were the 100+ pagers that were text descriptive supplements to workshop manual, issued each year for USA and Euro cars.
Shame the Euro 84 is missing.
I've got it somewhere, will have to dig further.
BTW, do check your back axles, both for teeth. None of my 84 cars, including ROW, had the right axles. Yes, my upgrade swap tale was uncommon, but axle swaps due to clunking CDs are not.
Good luck, I need to travel now, will check back tomorrow to see if anybody has antied-up the right docs to help you.
I got a 1991 S4 and I got the speedo not working and some peoples told me to check the sensor of the ABS on the front left wheels. I check and the sensor work. I switch with the sensor from the other side
who also test good and still no speedo.
Any body have any idea where to go from there?
Test the computer controller. you will need a helper to spin the wheel.
So you will have an idea where to look
NEXT
I would suggest to inspect all of the sensor wires and remove every sensor to clean the ends,
its probably time for this service.
refit the wires and sensors,
NOTE inspect the grounds at each wheel .
also clean the ground points in the spare tire well these will be the fat brown wires.
Retest the sensors at the computer connector once everything has been refitted
@Mrmerlin
I just recently posted on another thread about my intermittent ABS issue… quick reminder: ABS passes initial check, then after I begin to drive sometimes the warning comes on, sometimes it doesn’t, and sometimes when it does come on I can dismiss it with the “!” button and sometimes I can’t.
So assuming I want to run the tests you mentioned here, can you give me a step by step on spinning each wheel to test? I will admit, the electrical stuff isn’t my strong suit. But I have a voltage meter, lift, and can get a buddy to spin each wheel. I’m assuming with all wheels off the ground, I need the car in neutral? Is the car running or just on accessory? And where am I checking for signal, at the brain? At the wheel sensor? Both? What kind of read out am I looking for on the voltage meter? Etc.
Last edited by Propermiles; Sep 29, 2024 at 07:51 PM.
well since its an intermittent issue first would be to inspect and clean and put deoxit 100 on all the wire connections,
then test the system .
verify the grounds are also good at each hub and in the spare tire well
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