Problems with PDAS/ABS on 89 C4.
01-21-2008, 03:27 PM
#16
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thanks
First off it's always great to welcome another Alberta Rennlister!
As for the PDAS/ABS issue I just spent the last six months troubleshooting mine and had pretty much done everything - cleaned all the connections in the entire system, replaced relays, topped up fluid, etc... all to no avail. Last month I replaced my coils (thanks Dave
) and haven't had any lights since! Even though the ignition coils and PDAS/ABS controllers are at opposite ends of the cars a bad coil or any noisy part of the ignition system can cause havoc with the apparently sensitive electronics.
Have you tried unplugging one ignition module at a time to see if the car runs rougher or not at all. Running just one coil or the other you might find that the PDAS lights don't come on at all (as I did).
Check out https://rennlist.com/forums/964-forum/375433-what-effect-to-coils-have-on-power.html for good coil pics. If you do disconnect a module be sure that you disconnect the ignition module connector - don't disconnect any of the high tension leads!
Also check out the many threads for PDAS/ABS lights such as https://rennlist.com/forums/964-forum/388825-89-c4-with-interlock-and-abs-warning-lights-and-buzzer.html
Good Luck!
(btw, these cars are scary without ABS in the snow - they still get great accelerative traction but stopping
)
Have you posted any pics of the car yet? It's a Rennlist necessity.
As for the PDAS/ABS issue I just spent the last six months troubleshooting mine and had pretty much done everything - cleaned all the connections in the entire system, replaced relays, topped up fluid, etc... all to no avail. Last month I replaced my coils (thanks Dave
) and haven't had any lights since! Even though the ignition coils and PDAS/ABS controllers are at opposite ends of the cars a bad coil or any noisy part of the ignition system can cause havoc with the apparently sensitive electronics.Have you tried unplugging one ignition module at a time to see if the car runs rougher or not at all. Running just one coil or the other you might find that the PDAS lights don't come on at all (as I did).
Check out https://rennlist.com/forums/964-forum/375433-what-effect-to-coils-have-on-power.html for good coil pics. If you do disconnect a module be sure that you disconnect the ignition module connector - don't disconnect any of the high tension leads!
Also check out the many threads for PDAS/ABS lights such as https://rennlist.com/forums/964-forum/388825-89-c4-with-interlock-and-abs-warning-lights-and-buzzer.html
Good Luck!
(btw, these cars are scary without ABS in the snow - they still get great accelerative traction but stopping
)Have you posted any pics of the car yet? It's a Rennlist necessity.
Thanks for th eadvice. I'm anxious that maybe the two new coils I ordered that I'm picking up today might fix the PDAS. I have same problem as above. Now that I've seen the dirty / broken sensors, I'm going to inspect those too. Intersting thing about my condition, when I wash the engine compartment, lights almost always go out, completely normal operaton til overnight dry out, then back to lights, as above. I'm thinking it may be a rear sensor affected by water creating a good circuit????????????????? I can tell you this, PITA
PDAS/ABS has almost offset the fun of driving, almost.
01-30-2008, 04:16 PM
#17
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A little update: When I pulled the speed sensors out and found one without the nub, I thought that it was broken off. Apparently this is just the newer version of the same sensor, I paid $340.00 to find out that the nub isn't actually supposed to be there, so now I have an extra ABS speed sensor, haha.
I ordered two new coils, I've read that some people even though their car runs on either coil by itself still had luck changing the coils and having the lights go away. The coils were only $50 a piece.
I ordered two new coils, I've read that some people even though their car runs on either coil by itself still had luck changing the coils and having the lights go away. The coils were only $50 a piece.
02-26-2008, 07:18 PM
#18
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Well I just swapped the coils and it didn't help, would I have to reset the ECU? If it's a bad signal on the electrical why would it stay on and not just come in when the bad signal comes through, or am I way off?
02-27-2008, 02:28 AM
#19
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Too bad the coils didn't fix the problem. Shouldn't require a DME reset (mine didn't).
Have you checked the PDAS error messages using either the ScanTool software or a Bosch Hammer?
If you're ever up Edmonton way with the car I can hook it up to my laptop and pull the error codes for you if you don't have access to an interface.
Frank
Have you checked the PDAS error messages using either the ScanTool software or a Bosch Hammer?
If you're ever up Edmonton way with the car I can hook it up to my laptop and pull the error codes for you if you don't have access to an interface.
Frank
02-27-2008, 10:19 AM
#20
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Cody D
I had the exact same troubles, please see my posts " Damn Red Lights",
As i say, took out the two relays on the ABS, gave them a shake and put them back....All works fine... obviously it's not a satisfactory fix, as I have absolutly NO idea why lights came on in the first place , and even less why they have gone out now.
But..eh..give it a try and DONT forget to give them a SHAKE.
Ciao
Charlie
I had the exact same troubles, please see my posts " Damn Red Lights",
As i say, took out the two relays on the ABS, gave them a shake and put them back....All works fine... obviously it's not a satisfactory fix, as I have absolutly NO idea why lights came on in the first place , and even less why they have gone out now.
But..eh..give it a try and DONT forget to give them a SHAKE.
Ciao
Charlie
02-27-2008, 10:29 AM
#21
Rennlist Member
NEW COILS
BEFORE YOU BUY ANY MORE SEE MY POST. EVEN THOU YOU HAVE NEW COILS, IF YOU HAVE THE PROBLEM I DID YOU STILL WILL THE SAME PROBLEM. NOT TO SAY THIS IS THE FIX BUT IT COULD. IT SEEMS AS THOUGH IF THERE IS A IGNITION LEAK ON THESE CARS, ALL KINDS OF THINGS CAN GO WRONG.
02-27-2008, 11:11 AM
#22
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See my recent post "Magic Canadian Plug Wires" for an update on correcting my PDAS/ABS lights and alarms with new plug wires. I had solved the Christmas Trees with 2 new coils a couple of weeks ago.
I did not believe that an ignition leak would cause the alarms, especially the PDAS/ABS and was prepared to continue troubleshooting with cleaning the axial accelerometer. But 4 days now with no alarms, and they used to occur almost every trip, sometimes immediately after startup, sometimes after short distances.
I did not believe that an ignition leak would cause the alarms, especially the PDAS/ABS and was prepared to continue troubleshooting with cleaning the axial accelerometer. But 4 days now with no alarms, and they used to occur almost every trip, sometimes immediately after startup, sometimes after short distances.
02-27-2008, 04:26 PM
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I will look into your guys ideas, and Frankvan, it would be great if we could hook your laptop up to my car, I'm in Edmonton every once in a while, I'll just have to come up with some excuse next days off.
02-28-2008, 09:04 PM
#25
I had a similar issue with my ABS and brake warning lights on my '89 C4. I removed and cleaned my accelerameters and the problem went away. If you do this, take the caps off very gingerly. The part itself is rather robust, i was worried about cracking-off one of the tabs on the lid.
Good luck.
Good luck.
02-29-2008, 11:09 AM
#27
I do believe so. The accelerameters are the two little boxes mounted in the center counsel just in front of the gear shift. They could be seen in one of your first photos.
02-29-2008, 01:20 PM
#28
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05-22-2008, 02:42 PM
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Well just to update this:
I finally decided to just take it into a mechanic and apparently a relay was completely missing. I don't know why I didn't notice this, I thought I went through all of the relays.
I finally decided to just take it into a mechanic and apparently a relay was completely missing. I don't know why I didn't notice this, I thought I went through all of the relays.
