Hi all,
In short, my ABS hasn't worked in years (indicator on, so presumably disabled), but I got my exhaust pipe repaired a month ago and now my ABS stays enabled and engages at improper times (presumably because it really is broken). Does anyone know how to explain this? I couldn't find this problem in an existing thread.

Here's the long story: In 2004, my indicator light came on in NY while I was there for the summer. A brake shop said they couldn't read ABS problems from a '94, so I had to take it to the dealer, and they charged me $550 to replace a sensor. The next year I was back in Urbana, IL and the light came on again. As a poor student, I decided ABS wasn't worth $500 every year to replace the next broken sensor, so the light stayed on and the ABS disabled itself ever after. Now I'm in CA, and a month ago I took my car in to replace a section of exhaust pipe that was rusted from the salt back in IL. Problem solved there, but now my ABS has mysteriously started engaging after its long dormant period. At first, the indicator light would come on, but it would take 10 minutes instead of 10 seconds as it used to do. Now, the light never comes back on, so braking is randomly jerky whenever the system decides to act. I don't know how to explain this behavior.

Thanks in advance for any explanations/suggestions!

 

I would short the service connector just like you would to get the check engine light, but count the ABS light flashes. Read the thread called How to Check CEL codes in the DIY section.

The ABS codes are two part codes, unlike the check engine light. There will be a main code, then a sub code, so you would get a 1-2. You can also download a 94 shop manual from one of the links in the online manuals thread in the DIY section. The abs section will describe how the codes blink.

Post any codes you find on here.

 

Thank you, PAhonda.

I followed the instructions on this website that your thread referenced:
CEL Check Engine Light

The plugs were not connected to the blue housing. Does that matter, or does it just hold them in place? Anyway, I shorted the two-wire plug and turned the key to II.

Here is the blinking I saw: 3,1 long pause 4,1 long pause 3,1

I found a manual in one of the links in the Online Manuals thread, and this seems to indicate a problem with the right-front pulser and right-front wheel sensor, though it lists many probable causes (including faulty control unit).

I'm still confused why the indicator light doesn't turn on while driving now. A problem with a sensor seems like a problem that doesn't solve itself. The sensor code has a diagnostic tree I can follow further, but I'll need a meter to check resistances before I can report those results.

Thanks again for your help.

 

Both those codes are for the front passenger side sensor. They are held in by two bolts. You may want to clean any debris/grease off of the sensor. Also check and clean the toothed strap around the CV joint as well. Clean the electrical connector and inspect the pins to make sure you are getting good contact.

If you find that you need to replace, then get one from a junkyard. Those senors typically last for a very long time.

Good luck.

 

Thanks, PAhonda. I'll review the manual and see if I can locate those parts and check things out myself.

Why do you think the ABS system is "passing" the self-test? I'm not surprised there is a problem with the sensor, but I cannot figure out why the system no longer detects a problem and allows itself to engage.

 

System is capable of detecting an open or short, which you probably don't have. System is also capable of detected weak or missing pulses, which you do have, but likely intermittent or the system checks several start cycles for same behavior before setting ABS light on.

Clean sensor and tone ring wheel good and I think you'll fix the problem. Tone ring is cleaned by stuffing a rag down the sensor opening and turning the wheel by hand.

good luck

 

sorry, newbie question: will I be able to access the sensor (for cleaning) and the connector (for continuity check) without removing the tire? Or, do I need to jack up the car and take the tire off to access the sensor? It's difficult to tell from the manual diagrams.

Thanks!

 

You have to remove tire to access. Get a manual from Online Manuals post in DIY forum.

good luck

 

I attempted to clean the sensor this weekend but ran into a couple problems. First, I realized a 12 mm wrench is the true tool for unbolting the sensor. My 1/2" is not close enough, particularly since the bolts are in an awkward location and the bolts were very RUSTY, so I don't know how easy it will be to get the sensor back on even if I can get it off. I tried to clean as much around the area and in the gap as possible. Also, I located the sensor connector under the hood and cleaned the exterior. Unfortunately, the right connector is under a bunch of other connectors in an inaccessible crevice, and I couldn't get it open to check for cleanliness. That was frustrating because the left-front sensor is in a really convenient location and is easy to open and check.

I measured the resistance across the sensor from the ABS control unit connector, and it is ~5 kohm now, so it seems lower than before, but still not correct. Upon test driving, I found that the ABS still unnecessarily engages, but maybe less than previously. Perhaps a cleaning by a professional could really get this working correctly.

 

Are you sure the ABS unit is causing this issue. I've re-read your first post, it "appears" that the light is not coming on.

Turn the key to on - bulb check should cause the ABS, CEL, SRS (?) to come on...does the ABS bulb work.

Could be way off here, not the first time. I'm going with the bulb has finally burned out and you are chasing a regular brake issue, rather than the ABS has all of the sudden fixed its self and now giving issues........