I have a 87 vert and my abs light is always on. I cleaned up all 4 wheel sensors hoping that would do the trick but apparently it didnt. I was wondering where the abs module is located on the vert ? I know the coupes have them in the storage compartment area in the rear but where is it located on the vert ? Under the speakers in the rear ? Also the brake fuse was fine. How do I go about troubleshooting this ? Thanks.

 

:lurk:

 

Per Richard Newton "About the only time that something goes wrong is when a wheel sensor fails. That's the most common problem with the ABS sytems." He continues: "If this happens to you, I suggest that you let a professional diagnose your ABS problem." When the shop finds which sensor is bad you can replace it yourself. Let me step out to my garage a minute to get my 87 service manual and my C4 Chilton manual to find where the main sensor is located. :leaving:

 

Per GM Service manual 1987 Corvette: "On convertible models, access to the ABS components in the left rear storage compartment is accomplished by removing the left rear speaker." Hey I just learned something! Mine's a vert too and I did not know this! Thanks for asking. Also, you need one of these manuals. The chapter on the ABS system is full of "beware" and "caution" and "do not.....". You need to read this stuff before you get in there and freak something up! :eek:

 

Well I've got the Haynes manual and it didnt say much. Only had like a paragraph or two on the ABS system. And they keep referring to storage compartment in the rear. This is for coupes. They forgot about the Verts :rolleyes: As for the GM manual u stated.. it says storage compartment on the verts.. Since when did the verts have a storage compartment in the rear ? Am I missing something here ? :confused:


[Modified by 87vette, 12:39 AM 4/17/2004]

 

The storage compartments on our cars are under the speakers in back and not accessable like the newer cars..........great, huh?

 

I just found why my ABS also stayed lit the whole time. You need to remove the Right Rear speaker like previously posted. Mine is also a convertible like yours. Look in there and make sure all the ABS harness connectors are connected. Then disconnect the ABS Control Module relay and gently shake it next to your ear. It will have a 5 wire connector to it (Shown with the Red arrow below). There is only one relay in there, it's near the top and it has a metal clip on it. If you hear anything when you shake it, something came loose in it, and you will need to replace it. I opened my relay and found that the inside electronics of the relay were completely corroded and were nothing but chunks of rust. It fell apart in my hands. I would check that first.

Here is where the main ABS components are:
(Disregard that disconnected harness, that goes to the Bose System)

Some preliminary checks to do yourself

Trace the wiring of each wheel speed sensor back to the ABS Control Module that is located under the Right Rear Speaker. Check for open, damaged, and shorts to ground.

Check for dirty ABS harness connectors. Clean as necessary.

Check and make sure all ABS connector harnesses under the Speaker are connected firmly and securely seated.

Remove and gently shake the ABS Control Module Relay. If you hear something rattling inside, chances are it's corroded and the insides have deteriorated.

Check both the Guage and the Brake fuses.





[Modified by 86PACER, 2:34 AM 4/17/2004]

 

Thanks for the heads up. I will look into it this afternoon and let you all know what I found out. :cheers:

 

The Haynes manual is not really worth anything when it comes to servicing specific systems. You need to get the factory service manuals specific to your car year from Helms http://www.helminc.com The factory manual has the step-by-step info on diagnosis and repair of all of the systems on the car. You can also find factory manuals for sale oneBay from time to time

 

Well I took a look this afternoon and as you stated it was behind the right rear speaker. I took a look there first and there was only one wiring harness that is for the Bose speaker I assume. I have an aftermarket speaker there at the moment so that wiring harness is useless. So it got me thinking the 86 and 87 model years are different.
I then took a look behind the drivers seat and noticed a bunch of wires. At the bottom of the storage compartment under the speaker seems to be a brass/gold unit that says bosch on it. I looked around as you described but don't se any kind of wiring harness for the ABS. I did find one that I wasnt too sure about and it had a black box over it that was connected to the wall way under. Not sure what its for though. Is this what I'm looking for? It was attached the wall and I had a difficult time removing it. Didn't want to break anything.

 

The relay is about 2"x1" and has that 5 wire connector to it that is highlighted with the red arrow.

 

I can understand that.. however I see a black box with a metal clip on it that has a relay diagram on it as well. It has a 4 wire connector to it instead of 5. The colors are pink with black line, orange, black, and black with orange line. Are you sure its 5 and not 4 ? I see 2 other wiring harnesses that has 5 wire connectors. One of them has 2 green wires, two red, and a black. The other relay has 2 yellows, 1 black and 2 whites.

The pix in your picture is kinda hard to determine which one I'm looking at because the wires are taped up and hard to see in your pix. Would you happen to have another pix that is easier to see ?

Thanks


[Modified by 87vette, 8:37 PM 4/17/2004]


[Modified by 87vette, 9:15 PM 4/17/2004]

 

That is the one. It has the word "BOSCH" on it. It's a 4 wire not a 5 wire sorry, it will have 5 spade terminals when you remove it. That is where I messed up about the 5 wires. It has 4 wires and 5 spade terminals. The color of the wires are: Orange with black, Pink with Black, Orange, and Black. You found it. That's the one.



[Modified by 86PACER, 11:30 PM 4/17/2004]

 

With ABS lights, I usually look for a couple things.

First, a little about the system. When turning the key to the ON position, power flows through the power control relay heading for the ABS controller. When the ABS controller gets power, circuits turns OFF the light.(See 86 Pacer's post. You can also check this relay with a volt meter) When the car moves, rolling BIT/BITE (Built In Test, or Built In Test Equipment) check is initiated and pump cycles, sensors checked for signal, etc.

So, IF the light stays on, never goes off, I usually start with checking the relay and wiring to the module. As with any electrical issue, checking circuit ground is very important. If the light never goes out, this sends me to the power/module/ground route.

IF the light goes out, stays out till you start moving, this sends me to the sensors, and signal to the module. Bit check also cycles solenoids, pump motor, and checks sensor signal. Should anything fail bit, the light will again illuminate. The system continuously monitors wheel speed and should the signal deviate from the programmed amount, assuming no braking action, turns light on and disables ABS. With no codes, more difficult but not impossible.

Let us know.

dlmeyers 90 coupe zf6 3 speed shocks




[Modified by dlmeyers, 9:02 AM 4/18/2004]

 

Ok well here's what happens... When i turn the key the light does not come on. When I'm "coasting" such as rolling the light doesnt come on until I hit the gas and cruise at maybe 4mph. That is when the anti lock light stays on permanently. So that would tell me its leading to the sensors ? So I should take a voltage meter and check each wheel sensor then ? If that's the case where can I find some wheel sensors?

 

I've go the same problem on my '89. Started last summer. When I start the car, everything is fine - ABS Active light goes on and off like normal, no problem. Once I start moving, I can hear the pump working away for a second or so (accompanied by the ABS Active light) then it stops. But then, the ABS Active light comes back on again (sometimes more than once) for a few seconds as I continue to drive, and on occation I might hear the pump again. This is then followed by the ABS light coming on and staying on for the rest of the drive.

I have a feeling it's the wheel sensors. The GM service manual says that the sensors should have between 900 and 1500 ohms resistance.

But how do the sensors come off? I've never tried to remove them, and I'm in no mood to brake anything...

Hope you solve your problem. :cheers:

 

Where can I buy new sensors at a good price ?

 

They are held onto each knuckle by 2 screws. Be sure to clean off all the dirt build up on them before you remove them. Otherwise, dirt will fall into the hole in the knuckle and end up inside where the toothed wheel is. If you have never removed them, they might be a little stuck in there.

 

When I bought my 89 vert I had the same problem. Suggestion, take the car to a dealer and let them diagnose the problem. Won't cost that much and you will know exactly what is wrong. My computer was bad and I got a new one off ebay for $40 and the system has worked fine ever since. At the dealer they can unplug the abs computer, plus in their computer and run the system through its paces. I was told that the bosch pump unit is pretty much bulletproof and never fails. This was after a previous dealer told me the pump unit was bad. Let them do the diagnosis and then you do the repair... I think that is the cheapest and least fustrating option.

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