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abs inop/asr off grounded wire question

Old 01-01-2006, 11:10 PM
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abs inop/asr off grounded wire question

'96 with trac control. Had it scanned and was told passenger side was probably wheel speed sensor (something about it reading that car was accelerating). I'm gonna clean or replace it depending on price, anyone have a part number or know how much they cost?

Now, for the real problem. The drivers side has a grounded wire.. I thought, perhaps, it was my extensions that were causing the problem (routed around LTs) but they are not crossed and do have continuity. So, I checked the wires running to the plugs on the abs unit itself. Well, of the three plugs I believe I found a problem with the one on the far right (lowest and closest to the engine) the tan/white wire on that plug is grounded. I'm guessing this is my problem. I'd try cutting it and running a new wire but I just don't know where the thing goes. Does anyone know where it goes, or have any wiring diagrams for a 96 6spd with trac control? As far as I can tell from my chiltons manual it may run to a "brake combo valve" where that is I have no idea and the manual doesn't seem to mention it anywhere else. [rant] My stupid chiltons manual is worthless I don't think I've ever found a use for it.. maybe next time I run out of toilet paper...[/rant]

Here's a link to shoebox's site where you can see the wire I'm talking about. It's tan and white and it the upper right hand corner of the pic.. it's on the vertical plug.
http://shbox.com/1/abs_wiring.jpg

The abs inop light and corresponding asr off light come on pretty much immediately after starting the car. The car doesn't need to be moving for them to come on. While I imagine the abs does not work (haven't tried) I know the asr is in fact off. The car seems to brake fine and I have never experienced any braking problems (i.e. antilock engaging when it shouldn't).

I tried posting this in the computer tech but no one has responded so I thought this might be a better place. I'm sorry if the double posting offends anyone. Here's a link to that post:
http://web.camaross.com/forums/showt...28#post3545428

Thanks for any light you can shed on the subject. Help is much appreciated.
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Old 01-02-2006, 10:08 AM
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Re: abs inop/asr off grounded wire question

Everyone says "the brakes work like normal even though the light is on". They need to understand that an ABS failure will not interfere with normal braking or cause the brakes to come on when they shouldn't.

You also need to understand a few simple rudimentary things about ABS. The first is that there are hard failures and soft failures. A hard problem, failure or code, what ever your terminalogy, will set an ABS INOP when the car has not even started to move. A soft code will set the ABS INOP only after the vehicle starts to move. Wheel sensors only set soft codes. So if your light comes on even before your vehicle moves, it's not the wheel sensors.

It seems several folks think every time the ABS has a failure, it has to be wheel sensors. Those same people need to understand a hard and soft failure. Another thing to understand is how the wheel sensor operate. Because they are esentially a signal generator, if they fail, they can only have a lack of response as opposed to an extra response. That is they can only send too few of a signal, not too much therfore they can only act as if that wheel is turning too slow as opposed to turning too fast. Metal filings will not cause the wheel to appear too fast either. There are several other failures that sensors do have than just too little response. I'm not saying that is the only failure.

Now on to your tan/white wire suspected problem. That is one of 2 wires (obviously) that go to brake combo valve. The other wire (black/white) goes to ground. That wire and the tan/white wire goes to a switch inside the ABS motor pack. If there is an unequal brake pressure, that switch is closed causing the tan/white wire to go to ground IF IT IS CONNECTED. HOWEVER, if this switch is closed from an unequal pressure, the "brake" light would be ON at the dash. Therefore, if the "brake" light is not on, this switch should not be closed.

If you removed the plug from the ABS motor pack and ohmed the tan/white wire to ground, you still may have tested it incorrectly. The other end of the tan/white wire goes to the EB/TCM and it is solid state. It may have internal resistance to ground at that point. So if you are concerned the tan/white wire is grounded, you should unplug both ends and then check from that wire to ground. But you know if the "brake" light is not on at the dash, this wire is not grounded. Unless the gages fuse is blown. You know the fuse is good since the ABS INOP, TCS OFF work and are on the same fuse. So don't worry about the tan/white wire.

What I recommend is that you have it scanned for the exact code and post it here. Then I or others can help you go through the problem and eliminate those things that are NOT the problem so you can find the correct cause of the problem. I did it a few years back to discover the EBCM was bad. Knowing exactly what the problem was allowed me to find the EBCM in a junkyard for $25.00 instead of the $700.00 MSRP and I've been free from problems ever since. I must point out that I don't have TC and that system is far more complex therefore it is probably prone to far more problems.
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