Antilock Brake Problem

I have an '87 Turbocoupe and am getting service code #21. I've checked the resistance at the main valve and it looks okay. This indicates that the problem is in the wiring harness Circuit 430E or 493. Where do these wires run? Do they go back to the ABS computer in the trunk?

Thanks

If you're refering to the seven wire connector on the antilock valve body, yes, they go back to the antilock computer in the trunk.

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Joe F.

JR's Place - My 87 TC

I can't remember, but think, that the code 21 sometime is caused by the wires going into that valve/sensor at the front of the module being pulled too tight. That caused a code with me, and I pulled on the harness and plugged it in tight, and the light went off. It's that 2 wire connector right above the ground wire/screw that points at the radiator.

I'm refering to the two wires that plug into the front of the module...where do they go?
I've tried plugging the wires in again, cleaning contacts, etc, to no avail.

When you used an ohm meter, you seen 2 to 5.5 ohms at that sensor?

The grey wire is a ground, and the black/pink wire goes to the ABS module.

Yes, 4.5 ohms. I traced the black/pink wire to the ABS computer and it's okay. Where does the gray wire ground?

Have a test light? Hook the test light cable end to the positive battery post and then probe the grey wire. If the test light works, it should be OK.

By the way, the codes on the ABS don't clear unless the vehicle is driven above 25MPH, and the fault is no longer present. In case you didn't know.

Thanks guys, but I’m still getting error code #21 with my ABS system. I have checked the resistance at the two-wire connector at the main brake module, and it is within the correct range. I’ve cleaned the contacts at the two-wire connection. I’ve checked the continuity to the ABS module in the trunk, and it’s good. I’ve checked the ground wire, and it’s okay. What next?? Is it possible that this is a problem with the accumulator? Is the two-wire connector at the wir harness available as a replacement? I haven’t found one in the local salvage yard. Thanks!

Nothing in the hyd. system (pump, accumulator, etc) will trigger an ABS computer fault code.

The connector on the main hyd. valve (2 terminal valve sticking out the front of the MC) is the same as a fuel injector connector.

With that said, several years back, I had some serious weirdness with the ABS..... ABS light came on. Ran codes. Code 21 came up. Could find no fault with the main hyd valve or its circuit. Decided to manually check all resistances, voltages, etc at the 30 pin ABS connector. Found the LR wheel sensor had developed an open circuit. Replaced wheel sensor, and code 21 went away (after driving over 25 mph to reset it). This past winter, some furry creature chewed thru the LR wheel sensor cable, causing an open. Running codes this time gave the correct code for open LR wheel sensor. Go figure.....

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 21 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car)

[This message has been edited by Jeff K (edited 05-13-2005).]

Thanks Jeff,
Can you tell me how you checked everything at the 30 pin connector?
I checked resistances at each wheel sensor (nearest connector) a while back and didn't find anything wrong. Maybe the fault is somehwere in between.