SERVICE ABS + Problem

[c4koh]

About a week ago, the "SERVICE ABS" light came on, my ABS is now not working (or disabled) and I'm stumped.

This is on a '91 ZR1.

I've gone through everything in the service manual: the 3 fuses (BRAKE, STOP & AIRBAG) all OK, "Flash Code" diagnostics don't help at all... I have come to the following conclusion:

- the EBCM (electronic brake control module) may be knackered (replacement is $624)

... or ...

- the EBCM is fine, but the problem is one of 5 codes which *aren't* viewable using flash code diagnostics, rather they need a Tech 1 with the ABS connector...

--------

So, long story short, I need this Tech 1 tested, to see if it's a problem with the EBCM or one of its sensors... I suppose BM in Manchester?? What sort of rates do they charge? Anybody / Anywhere else "up North"??

Anyway, since I don't have the luxury now of ABS, I can pretend I'm in a TVR

Thanks in advance.

[te51cle]

Does the manual cover checking the wheel sensor connectors and wiring ? Just wondering if at this time of year it could be a bit of salt water intrusion/corrosion ?

[c4koh]

I haven't checked any of the sensors (although that was one of my first thoughts of things to check)...

Reason I *haven't* checked is that the "Service ABS" light should flash in diagnostic mode for a wheel-sensor problem, and it doesn't... (hence not indicating that being the issue)...

[Gixer]

I've had some experience with the ABS system on my 90Z.
Firstly, are you sure you can't get any codes to flash up on the DIC by shorting the pins???? How about clearing the codes??

I have my old EBCM still, its a shame you are not nearer as you could try it to see if yours is at fault or not. My old EBCM is faulty, it will set 2 codes, one for a front wheel sensor and one for the opposite rear but that is all it will do. It still runs the self test at pull away. BTW is your EBCM still running the self test at pull away???

As for the Tech1 and brake cartridge, you really could do with the pin out box as well. The only person I know that has all that and the know-how to use it is Paul Gamsa. He couldnt live much further than you (New Forest) but is usually on the ZR1 Net mail server although he has not posted much recently.

Out of interest, and this was something I was going to try before I had help from Paul. The old Audi Quattro coupe turbo from around the 86 and on period appear to have a similar ABS set up using the same Bosch EBCM, connections. Even the long part number is the same down to the last four digits. I know this as a friend has an 86 turbo. I would expect the calibration set up to be way off comparred to our set up but if you could get your hands on one it may help trouble shoot/eliminate your EBCM.

Sensor faults caused by crap getting between the sensor head and the time ring are common. As it is easy to remove and check/clean all four sensors with the wheels still on I would do that first. May be worth pulling a sensor from the harness and driving the car. A code should be set and that should be readable on the DIC. If that isn't showing either then that would point to a further problem.

[c4koh]

Gixer said:

Firstly, are you sure you can't get any codes to flash up on the DIC by shorting the pins???? How about clearing the codes??

Absolutely, shorted pins A-H and no codes; the service manual says that if I don't get the "12" code, then the problem could be one of 5 others which *don't* work using this "flash-code" diagnostic mode.

Gixer said:

I have my old EBCM still, its a shame you are not nearer as you could try it to see if yours is at fault or not. My old EBCM is faulty, it will set 2 codes, one for a front wheel sensor and one for the opposite rear but that is all it will do. It still runs the self test at pull away. BTW is your EBCM still running the self test at pull away???

I don't know if it's doing the self test; I don't think so - the "service abs" light is on straight from the start...

Gixer said:

As for the Tech1 and brake cartridge, you really could do with the pin out box as well.

... I followed the instructions in the service manual, and I got by fine without the pin out box!! just use the terminals from the EBCM connector, it works fine!!

Gixer said:

The only person I know that has all that and the know-how to use it is Paul Gamsa. He couldnt live much further than you (New Forest)

... yes, 5 hours drive

Gixer said:

Sensor faults caused by crap getting between the sensor head and the time ring are common. As it is easy to remove and check/clean all four sensors with the wheels still on I would do that first. May be worth pulling a sensor from the harness and driving the car.

I tried that, going along the same lines as you; this *should* give another code, but the manual - sigh! - again states that regardless of the codes, *if* there are the 5 codes 41-63, then flash-code diagnostics are disabled so really I do need a Tech 1... The problem should be either one (or more) of those 5, *OR* a bust EBCM...

Anyway, I'm going to look through the diagnostics for the faults 41-63 and see if I can prove *if* there's a problem there...

Anyway, thanks for the help - and a Happy New Year to you!