Help Please! Problem with ABS ECU on Range Rover

[ptjs1]

I wondered if anyone can help me with some advice on my 94 Classic 3.9 SE.

For a couple of weeks now, the ABS & ETC warning lights have been staying on all the time. The other brake light goes out as normal. The brakes feel fine but I haven't bothering jumping on the brakes or accelerator to see if the ABS & ETC circuits are working properly.

The car went in for its MOT this week and failed only on the fact that the ABS light won't go out. When they connected a code reader to the car, they said that they could see the other ECUs on the car but couldn't interrogate the ABS ECU. Their initial diagnosis is that the ABS ECU has failed in some way, causing the lights to stay on.

So any ideas where I should start? Most of the diag routines in the manual are based on being able to put a connector in between the ECU plug lead and the ECU itself, and then use a multimeter on various pins. I don't know where I could get one of those connectors at short notice. Are there any other tests that I can easily do to see if power and earth circuits are working on the ECU, for example? Are the ABS ECUs prone to failing, could I dismantle it and just spray it with contact cleaner to cure any dry joints?

Any ideas gratefully received. The MOT expired today, so I'm now off the road until I can fix this!

Tks

Paul

[ptjs1]

Today I decided to try the WABCO "blink" routine, just using a bit of wire to bridge the black & black/pink wires in the diagnostic plug under the passenger seat. (I looked at my dealer's so-called bespoke connector referred to in the service manual, and all it seemed to do was bridge these pins, so I tried it with a bit of wire). Sure enough, it worked and I found 7 fault codes stored in the ECU. I don't know why it had these codes which ranged from faulty left wheel sensor to stop light switch failure. Anyway, I cleared down all the codes using my little bit of wire and hey presto! the lights have now gone out! I just hope that they don't come back!

So, assuming it's still ok tomorrow, it's back to the garage to get my new MOT and ask for my £50 which they charged me for attempting the fault code diagnosis. I don't know what reader they were using, but my paperclip is much cheaper and apparently more effective.

[scoobyv8]

it seems paul, that your garage dosent want to spend too long checking the fault out (like my boss too) just because the ecu's not comunicating it dosent mean to say its fooked,

i use an expensive code reader at work, and ocasionaly it wont talk to some systems on a vehicle, the idea would be to have a look at wiring diagrams and use a m/meter or testlamp see why the systems not powering up. fixing the power fault might just put the warning lamp off, unless theres somthing else wrong

places to look -
check the abs fuses, and relays
and then
any earth points
and the conections at the pump, and abs ecu

and if your still failing,
use your meter or test light and start on the wiring

keep us updated
George

cough cough as an mot tester re wire the abs lamp with the charge lamp and the tester may never know. obviousley as a quick fix to get you through the test, you should still fix the fault for saftey reasons