ABS Woes - help needed... PLEASE"

[paulhavelock]

I'm having total grief with the ABS on my '98 V8. It has the later Kelsy Hayes 430 ABS. The issue is that the ABS light comes on an off off (mostly on) at random. This is combined with my speedometer not working, although the two issue do not necessarily happen together. I have tried new ABS sensors, checked and double checked the wiring but can't find the fault. I'm praying that it's not he ABS unit istself as it's

[lotusessex80]

forget the ABS! You really dont need do you? Pumping the brakes works for me. You can disable the ABS, I think there was a how-to-do in LEW

[superdavelotus]

The speedo is linked to the driver's side rear ABS sensor (I think). The toothed wheel on your hub could have magnetic filings on it or be dirting. Also the ABS sensor has to be within a certain distance to the toothed wheel. Lotus say it's between 0.6mm-1.4mm. Too close or too far and it'll throw up the ABs light. I suspect it's dirty. I haven't heard of the toothed wheel being dmagaed or loosing a tooth.

Do you have the service manual? If not I can email you this section. Just pm me with your email address

[Gav]

I had problems with my ABS light not always going off when the ign is turned on. Trouble was the computer did not put up any fault codes. I suspected it to be a power problem but couldn't find it. It has now gone away since I changed the battery - which finally let me down and wouldn't start the car even after a 30 mile drive.

Not sure if that helps you, but try checking if there is a dodgy power connector or earth.

[DJ504]

I am experiencing the self same ABS light problems as Paul H. Fault code shows right rear sensor problem. This has been replaced however the light comes on totally randomly. I've also had the occasional speedo needle bounce.

Driving in reverse then forward without braking makes the light go off 9 times out of 10!

Paul, if you managed to sort out your problem then please let me know. If anyone has more advice they can offer it would be very welcome - just got a price of

[BC007]

I had problems with my ABS light too. It was either flashing or stayed on. I tried pumping the brake pedal but nothing seemed to work. Then it progressed to intermittant brake failure! I would be driving, touched the brake and although pressure was still there, the efficiency dropped to almost 10% but really felt like nothing at all! This is really frightening and it was only because I left plenty of space in front that I didn't have a nasty accident. After much investigation it transpired I needed a new accumulator which unfortunately is expensive. All good now.

I would respectfully advise anyone with similar problems to get to the root of the problem quickly. Don't mess around. It really is scary not to mention dangerous when you touch the pedal and nothing happens - believe me! The ABS light could be flashing for good reason!

Edited November 2, 2006 by BC007

[Jonathan]

Sounds as if you might have poop on the pole wheel.

If you replace the sensors correctly with the correct set distance you might want to get your head in next to the gearbox with a torch and look back into the centre of the hub carrier which is where you'll find the pole wheel pulse generator for the sensors.

When I've worked on my cars I've noticed rubbish on them including brake dust and so on on the magnetic pic ups of the sensor and this will dog the reading.

Might also want to make sure the wires coming in (should be 3 per sensor - 2 signal and 1 grounded sheath) - you need to ensure the grounds are present and not broken etc - you could be getting noise in on the signals.

Failing that I would get it looked at propperly, anyone with an oscilliscope can do it by putting the probes on the sensors, jacking the car up and spinning the wheels and observing the wave form at source and at the ends of the wires.

Personally I would get the problem fixed as opposed to leaving the ABS off.

ABS is a very important safety feature of the car esp in the winter weather - unless you're used to driving without it then leave it on.

[paulhavelock]

Gents,

Thanks for all the advice - I have fixed my ABS now. The issue was the ECU on the top of the ABS unit, it had a cold solder / intermittent connection. I had the unit repaired by Autotek in Poole, Dorset. The ABS ECU just unscrews - 4 torx bolts (mine is that post '98 Kelsey Heyes 430 type, not the pre '98 415 type), you do not have to break into the hydraculic circuits at all. Sent it away, they repaired it, took