ABS LIGHT

[man of kent]

Read all the history on the ABS light but as the ABS has done some 'things' it might isolate the problem for me.

Firstly, been spraying silicone around and some got on a rear sensor.

Light comes on and goes out when you start. Comes on again about 5 seconds after moving off and stays on. Same sequency next time you start.

Today at low speed when braking, the ABS clattered on through the brake pedal twice and the light went off. A little while later it came on again whilst driving.

Doesn't sound like a relay to me?

Suggestions?

[man of kent]

Tried cleaning off the silicone spray in case this was interferring. No luck.

Light still comes on after about 5-10 seconds after driving off. On a couple of occasions the ABS has come in (felt through pedal) whilst braking at slow speed and the ABS light goes off. But, further up the road it comes on again.

Suggestions?

[Murph]

Sounds like a sensor problem.
Usually it's a rear sensor... we have spares too!

I'll have one to hand on sunday and should have that door here too.

[24vman]

Are you sure your alternator is pushing the correct voltage.

The ABS really plays games if not.

[man of kent]

Are you sure your alternator is pushing the correct voltage.

The ABS really plays games if not.

Interesting. Didn't know that. Starts first turn of key, so should be ok. The alternator as far as the history goes is the original, so maybe - 115k miles! Seeing Murph soon and he said he will swop over the relays to see if its them.

[man of kent]

The latest is weird.

Drive off from cold and reduced braking, possibly one circuit only with no ABS light.

Shortly after the ABS light comes on with full braking restored!

This is the opposite to what it should be. Murph and I are going to take a look thursday. Any suggestions would be helpful.

[24vman]

Check the voltage over the battery.

I had this on my 24v.

[man of kent]

Check the voltage over the battery.

I had this on my 24v.

Car left for 2 days. Static across battery 12.25v.
Started and on choke (fast idle) 13.9v
Turned engine off after 2 minutes, across battery 12.7v

Cannot see anything wrong with that.............13.9 volts when I pull away with poor braking until light comes on and then full braking. ABS has been clicking in at slow speed braking a few times, light goes out immediately and then comes on again after about 5-10 seconds.

[Whippit]

Only time I had anything like that it was cracked sensor ring.

Its got to be that or a duff sensor

[man of kent]

Murph changed the 3 ABS relays with no improvement. Next step is to check the front sensors and rings for crud. Cleaned the rears already.

Must find the ABS sensor thread to test them individually.

[Murph]

It was worth a try.
Thanks for dropping my phone etc off with Chris for me Kieth.

I left it in the car after changing the rear door... DOH!

[man of kent]

Amazing. The light has gone off and stayed off!. Two possible reasons, muck in the front hub/sensor or, and I think this is the reason, the silicone spray I accidentally sprayed on the a rear sensor has dried out. Maybe the silicone spray interfers with the pulse to the sensor?

Dont spray silicone on the sensors, just in case.

Sorry i could not get the phone back quicker. We were baby sitting and running the grandchilred around and Gill needed the car.

[Murph]

No problem at all Kieth, I was just grateful that I didnt have to drive to Maidstone to get it.

[man of kent]

Sods law. After a week of no ABS light, it came on again but without the associated ABS pulse thru the pedal. An investigation of the front sensors and ring will have to wait. The relays are ok.

The brakes work just fine with no problems! Just the light.

[man of kent]

Look the front discs off today and cleaned the ring & sensors but no luck the light is still on after about 5 seconds driving. Thats the front & rears cleaned.

So, its probably a sensor but which one?. Murph suggests its usually the rears. Could change both if they are available. Murph also said that somewhere on TC is an article on testing the sensors but I cannot find it. Is the author around who can identify it for me.

One item that worries me. The car has had a brake fluid change every year. Thats about 20 fluid changes which means 20 chances of garages getting air in the system and especially the modulator. Reading some web articles you can get air in the modulator and need special equipment to get it out. Bleeding normally doesn't get it out. It does however say that its accompanied by a spongy brake which I haven't got.

The only other clue is as mentioned above, occasionally the pedal vibrates as if the ABS is working BUT the light goes out for a while & then it comes on again.

Are the front and rear sensors the same? Could buy a pair and try them on the front and rear if they fit.

[Murph]

They are the same I think, but the real problem lies in getting the front ones out of the hub assembly.
I have only ever heard of one instance of someone getting one out intact.

[Murph]

Simple test outlined here

[carlton_mad]

think they are different dude the wire seems much longer on this one!!

http://www.vauxhall-car-parts.co.uk/acatalog/VAUXHALL_FRONT_ABS_SENSOR_-_90510208N.html

[Murph]

Aha fair point!
So the sensor is pretty much the same but the wire length is different.
I'd say you could use any one for testing purposes but not permanent fitting.

[man of kent]

Simple test outlined here

Thanks Murph. I'll do this check.

The problem really started when I sprayed silicone on the rear sensors. Yet cleaning them has made no difference. I'll try some carb or brake cleaner. Perhaps the spacing is incorrect. I think there are spacers to adjust the position of the sensor.

As a matter of interest the fronts just had a lot of brake dust and there is a very small gap at the backplate you can put an air line to. You dont need to take the disc off to clear the dust. I wanted to know what was in there!

[melinx]

Maybe the link below will be some help ?

As stated in the link, the sensors only detect Iron or magnetic material; the toothed ring could be full of mud or the teeth filled with araldite, it would not affect the operation at all !

http://www.topbuzz.co.uk/maintenance/testing_abs/testing_abs.htm

[24vman]

I hate the ABS system when it goes wrong.

I can never sort it out regardless of what I do to fix or test it.

[man of kent]

Did the resistance test on all 4 sensors and wires. All ok. The resistance reading changes each time I spin the discs. Should have of course checked for the correct voltage as well but its difficult getting the voltmeter wires inside the connected connector. Blast. Now have to check each one for voltage.

Before I do this are there any connectors to check. There are some under the plastic cowl panel but dont want to disturb them unless I have to. Murph changed the relays and I've just checked the wiring plug. All seems ok inside the relay cover.

I've had ABS on various cars and the buzz from the pedal is quite different. Its extremely fast and is more of a buzz than the usual rythmic pulse.

Cannot understand how the ABS works when I lock up, but the light comes on.

[man of kent]

I've done all the wiring voltage tests and no solution. Reading the manual and also on the VX site it states there is a surge relay in the black cover behind the nearside front suspension tower. Its the 'tall one' the website says. I've only got one relay in this box and this I'm sure is the fuel pump relay. So, did Vauxhall delete this relay on later cars or relocate it? I changed the ABS relay on the modulator with one Murph had from his car, but this did not solve it.

My car is a 1993 2.0. Can somebody check and see what relays they have in this black cover. Have I got one missing?

Although I cannot recommend it, apparently you can solder a wire from the back of the ABS bulb in the instrument panel to the engine management bulb or glow plug bulb if you have a diesel. The light then goes out on start up. As the brakes operate in 99% of cases except on ice it does help to get it through the MOT. I would not feel too guilty about doing this as most cars I have owned did not even have ABS and you should not be going fast enough to need ABS. Its been proven that cars with various safety items added are driven faster because the driver feels safer!

I would prefer to find the fault................As its intermittent I'm suspecting a relay somewhere.

Alternatively, does anybody close to me in Chatham have a diagnostic unit to identify the fault. Dont think my small local Vauxhall dealer still has his and I'm sure it would be a £100 just to connect it.

Got 4 weeks to solve it before the MOT and I need to put it in store whilst I'm in hospital for a while.

[Whippit]

thats the abs relay, the fp relay moved to the drivers kick panel in 1990