Forgot about my MOT which expires on Saturday, so I'm booked in Saturday morning. And now the orange ABS light is on all the time. I know my limitations, and NEED this fixed for Saturday!

Previously, I would turn on the ignition, the pump would prime, and the light would go out. Then, when I reached 30-40mph the light would come back on and stay on till the car was parked.

I don't think the ABS ever functioned but I never pushed the car hard enough to find out.

Recently, I had the dash out for welding so disconnected the ECU and ABS ECU and when I've put it all together the orange light comes on with the ignition and stays on, but the pump fires up as required.

The red light goes out when the handbrake is released.

While I was working in the garage with the car in pieces I noticed that occasionally the ABS pump would come on even with no key in the ignition.

Any help gratefully received....

 

What car is it? There are ABS fuses and relays in the passenger footwell (right hand side). I've got the wiring diagrams if you can tell me what motor it is.

 

It's effectively a November 1991 2.9 XR4x4 - all the electrics and mechanicals were moved into a new XR4i shell.

The wiring diagram might be helpful to the sparky if I can find one in time, but I know my limits and electrics are just a mystery.

 

On the sensor thing, is there a method to get them out of the front hubs in one piece?

 

Patience really, try using WD40 etc and gentle wiggling from side to side etc up and down.

They can sieze into the hubs and have been known to snap, I have the same problem with one of mine (Offside front). Trouble is you can end up breaking them, when refitting use some Lithium based grease on the sensor body to prevent this issue in the future.

Martin

 

As above, basically I'd buy a new/spare set if they have never been out under your ownership, 99% probable they will be stuck and break.

 

Well, the new problem of the light being on all the time has sorted itself - I found instructions on sensor tests from Jon@work in another thread and unplugged the ABS ECU, checked the ohms across the terminals (which were all correct) and plugged it back in - bingo - light clears itself. Off for a spin now to see if it comes on at speed.

Also noticed that the oild pressure light has stopped coming on. Could be the bulb but is that an MOT item now? If it is, I have the one beside the oil pressure gauge.

 

Must have been a bad connection in the plug then, no thats not a MOT item.

It's most likely a faulty sender unit.

Martin

 

I spoke too soon. The light stayed off till 40+ mph then came on and stayed on. Stopped the car for a while and on restarting the light was on from the outset. Switched off and back on - still the same.

Seems I have a loose wire or connection somewhere in that area, but the oil light is working again! And now the rain is on again.

Thought I had some spare ABS sensors on the shelf, but no idea which is which or if they are any good. Beginning to wish I'd just stuck a good old-fashioned servo on this thing!

 

With you disconnecting the module, you must have re-set it.

Sounds like you could have a sensor issue.

If you have some sensors check the resistance of them.

Also, if oil light has been playing up you could have a dash wiring issue?

 

More info.

I went thru all the stages in Jon@work's MAIN ELECTRIC VALVE TESTS and CONTROL ELECTRO VALVE TESTS and got readings within parameters for nearly everything. The exceptions were:
Connect ohmmeter between ECU connector terminals 11 and 18 - should be 2-5ohms, I got 1.2
Connect ohmmeter between ECU connector terminals 1 and 11 - should be less than 1ohm, I got 1.5

Also started on the WHEEL SENSOR TESTS but I was on my own so could only really check resistance. At the ECU connector and they all came in between 1048 (LH Front) and 1065 (RH Front). The two rears were both 1060.

I put a spare ABS ECU in and the light went away and the oil pressure light came on, but as soon as the car hit 45-ish the light came on and stayed on after the car had been switched off.

I pulled it out again, reconnected and drove the same route at 40mph so keeping the light off. Came home, parked up and restarted - no light.

Refitted the original ABS ECU, went back out and as soon as I hit 45 the light comes back and stays till I disconnect again!

So, for the MOT I just won't drive fast on my way there, but any more ideas?

 

Sounds like you have the same fault as my cossie.Bloody abs.Its getting on my tits.

 

It sounds like a faulty sensor or corroded rings. I had a customers car do exactly the same - start up - self check all fine light goes out drive it over 30ish and the light would come back on.

I changed the drivers sensor becuase it snapped when i removed it and cleaned the sensor hole on the hub because the sensor gap was too big. Be careful when you bolt the sensors back in make sure they are properly seated before starting to put the bolt in don't expect the bolt to pull the sensor down because it will deform and look like its seated but it's not.

 

I agree that a sensor or ring is causing the light to come on when the car gets up to speed, but I've been pointed towards a sticky relay being the reason the pump sometimes runs even when the car is switched off. That would also explain battery drain, and why the light won't go away after it has illuminated.

Question now is, which relay in the passenger footwell do I need to be looking at?

 

Would corroded rings cause the light to come on?

I will have to have another look at mine cause its getting on my tits now.

 

I'm sure it's the purple one
Pull out the sensor and clean it and especially the teeth in the hole, rotate the wheel and clean them all and get all the crap and grease out, sure that'll do the trick, use a small flat headed screwdriver and some WD40 or the like to get all the shit out.

 

How often does it fire the pump in 1hr? Because I'm nearly sure my old car used to do the same.

Have you checked the current draw with the engine off? Alarms will kill batterys another thing do you have another car near it with central locking it could be waking your alarm up when you open and close it.

 

Swapped out the green relay with a spare and now the light only comes on at 40+ mph and goes out when I switch off the ignition, only coming back on at 40+ again.

I've spent the afternoon in the garage and the pump didn't fire once, until I started up to move the car, so I'm kind of back where I was before I dismantled the car.

Don't think it was alarm related because it did it with my home-installed system, and continued when that had been removed and replaced by a pro installation. If another remote was interfering, would that not sound the arm/disarm bleeps? If so, I'm not getting any of those.

Didn't have time to do the sensors but will the MOT do a road test at 40+ (the car is 4x4)? Working alone, how easy is it to identify which sensor is giving me trouble?

 

Your not running different profile tyres on each axle are you, or brand new on the front and nearly slicks on the back lol, the rolling radius difference could be throwing up a fault.

 

Nope, 4x brand new and identical Continentals with less than 1100 miles on them.

The bloke that pointed me to the relay says it could be a resonance in a sensor that has dried out.

 

It's definately a sensor issue if it only comes on at speed and resets after switching off.