ABS mystery!

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Biastai

Biastai

Active Member
Posts
126
Location
North East England
I am really stumped. I have my ABS and traction lights on permanently after I had a faulty bearing knackered the ABS sensor and ring. Ring and sensor all replaced. On a 4.6 2002 by the way.

The lights have not gone away! I have replaced some other easy bits, brake foot pedal switch and accumulator. I have also tried another ABS ECU. All to no avail!

Diagnostics show all wheel sensors as working and the only fault that comes up in ABS is "Engine speed input signal intermittent or missing" Does anyone know what this might relate to? Could it be the camshaft sensor, as this has a dodgy cable? This fault will not clear as when I clear it and search again it is still there.

Appreciate any insight!

B
 
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Biastai said:
I am really stumped. I have my ABS and traction lights on permanently after I had a faulty bearing knackered the ABS sensor and ring. Ring and sensor all replaced. On a 4.6 2002 by the way.

The lights have not gone away! I have replaced some other easy bits, brake foot pedal switch and accumulator. I have also tried another ABS ECU. All to no avail!

Diagnostics show all wheel sensors as working and the only fault that comes up in ABS is "Engine speed input signal intermittent or missing" Does anyone know what this might relate to? Could it be the camshaft sensor, as this has a dodgy cable? This fault will not clear as when I clear it and search again it is still there.

Appreciate any insight!

B
Click to expand...

After a quick look, as far as i can see, there should be an engine speed signal from pin 34 ECM module to pin 4 ABS ECU. This would i think come from CPS. If the cam sensor cable was duff the engine would be all over the place.
 
Hmmmm! Engine is as smooth as a babies! So am I right in surmising that it is probably getting to the ECM? Therefore could it be that the signal is not getting to the ABS ECU and so throwing up the fault? Can I check this with a multimeter?

I know there is an alternating 0-12v signal that is present on live data! I think this was relating to engine speed......
 
Last edited:
Biastai said:
Hmmmm! Engine is as smooth as a babies! So am I right in surmising that it is probably getting to the ECM? Therefore could it be that the signal is not getting to the ABS ECU and so throwing up the fault? Can I check this with a multimeter?

I know there is an alternating 0-12v signal that is present on live data! I think this was relating to engine speed......
Click to expand...

The ABS ECU obviously doesn't think there is. :D
 
Biastai said:
oops! ECU pin 32 is crankshaft not camshaft! I have changes the crankshaft sensor too!

So is it the crankshaft wiring I should be looking at?
Click to expand...

The gearbox, EAS, Rev counter, ECM Etc also use engine speed signals if they are getting theirs and the ABS ECU is not getting it's, then maybe the ABS ECU is the place to look or at least the connection to it.
 
Cheers Wammers! I think I will have to start finding where all the wiring goes, back from the ABS pin then, as I have tried another ECU and issue remained.

Arse! Pin 4 you say! Right that's tomorrow afternoons job.......
 
Apologies for 'hi-jacking' this thread... but I have a similar issue... Firstly I'm 'happy' to announce that I recently bought back my 2000 p38 4.0 HSE Thor back of lad who bought it from me in Oct 2013. My P38 has just turned 90000 miles and still a pleasure and faultless drive after enduring a 'powerless' Shogun Sport TD for the last year. When I say pleasure, I mean until today!... when in slow moving traffic the dreaded ABS Fault Traction fault message appeared with the associated warning lights/buzzer. Then I recalled that intermittently last week I was getting rear LH bulb failure warning message... but when i checked bulb it was working...then next time it was not working !... I have replaced all rear light bulbs today -all lights are now working. I also replaced the BRAKE LIGHT SWITCH having read posts on this forum.... But the ABS/TRACTION warning message and lights are still on. !!
Is there a particular method for fitting a new Brake light Switch and Does the battery have to be disconnected before disconnecting faulty switch ?
I do not have a Nanocom or similar....will the fault messages/warning lights remain 'on' until 'cleared' by Landy dealer's computer?
Is the switch for Cruise control -cut-out ( above the brake light switch ) connected in anyway into ABS circuit ? Reason I ask is that my son tried to remove it thinking it was the brake light switch and broke it's fixing lug in the process :rolleyes:
I have ordered a new Criuise control switch - the broken switch is no longer attached to the pedal mount bracket -thus the pushrod is fully extended gut it is still plugged into wiring loom and vaccumn hose still attached.
Any tips ?
ps: It's great having the V8 Rumble /power again... I can once again overtake other vehicles ;)
 
V8HSE said:
Apologies for 'hi-jacking' this thread... but I have a similar issue... Firstly I'm 'happy' to announce that I recently bought back my 2000 p38 4.0 HSE Thor back of lad who bought it from me in Oct 2013. My P38 has just turned 90000 miles and still a pleasure and faultless drive after enduring a 'powerless' Shogun Sport TD for the last year. When I say pleasure, I mean until today!... when in slow moving traffic the dreaded ABS Fault Traction fault message appeared with the associated warning lights/buzzer. Then I recalled that intermittently last week I was getting rear LH bulb failure warning message... but when i checked bulb it was working...then next time it was not working !... I have replaced all rear light bulbs today -all lights are now working. I also replaced the BRAKE LIGHT SWITCH having read posts on this forum.... But the ABS/TRACTION warning message and lights are still on. !!
Is there a particular method for fitting a new Brake light Switch and Does the battery have to be disconnected before disconnecting faulty switch ?
I do not have a Nanocom or similar....will the fault messages/warning lights remain 'on' until 'cleared' by Landy dealer's computer?
Is the switch for Cruise control -cut-out ( above the brake light switch ) connected in anyway into ABS circuit ? Reason I ask is that my son tried to remove it thinking it was the brake light switch and broke it's fixing lug in the process :rolleyes:
I have ordered a new Criuise control switch - the broken switch is no longer attached to the pedal mount bracket -thus the pushrod is fully extended gut it is still plugged into wiring loom and vaccumn hose still attached.
Any tips ?
ps: It's great having the V8 Rumble /power again... I can once again overtake other vehicles ;)
Click to expand...

Did you fit the brake switch correctly. Fully extended then let the brake pedal back to set it? Cruise switch should have no effect on ABS but you will not be able to engage cruise with switch open circuit.
 
wammers said:
Did you fit the brake switch correctly. Fully extended then let the brake pedal back to set it? Cruise switch should have no effect on ABS but you will not be able to engage cruise with switch open circuit.
Click to expand...

Hello again Wammers and thanks for the prompt reply... I never disconnected battery nor turned on the igition during fitment of switch and I never compressed the new switch piston/plunger rod... but my son may have !.. I pushed brake pedal down...inserted new switch into mount bracket and turned it in the bracket to lock it in position then released brake pedal ... was that the correct procedure ?

Would I be right in saying the plunger rod should be fully extended when fitted ? just wondering what if my son had pushed it back and it 'set' prior handing it to me to fit into mounting bracket ? ..Having said that... I have checked operation of new switch and the brake lights are working ok.

So do I now need to get P38 plugged into LR computer to clear fault msgs / warning lights ... or should fitting the new switch have sorted the warning lights ( assuming fault was the switch in first place) ?
 
V8HSE said:
Hello again Wammers and thanks for the prompt reply... I never disconnected battery nor turned on the igition during fitment of switch and I never compressed the new switch piston/plunger rod... but my son may have !.. I pushed brake pedal down...inserted new switch into mount bracket and turned it in the bracket to lock it in position then released brake pedal ... was that the correct procedure ?

Would I be right in saying the plunger rod should be fully extended when fitted ? just wondering what if my son had pushed it back and it 'set' prior handing it to me to fit into mounting bracket ? ..Having said that... I have checked operation of new switch and the brake lights are working ok.

So do I now need to get P38 plugged into LR computer to clear fault msgs / warning lights ... or should fitting the new switch have sorted the warning lights ( assuming fault was the switch in first place) ?
Click to expand...

Switch should be fully extended when fitted with brake pedal depressed. Releasing brake pedal pushes plunger into switch to set it in correct position.There are two sets of contacts in it. If you use diag you will see that when the brake is applied one set of contacts is made and one set broken. This must happen or the ABS lamp will illuminate along with ABS fault message.
 
wammers said:
Switch should be fully extended when fitted with brake pedal depressed. Releasing brake pedal pushes plunger into switch to set it in correct position.There are two sets of contacts in it. If you use diag you will see that when the brake is applied one set of contacts is made and one set broken. This must happen or the ABS lamp will illuminate along with ABS fault message.
Click to expand...

Thanks for clarifying that Wammers... similar then to VW Golf/Audi brake light switch replacement but what do you mean 'if you use diag you will see' ? Also if switch is not 'set' correctly...can it be returned to factory 'new' position ?... once i have removed it off-course
 
V8HSE said:
Thanks for clarifying that Wammers... similar then to VW Golf/Audi brake light switch replacement but what do you mean 'if you use diag you will see' ? Also if switch is not 'set' correctly...can it be returned to factory 'new' position ?... once i have removed it off-course
Click to expand...

It can be carefully pulled out. The plunger has a thread inside it and slides over a thread on the pin it fits on. Can't be done to often though, if the thread gets worn it will not lock into position. Basically when the switch is as depressed as it will go, on it's stop, the the plunger should be touching the pedal. If you have that is should be fine. If you can push the plunger in with brake pedal fully back and there is a gap to the pedal it needs resetting. On diagnostics you should see one circuit being made and the other being broken. The two portions swap sense to and fro as the pedal is depressed or released.
 
Last edited:
Thanks Wammers... I've sent ya a private message after learning p38 had similar fault pre-christmas -before I bought it back. !.... Apologies Biastai for hi-jacking your thread
 
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