shocker
Well-Known Member
Another session . Blinks 2/8 , inspect wiring and relay , clean contacts both ends , drive away , light out , back on after a minute or so of driving .
Back to blinks , read and clear 2/8,2/12,2/14,3/8,4/12,5/12,and another5/12 .
Drive away , light out , back on after same time .
Blinks , 5/12 ...intermittent fault with front right wiring or sensor . Great . Since rewiring and/or putting in new sections of wire can change resistance/impedence its generally not a good idea . So its back under the bloody thing and clean , inspect , remove , inspect , clean , re fit.......and back to the blinking blinks . From a cost point of view I have "pfta" as a donor and that had functioning ABS but , really.....bugger . I wanted to get on with the wheel arch and the head on "kart" . Sod it .
Back to blinks , read and clear 2/8,2/12,2/14,3/8,4/12,5/12,and another5/12 .
Drive away , light out , back on after same time .
Blinks , 5/12 ...intermittent fault with front right wiring or sensor . Great . Since rewiring and/or putting in new sections of wire can change resistance/impedence its generally not a good idea . So its back under the bloody thing and clean , inspect , remove , inspect , clean , re fit.......and back to the blinking blinks . From a cost point of view I have "pfta" as a donor and that had functioning ABS but , really.....bugger . I wanted to get on with the wheel arch and the head on "kart" . Sod it .
shocker
Well-Known Member
To revive this - the intermittant fault is truly intermittant .....some times I start the truck up and the light goes off and comes back , sometimes it stays on all the time , other times it works as it should and goes off after the prescribed time . I have noticed though , the times it works right are when I reverse out of a spot from starting , have a clattery ABS type braking effect then drive away to the light going off . I had though this was down to water in the wiring but the wiring meters OK and the same wet or dry . The fault can come and go on the same day - OK when leaving home , stop at the shop , light stays on when I start up again and move off . No real pattern .
Something my old dad suggested in one of his more lucid moments was that on the early lorry ABS systems if a disc was deeply scored then it could give this kind of fault . Now this could make sense as this fault is on the wheel where the pads had gone down to the metal and scored the disc ....so if that was the cause no amount of re sating the sensor would help .
Any thoughts before I have to go strip a set of discs off the spare (that had new ones 1k before it died) and swap them over , thus having to do the job twice , to keep the spare in rolling condition ...???
Something my old dad suggested in one of his more lucid moments was that on the early lorry ABS systems if a disc was deeply scored then it could give this kind of fault . Now this could make sense as this fault is on the wheel where the pads had gone down to the metal and scored the disc ....so if that was the cause no amount of re sating the sensor would help .
Any thoughts before I have to go strip a set of discs off the spare (that had new ones 1k before it died) and swap them over , thus having to do the job twice , to keep the spare in rolling condition ...???
shocker
Well-Known Member
No , that doesnt make any sense either , the sensor doesnt run on the disc , which is now smooth anyway (from new pads , I assume , unless the disc goblins have been at it with emery cloth) so that shouldnt make any difference ....
AND ....the fault code is 5-12 which on one list reads as "intermittant fault on OSF sensor or wiring" but on the WABCO book list reads " erratic signal on OSF " and suggests sensor position , bearing runout or tyre problem . Which is right ?
AND ....the fault code is 5-12 which on one list reads as "intermittant fault on OSF sensor or wiring" but on the WABCO book list reads " erratic signal on OSF " and suggests sensor position , bearing runout or tyre problem . Which is right ?
shocker
Well-Known Member
UPDATE : jacked up again and rocked the wheel - slight bearing play , enough to feel a tap either side , but to be honest , no more than on others that have not read this ABS fault . Oh well , its off with the wheel again and back to the bearing and tighten up . May as well have the ABS sensor off again and see what it does cleaned aqnd refitted again....again .
nrgserv
Well-Known Member
cant remember the code atm, but mine has the same on nsf. its a boroken wire at the sensor end and has the same synptoms as yours. erratic signal / intermittent fault.
meter the sensor and wiggle the sensor wire and see if your reading fluctuates. (think it should be somewhere between 500 ohm and 2k) reading should stay steady.
one day i'll get round to swapping it. ok if i set off forward, but as soon as i turn left i get the light on. wire currently cable tied to a brake pipe to stop it doing it all the time.
mine goes open circuit if wiggled in right direction.
meter the sensor and wiggle the sensor wire and see if your reading fluctuates. (think it should be somewhere between 500 ohm and 2k) reading should stay steady.
one day i'll get round to swapping it. ok if i set off forward, but as soon as i turn left i get the light on. wire currently cable tied to a brake pipe to stop it doing it all the time.
mine goes open circuit if wiggled in right direction.
Freediscoranger
Active Member
i agree. that sounds like the wiring itself is damaged and that's why its getting erratic signals. have you got the WABCO ABS fault code list? i would always go with what they say since they made the system..
nrgserv
Well-Known Member
linked the wabco manual earlier in thread
Richard Martin
Well-Known Member
Slight bearing play caused an intermittent abs fault on the ofs on mine (despite people on here saying it can't). After the front bearings were replaced on both sides I cleared the fault and it never came back.
shocker
Well-Known Member
Yes , I printed off the Wabco doc whole and have it with my service manuals . Its from there that I got the wheel bearing thing from ....which threw me a bit as I had put it down to wiring until then . I belled it through with the meter early on is this fiasco/sequence of events and got the correct numbers (whatever they were) but didnt wiggle or wet , which seems to be a cogent point . Got some welding to do then I will have the lot apart and do the wheel bearing , re fit the sensor and look at the wiring at the same time . Thanks everyone .
