ABS fault

IamNotAllowedToUseMyName

mro wrote: »

Are ABS faults read via car diagnostic plug & engine ECU ?

Car wiring is different from the old days. Rather than lots of wires going to each individual part, cars have a network, so lots of components share the same wiring loop. The ABS controller will be on the car's network and so will be accessible to the diagnostic plug.

The diagnostic tool designed for the car will know the codes to send round the network to talk to different kit. There are a number of standards, and there are variations of components, so the proper diagnostic kits essentially have a database of equipment and how to talk to them, whether they are brand specific tools or 3rd party tools, and they can detect what is there and know from model variant what should be there. These bits of kit from 3rd party are £10k+ and provide a support network to independents and keep them up to date. Any serious independent will have one of these tools, you can't work on a modern car without something that can talk to the whole car properly.

All in all quicker and more accurate to diagnose with a bit of that kit than an Internet forum

mcpitman

Johnmcl7 wrote: »

What car and how old is it?

Agree this information would help...

mro

Johnmcl7 wrote: »

What car and how old is it?

mcpitman wrote: »

Agree this information would help...

It's an old car, 1995 Vauxhall Cavalier 2.0i 16V.

Uses an old type 10 pin diagnostic plug.

AdrianC

mro wrote: »

It's an old car, 1995 Vauxhall Cavalier 2.0i 16V.

Ah... There's quite a bit I very nearly typed with caveats "...but that'd only apply to old stuff..."

Right, forget all the diagnostic stuff. That old? Pre-OBD. Pre-standardised diagnostics. Quite probably pre-ABS diagnostics of any kind. It might just be down to multimeters.

s_b

AdrianC wrote: »

Ah... There's quite a bit I very nearly typed with caveats "...but that'd only apply to old stuff..."

Right, forget all the diagnostic stuff. That old? Pre-OBD. Pre-standardised diagnostics. Quite probably pre-ABS diagnostics of any kind. It might just be down to multimeters.

at least it doesnt have elastic bands going to the driveshafts like old hescorts:D

i would do the relucter ring then take it for a drive if it was my cavvy

Strider590

No two ways about it, if the ring is broken then it WILL cause an ABS fault. It'd also cause a traction control fault if it's broken on the driven wheels and your car has TC of course.

colino

While diagnosis by internet is deeply flawed and if the reluctor ring is cracked or rusted out, it does need changed, it still doesn't tally with the light coming on and staying on. The abs system, even in a middle-aged v/x, will run through its self-checks on start up and should go out if its the ring. On driving it should then detect an implausible signal (the broken reluctor ring wheel not tallying with the other wheel signals) and then put on the light.
Hopefully just a confusion of description rather than another fault.

s_b

colino wrote: »

While diagnosis by internet is deeply flawed and if the reluctor ring is cracked or rusted out, it does need changed, it still doesn't tally with the light coming on and staying on. The abs system, even in a middle-aged v/x, will run through its self-checks on start up and should go out if its the ring. On driving it should then detect an implausible signal (the broken reluctor ring wheel not tallying with the other wheel signals) and then put on the light.
Hopefully just a confusion of description rather than another fault.

with it being first generation im not convinced with it being a vauxhall too that the light wouldnt stay on till cleared,
anyway i found this link to do the old split pin check that must be a good 10 years since i last did it as it was easier to use the old gunsons tool from halfords
use with caution OP
http://everything2.com/title/How+to+read+ECU+fault+codes+from+some+GM+cars

mrmechanic

If the reluctor ring has split, then it will more than likely have taken out the wheel speed sensor .
The air gap between the ring and the sensor is very small, the reluctor ring usually splits due to the cv joint corroding and swelling.
This causes the reluctor ring to wear through the speed sensor as the air gap reduces until it goes open circuit.
Op need to carry out resistance test on the speed sensor on the corner with the broken reluctor ring.

mro

I've found what problem was.

One of plugs wasn't fitted properly, was very loose when I took cover off relays/electrical components control unit box.

I think this is a 4 pin plug that supplies power to relays/abs power electrics.

There is another multi pin comms type plug that plugs in next to this box/cover, which was plugged in.


I'd forgotten I'd disabled ABS last year as I was getting brake judder, I think because of the corroded, possibly broken reluctor rings, I saw somewhere on net that broken rings can cause this. When I disabled ABS, brake judder stopped.

Now I've plugged both ABS plugs back in, ABS light does go out, but now got same brake judder again, so will get that sorted.