Persistent ABS/VSA faults

[pintofale]

Morning all,

I have had intermittent ABS and VSA errors for weeks now.  First I thought it was related to a low battery, and charging the battery did clear the faults, but they came back.  Then I persuaded myself it was a wheel sensor, because I had ABS cadence braking on the front offside wheel only, under light braking.  The faults cleared with a new sensor, but came on again a few minutes later when driving.  I've also tried the trick I found on youtube where OBD pins 9 and 4 are linked and a sequence with the brake pedal is followed to clear the ABS error, but this didn't work, which suggests I have another problem.  But it did show me a series of error codes on screen which didn't show with my ebay OBD scanner, these were B1241 (which is apparently blower motor related), B1239 (climate control), B1133 (also climate), B1232 (climate again) and B1169 (gauge control module), none of which seem to relate to ABS or VSA.  I have to get it resolved soon as my MOT is coming up.  Any advice or suggestions much appreciated!  I should mention that prior to changing the wheel sensor the faults were intermittent, sometimes it would start with no fault and they would come on after a while.  After changing the sensor the faults were also off for a while, but once they returned they now seem to be on constantly.  But it seems unlikely the sensor worked for half an hour and then failed.  And it has cured the cadence braking on that wheel.

[Pegasakidis]

What about the wiring close to the sensor?


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[pintofale]

I pulled through as much as I could when I changed the sensor and it looked ok.  I think it would need to go up on a lift and have the engine cover off for further checks so a garage job.

[embee]

Without access to more detailed diagnostics, my first suspicion would be one or more of the other ABS sensors.
I know what dealers can be like but when a friend's Merc had a similar ongoing ABS light issue and an independent place failed to fix it,  the Merc dealership sorted it with 2 new sensors . They said they always changed them in axle pairs as a matter of course.

[madasafish]

Are the tyres worn the same of opposite side wheel?
Rusty ABS  rings on  driveshafts can give false reading.
You can check sensors and wiring with a  multimeter: checking resistance and for  open circuits.
You can also check ABS rings by  measuring current on wiring. (all assumes simple knowledge of electrics)
Been there sorted it all with multimeters.

[Westy36]

Lot's of help above. However, just a thought....

First I thought it was related to a low battery, and charging the battery did clear the faults, but they came back.

I'd get your battery properly tested at a garage. Could well be on it's last legs, and garages have devices that can properly check battery health. If you've a breakdown membership, and I've done this before, call them when away from home and see if they'll help. Some patrol persons can be really helpful.

Earth strap is worth checking if electrical faults.

If it does turn out to be a faulty abs pump, I've used these folk before https://www.ecutesting.com/product-catalogue/honda/jazz/abs-pump-ecumodule-combined/

They said they always changed them in axle pairs as a matter of course.

Useful knowledge. 

[pintofale]

Thanks for all of the advice!  The battery should be good, it's less than two years old.  But the car is 13 years old and so the sensors or rings could be the problem.  I will get the DVM out and compare the two sensors on the front axle - one new, one old.  I doubt it's an ABS unit failure because I also have the VSA fault, but I don't know how the systems interoperate. 

[Pegasakidis]

the 2 systems cooperate together and share the same sensors

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[jm0128]

Morning all,

I have had intermittent ABS and VSA errors for weeks now.  First I thought it was related to a low battery, and charging the battery did clear the faults, but they came back.  Then I persuaded myself it was a wheel sensor, because I had ABS cadence braking on the front offside wheel only, under light braking.  The faults cleared with a new sensor, but came on again a few minutes later when driving.  I've also tried the trick I found on youtube where OBD pins 9 and 4 are linked and a sequence with the brake pedal is followed to clear the ABS error, but this didn't work, which suggests I have another problem.  But it did show me a series of error codes on screen which didn't show with my ebay OBD scanner, these were B1241 (which is apparently blower motor related), B1239 (climate control), B1133 (also climate), B1232 (climate again) and B1169 (gauge control module), none of which seem to relate to ABS or VSA.  I have to get it resolved soon as my MOT is coming up.  Any advice or suggestions much appreciated!  I should mention that prior to changing the wheel sensor the faults were intermittent, sometimes it would start with no fault and they would come on after a while.  After changing the sensor the faults were also off for a while, but once they returned they now seem to be on constantly.  But it seems unlikely the sensor worked for half an hour and then failed.  And it has cured the cadence braking on that wheel.

What was the answer ?

[Lord Voltermore]

The OP referred to an 'ebay  OBD scanner '.  Many scanners can only read engine codes, not ABS and others. 

I had an abs fault on a Corsa. I took it to an independent mechanic who was very experieced in brake work.  His scanner couldnt read it so he called over a friend from an adjacent garage - which was a main dealership, whos scanner diagnosed a faulty  abs wheel sensor.   (Turned out the sensor  wire had been chewed  by a mouse!  )

Although I told myself had I noticed the mouse damage I could have changed it myself  But  I watched him do the work and realised It was probably a job best left to an expert with the correct equipment.    The wiring connector block was of a type I was not familiar with and that needed experience to disconnect and reconnect securely   and the wire itself had an extremely fine electrical filament.  IIRC it was a single strand of wire.  Easily damaged ,either in service, or during  inexperienced fitting.         

On the same corsa I had some strange engine behaviour that turned out to be the battery. The engine ( a diesel) would start for a second but immediately cut out .   It would sometimes continue to run and settle down if I kept my foot on the throttle.

I was pushing my luck with the battery, which was original from new  - now 13 year  old     Until that moment it had always shown over 12v at rest    and had enough oomph that the engine always started immediately even at minus 20c.    But with the  starting trouble I realised it had nothing in reserve for any extended cranking  and the voltage would fluctuate, sometimes dropping so low it affected the cars  security system and sensor readings. .   A new battery fixed it.   

[pintofale]

Sorry for the delay in replying.  The issue was fixed by the garage - it was apparently debris on the magentic ring in the hub, so I guess I must have disturbed something when I changed the sensor.  Bit annoying really as I could/should have seen it and sorted it myself, but there we go.  However, I am not totally happy with the new sensor - occasionally when I brake (lightly) I get "one click" on ABS on that wheel.  No ABS light, just the ABS working for a fraction of a second.  It passed the MOT ok, but I am considering buying a new sensor.  I confess I bought the cheapest one off ebay - can anyone recommend a good brand please?