Mk6.5 Fiesta ABS fault
Discussion
Hi all and hope you’re all well.
Been running a very cheap 1.25 2006 Fiesta for the past 3 years, though now has an ABS light and an MOT due very very soon. Don’t want to pay a garage as the car is worth less than a repair, though I’m quite keen to keep it from the scrapyard as the rest works perfectly.
Quick disclaimer - had it on multiple scanners, from high end to low end, and it only gives a connectivity (U) code. Doesn’t give any clue as to where or what a fault is, just that the ABS system has one.
I took a multimeter to each front ABS sensor, and both tested as working. The wiring for each rear sensor meets in the middle of the rear axle, and connects there with a 4-pin plug, with separate pins for each side. The multimeter told me that neither rear sensors have any reading … very unlikely that they both failed, so it tells me that it is likely a fault in the plug wiring which has cut off connection to both sides. It is one sealed unit which I didn’t want to chop up, so found a tested replacement from a breakers yard for cheap. Tested with a multi meter and all good.
I unplugged the old sensors and plugged in the new one without fitting anything and the light stayed on. Removing the old sensors would require a lot of effort and a very very high chance of shearing/rounding the bolts which house the sensors. So I’d rather make sure it was that before having to tackle it. I think I’ll leave it overnight with the new one plugged in and the battery out… will it likely show a fault just because the sensors plugged in aren’t installed into the hubs? In my head, sensor reading at a standstill will be the same whether loose or installed… but would like a second opinion.
I’m told it can’t be the module as the speedo works, and it is fed off the ABS on these.
Thanks in advance.
Been running a very cheap 1.25 2006 Fiesta for the past 3 years, though now has an ABS light and an MOT due very very soon. Don’t want to pay a garage as the car is worth less than a repair, though I’m quite keen to keep it from the scrapyard as the rest works perfectly.
Quick disclaimer - had it on multiple scanners, from high end to low end, and it only gives a connectivity (U) code. Doesn’t give any clue as to where or what a fault is, just that the ABS system has one.
I took a multimeter to each front ABS sensor, and both tested as working. The wiring for each rear sensor meets in the middle of the rear axle, and connects there with a 4-pin plug, with separate pins for each side. The multimeter told me that neither rear sensors have any reading … very unlikely that they both failed, so it tells me that it is likely a fault in the plug wiring which has cut off connection to both sides. It is one sealed unit which I didn’t want to chop up, so found a tested replacement from a breakers yard for cheap. Tested with a multi meter and all good.
I unplugged the old sensors and plugged in the new one without fitting anything and the light stayed on. Removing the old sensors would require a lot of effort and a very very high chance of shearing/rounding the bolts which house the sensors. So I’d rather make sure it was that before having to tackle it. I think I’ll leave it overnight with the new one plugged in and the battery out… will it likely show a fault just because the sensors plugged in aren’t installed into the hubs? In my head, sensor reading at a standstill will be the same whether loose or installed… but would like a second opinion.
I’m told it can’t be the module as the speedo works, and it is fed off the ABS on these.
Thanks in advance.
vw_99 said:
Has the battery went flat recently?
Thanks for the replies. The battery was replaced over a year ago and hasn’t gone flat since. I was under the impression that the sensors would only throw an error once the brakes had been used after a reset. Will connect the battery up and see whether the code is there tomorrow… and connect up the new sensors either way!
After plugging in the sensors without fitting them and clearing any codes the ABS light should come on with ignition and extinguish once the ECU has registered the sensors as being in the circuit, I can't remember if the engine needs to be started to extinguish the light if all is good, you will know though
Driving the vehicle to turn the wheels is for testing that the sensors are producing signals from the teeth moving past them and that's not the fault you are trying to solve. Driving the car for testing the ABS comes later
Driving the vehicle to turn the wheels is for testing that the sensors are producing signals from the teeth moving past them and that's not the fault you are trying to solve. Driving the car for testing the ABS comes later
Edited by Penelope Stopit on Saturday 8th January 08:04
Well as you have been told above, you can't rule out the possibility that you have found the issue as the ecu NEEDS to see good signals before it will clear a code for the sensors.
As above you need to fit everything correctly & take it round the block rather than keep (potentially unnecessarily) firing the parts cannon at the car.
As above you need to fit everything correctly & take it round the block rather than keep (potentially unnecessarily) firing the parts cannon at the car.
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