abs/tc lights on

my cousin bought a 98 p38 2.5 with these lights on. he got it plugged in to diagnois fault, not a dealer system. it said rear sensor fault, replaced sensor , lights still on. t guys computer can not turn off t lights. does anybody know or have any info that might help us,dealers 100 miles away and greedy. thanks

Bit strange that the chap with the diagnostic kit can identify a rear sensor fault BUT not be able to rest the system. In fact normally getting a new sensor fitted usually clears the display message without needing a computer reset. So what has gone wrong? It would be interesting to know what diagnostic kit this chap has?
a) When you fitted the new sensor did it show up on this chaps diagnostic software as giving the correct voltage back to the ECU for that wheel. If it did then one of the diagnostic systems (testBook, Autologic or Rovacom) should be able to clear the fault. If using one of these diagnostics won't clear it a permanent fault is recorded and you may need a new ECU

b) was the correct sensor fitted - they changed around 99. Also you say a rear sensor but don't say which one?

will have 2 check was it t correct one or where he got it. it was t back left. the guy who tried 2 clear it came up with an open brake switch circuit , but t brake lights work properly, all sensors were reading correct at that time. thanks

stopover said:

Bit strange that the chap with the diagnostic kit can identify a rear sensor fault BUT not be able to rest the system. In fact normally getting a new sensor fitted usually clears the display message without needing a computer reset.

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I agree, the ABS system does a self-check when you start the vehicle and drive off, so any fault should be cleared automatically rather than having to be cleared by the diagnostics kit, which suggests that there is still something wrong!

mmaddock said:

I agree, the ABS system does a self-check when you start the vehicle and drive off, so any fault should be cleared automatically rather than having to be cleared by the diagnostics kit, which suggests that there is still something wrong!

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Yes,the brake switch - it doees more than put the lights on.if you watch the switch states as live data you should see switch 1 open at rest and 2 closed.As you press the brake pedal,1 should close then 2 should open.(Could be the other way round,but you get the idea) If the ecu does not see this it simply cant tell when its supposed to be working.