abs light on, cannot clear fault code

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R

Rayg

New Member
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4
Location
Karitane nr Dunedin, NZ
1997 300 tdi auto in deepest darkest New Zealand; replaced brake switch after failure and ABS light stayed on. Did blink analysis using the 5;15 bridging in previous forums and fault code 2;6 came up (brake switch). Cycled the blink codes 3 times and then broke the bridging in the 4th cycle; but the light stays on, still only the one code 2;6. Have I missed a step in the code clear process ?
 
Short the pins, watch the blink code, remove the switch, wait for blink codes to stop and a steady ABS light, then turn the ignition off. Then ignition back on, short the pins again. If you get the same fault code then it's called a hard fat and you haven't fixed it. But it should then read a new code. Do this till all you get is a 1-1 constantly. Then you've cleared all codes
 
I'm also in darkest nz, I second the post above the key is to either power off or disconnect the pins at the right time in the blink cycle....otherwise the fault does not clear.
 
Accessing trouble codes
Ensure ignition switched OFF.
Remove ABS warning lamp relay.
Switch ignition ON.
Check warning lamp illuminates.
Bridge diagnostic socket terminals 2 and 5. A: Fig. 3
Bridge data link connector (DLC) terminals 4 and 15. B: Fig. 3
Wait 5 seconds.
Warning lamp extinguishes.
Warning lamp starts flash sequence.
Compare with trouble code table.
Erasing trouble codes
Access trouble codes.
Disconnect diagnostic socket or data link connector (DLC) bridge wire Fig. 3 .
Trouble code will be repeated until code erased.
If more than one trouble code has been flashed, reconnect bridge wire Fig. 3 .
When last trouble code flashed, remove bridge wire.
Refit ABS warning lamp relay.

1. did you remove the relay?
2. did you fix the fault

otherwise it will stay on
 
Last edited:
sf, you dont need to remove the relay.
what i suspect is happening, is there is more than one stored fault of the same type.
delete one, it brings up the next (which is the same fault logged). could be loads of them!
not sure if op's vehicle is moving or blink code testing when he says light stays on.
cant remember off top of head what blink sequence is on ignition turn on, to indicate stored faults or clear of faults.
think a steady light from turn on has stored faults, a short blink from turn on is clear of stored faults. might have this the wrong way round tho......
 
You got that the right way round. And no you dont need to remove the relay.

Check the codes as they flash since it shouldn't be the same code should always read a different one of you do as said . If the same code repeats it means it's a hard fault and you still haven't fixed it. But watch them flash you may be getting a 2-12 then 2-13 and a 2-11 for example....
 
Thanks guys. I did not remove the relay, and only bridged 5 and 15. It may be a hard fault - but we have just put in a new brake pedal switch so should be OK (there was no fault before the switch failed and then the only code I have brought up is 2;6 which is the brake switch, no other codes shown). Will re-try tomorrow, will remove the relay, then bridge terminals 2 and 5 and then 4 and 15 and try to remove the codes, and will advise
 
ImageUploadedByTapatalk1346479981.481196.jpg

Hope you can see that okay. That's the page from the wabco manual for fault codes
 
bear in mind that even if you've swapped the faulty brake switch, there could be hundreds of stored faults from every time you pressed the brake while the fault was active.
might be worth introducing a fault to prove the abs ecu logs a different fault, ie disconnect a wheel sensor and drive, let it log an open circuit fault, check fault code to see if it logs it, then see if your brake sensor stored fault returns.
then keep deleting them.
what i dont know is if faults can be deleted en mass by autologic, testbook or similar.
would be a lot easier!
hope this helps.
 
Well the problem is solved thanks to you all. There is now light in deepest NZ. The key is the relay.
Process followed as in notes by sierrafery and the Wabco manual above. In summary I;
1. disconnected the ABS relay under passenger glovebox
2. bridged terminals 2 and 5 and 4 and 15
3. turned on ignition and watched blink cycle (long, short, gap, 2 short, gap, 6 blinks (the code can be other numbers of blinks)
4. as the code cycled for the second time I disconnected the bridge wires then turned off the ignition
5. turned the ignition on again and light behaved normally (on/blink/on again until car reached approx 5km/hr and then off permanently)
6. re-connected relay (remember for those following me I had done all this without disconnecting the relay and had not cleared the fault code).
In the various instructions there wre none for finding the relay so here goes;
- passenger footwell under glove box
- remove cover
- see relays etc on left side
- there is a metal 'tray' of relays lying flat in the centre and on their right a set of relays on the diagonal
- undo the front bolt and lower the tray
- the relay you want is the second one in (2 tone green) and the 4 wires are 2xblack, 1 x black/green, 1 x brown/red
- separate the relay in the middle (it pulls apart)
So again a heartfelt thanks for the help
 
i attach you the whole diagnostic procedure for Disco 1 ABS... never mind it says V8...the ABS is the same for all
 

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