I'm able to read Pending and Trouble codes via VPW, but I can't seem to clear them.
I send this packet:
68, 6A, F1, 04, CRC
The ECU responds with
48, 6B, 10, 44, 52
Clearly the ECU got the packet and it has responded....Seems all is well.
But I if I then check the codes again, they are still there.
Note that I removed the fault condition before attempting to clear the codes.
Is this a case of a VPW ECM not supporting this function?
I have tried it on a 1997 Saturn SL and on a 2003 PT cruiser..(Ya, weird that the Crysler uses VPW) Can't clear the codes on either.
Looking closely at the Standard J1979, it actually says that "All ECUs shall respond to this request". But it does not actually say that it must carry out the clearing process.
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No response to 1C
48,6B,10,44,52 (Clear Codes response)
Whenever a DTC is hard and present it always looks you can't clear the code.
In fact you do clear it, but before you can read the codes the ecu has reset the code.
Also, from my limited testing, it appears that the ECU is only checking for the fault at power-up. If I introduce the fault after power up, no code is posted.
So what do you think? Is there something wrong, or is this just how these older VPW ECUs operate?