So after a lot of diagnosing and replacing the ECU for the ABS, I finally determined that the pressure switch is the culprit. This was tough to diagnose and this is what led me to this diagnosis. When the ignition is turned on (2nd position), power is fed to the ABS ECU via two main wires, Pin 2 is the main power, this is fed to pin 8 internally and then fed to the main ABS relay control (coil) . This was not happening, leading me to believe the ECU was this problem. I replaced that (with a used one) and the same issue persisted. So I removed the ABS relay and tested the pin 8 output power to the relay...it was there!, but when I carefully inserted the relay into its socket, the relay would momentarily activate, then turn off. So I started running though the diagnostic procedure that dealt with the booster pump and such. When I finally got to testing the pressure switch (after confirming the booster pump was active and turned off at pressure) no continunity to the ABS ECU pins 9 and 10. So are these switches serviceable ( they don't appear so). and does anyone have a spare? Part number JLM1908.
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monkfe,

I don't have a spare, but great work on the diagnosis. The pressure switch is not a common failure issue, but it can be quite problematic to diagnose with people often thinking it must be a pump fault or an ecu issue. Well done and I'm glad you're moving forward to resolution.

Cheers

Paul

 

Hello,

I have a used switch.
I sent you a private message.
Rob

 

Thanks guys for the support and offer. I wound up finding one on ebay with the whole assembly for a reasonable price. Now I have an extra pressure vessel too.