international91 Posted November 21, 2005 Report Share Posted November 21, 2005 Help! The ABS light and the brake light stay on. By striking the motor relay the pump would run and the brake light go out but not anymore. Only occacionally those the pump run and the brake light go out. Could the culprit be the motor relay or the pressure switch? Any help greatly appreciated. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 21, 2005 Report Share Posted November 21, 2005 I duno if you have done it yet, but check the aux power, as this will come loose and one of the effects is making the abs light come on and stay on. Quote Link to comment Share on other sites More sharing options...
Prospeeder Posted November 21, 2005 Report Share Posted November 21, 2005 http://www.tpsgarage.com/TGP/brakes/powermaster.htm Pressure Switch: Bad switch can be indicated by a red light on the dash, no pump operation, frequent pump operation, pump not shutting off, pump running too long. Retails for $70 Motor Relay: Erratic Pump running, extended pump running, running while ignition is off, or not running at all. Retail $90. UPDATE! The relay now lists for around $300 . Unfortunately, the relay is NOT included with replacements from Prior. Quote Link to comment Share on other sites More sharing options...
LukeZ34 Posted November 22, 2005 Report Share Posted November 22, 2005 I've still got the relay off of that spare PMIII I have in the garage. You posted about it in the For Sale/Trade Forum a while back, in which I told you I'd look for and then never got back to you (sorry). If you (or anyone else) is intrested in it, PM me with an offer. Though, before I let it out of my hands, I'm gonna do some research and see if we can find a much cheaper replacement relay. $300 for a relay is pathetic. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted November 22, 2005 Report Share Posted November 22, 2005 I checked the schematic. The only thing special about this $300 relay? It's got 2 diodes and 1 10kohm resistor in it!!! It's a regular SPDT relay with 2 diodes in series across the coil. There is a resistor on one of the outputs that connects to the EBCM. The EBCM uses this to tell if the pump motor is turned on. That's it! If the existing relay has a 12V coil (not sure on this without measuring actual voltage going to the coil), a simple $10 Bosch style 40A relay and 50-cents worth of additional components is all you need to replace that $300 relay. Some cutting & splicing may be required to install a standard relay socket. I bet you can also fix the existing relay if it will come apart. I've taken apart bad relays and fixed them by cleaning the contacts. Quote Link to comment Share on other sites More sharing options...
international91 Posted March 15, 2006 Author Report Share Posted March 15, 2006 Troubleshot to a bad pressure switch. $187.00 plus shipping Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted March 15, 2006 Report Share Posted March 15, 2006 Damn old thread! Glad you got it fixed though. Quote Link to comment Share on other sites More sharing options...
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