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PMIII parts availability


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Hello all,

 

I still have my 1990 TGP, been driving it off and on but it mostly sits because PMIII has been acting up. I was wondering if there is still a place you can purchase any of these parts new? I would like to get a new pressure switch for it. If any of you have a good used one laying around I would take that off your hands as well though. I plan on also replacing all the relays on it. Motor is still good and so is accumulator.

With my second Gen GTP blowing up the other day I am parting it out and might as well put all my efforts into this car. Thanks for any and all input!

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Glad you're keeping it, Luke. I can get a good pressure switch out to you asap. You will not find them new. Let me know if you want it. I still have the one I was going to send you once before.

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Yes I should go ahead and scoop that up, PM me the details on price and such and I will get it paid for.

 

I took a hiatus because I wanted to focus on my sencond gen drag car, well that just blew up. So its going away for good and the TGP is going to get some love. How is yours coming along?

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Good luck on new parts.

 

I modified a relay to use a regular relay so no more hard to find crap for that.

 

But the other parts, good luck.

 

A few years ago I was close to coming up with alternatives to the pressure switch, but I've since forgot everything and will have to start over.

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I know there are grand national pressure switches that look close to ours. Also are you telling me the relays are a special type??? That sucks, I was going to replace all of them when I did the pressure switch just to have piece of mind. Could you link me to how you modded them possibly??

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Basically I took a dead ABS relay and cut it open. But first...

 

The PMIII relay is essentially a regular automotive relay with a few exceptions. Its proprietary connector most obviously. It also has a few diodes in it and a resistor to drop the voltage on one pin down to 5v and the diodes insulate the circuit so the EBCM 1 knows when the pump motor is running and 2 that motor feedback does not get into the EBCM

 

That said, I cut the relay open and carefully cut out the relay portion of it. I purchased some relays and relay pigtails from Parts Express and drilled a hole in the side of the relay casing used a rubber gromet to seal the wires off from the outside and soldered the 4 wires of the relay to where the old one was. I forget exactly what I did as its been a few years and you have to get the polarity of the trigger correct as the diodes will otherwise prevent it from working if its backwards.

 

But the end result is a setup that relocates the relay further up and the ability to use cheap commonly available parts.

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All I've ever had fail on relays has been bad connections from corrosion on the contacts for the arm inside causing it to either stick on or open circuit. I've been able to fix them by just opening it up, sand on the contacts, spray it with electrical cleaner, and reassemble.

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GN pressure switches will not work. That system operates at much lower pressures than ours. Lotus owners have had some luck with removing and cleaning the pressure switches. GnatGoSplat made a post about that here a few years ago. If you can't locate it, let me know and I'll find it for you.

 

Some Teves units have pressure switches that at least cut off at very close pressures to our own. I have no idea if the design or threading is anywhere near ours though. I will make it a point next time I visit the junkyard to grab a pressure switch from one if I come across a teves unit. I know we will eventually need an alternative if we keep these cars on the road long enough. I myself do not want vacuum brakes unless that's a last resort.

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  • 2 months later...

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