Electrical/Wiring Guru's Please Double Check
 

Hi,
I will try to make a long story short. I have a 2000 LQ4 harness that uses a 2 wire high pressure switch that is located in the Truck Compressor. I bought a 2 wire Vintage Air trinary switch that is a high and low pressure switch. My issue is that I believe the Truck Hi pressure switch's circuit is open when pressure is good and the VA switch is closed when pressure is good. I have read that you can use a relay to change the circuitry of a switch. Please check out the schematic below and let me know if I have this figured out correctly. If I have it right, is there any chance of damaging the trinary switch by running the current from the relay through it?

http://www.robbieday.com/photo_galle...ac_done_sm.jpg

If I have this correct, I plan on doing the same thing for my brake switch which the 2000 LQ4 PCM wants power when the brake is not in use and my chevelle brake switch does the opposite [I believe]

Thank You for any help.

Rob

That looks good if the ECM needs to see an open when the pressure switch is happy, if that is what you are after. The same type of wiring will be fine for your lockup stuff too, I usually do them that way.

pin 30 keyed +
pin 86 power from brake switch when pedal is pushed
pin 87a output for lockup
pin 85 ground

Why put a relay on the brake light switch, just get a switch for a car with cruise control, it has 2 sets of contacts one set normally closed for the cruise control and one set normally open for the brake lights

Thanks for the input guys, I appreciate it

Poconojoe, good info. So......what "cruise switch" will fit in a '67 Chevelle?

Thanks

Rob