First off, I'll apologize for cross posting this into a few categories, as I'm not sure where this question really belongs. I'm nearing the end of a TBI to TPI swap into a 1993 Caprice wagon.

Specifically, the wagon had a wire going to the power steering pressure switch, which I cannot find a home for. I can't find a pin reference on my 730 ECM that relates to a power steering connection. Since others have made swaps, I'm hoping someone has been down this road before to enlighten me.

Thanks, Dave

 

The power steering pressure switch function may determine how much effort you want to put into finding a place for it on the 730 ECM. The switch is designed to signal the computer that there are higher pressures present in the hose (IE turning the wheels), in response, the ECU will bump up the idle speed to compensate for the added engine load. This would only be needed at low engine speeds (IE turning in a parking lot), but could be overcome by increasing the idle slightly.
Remember the OEs strive to attain the lowest idle speed possible, and then bump it up only when needed as low engine speed loads increase. (a/c compressor cycling, power steering switch cycling).
I no longer have the TBI harness in my '88 Trans Am, but I can say my '03 Lightning would stall at parking lot speeds, when turning until I raised the “idle speed in gear” setting by only 50rpms.

 

Very good reply! ^^^

I was going to say the same...

 

Thanks to both of you for the explanation of what it is for. I thought it actually controlled pressure, hence the name "Pressure Switch" I didn't know it was idle related.,

A s to an answer to the question of "where does it go", Sixshooter responded to one of the cross posts with pin "D13.. The reference doesn't seem to be listed in every application... same as a 7749 ECM"


Thanks again to all, Dave.