2001 Olds Intrigue Air pump relay

[sideking]

Any ideas on why my PCM will not throw an enabling ground to my air pump relay at cold start? Tests so far:

1. Start cold engine. Secondary air injection pump does not come on.

2. Position air pump relay at half-plugged in, enough to expose plugs but not enough to break contact with relay jack. Switch ignition to ON. Ground relay coil to battery ground. Air pump comes on.

Probably need to check if PCM is getting accurate engine temp read. Anyone know the procedure for that?

 

[sideking]

Okay, engine temp was fine. Pulled the PCM and set it on the bench. Began testing for shorts in PCM socket harness C2 (Clear) with IGN OFF. I connected one VOM lead to pin 75 and rotated the other lead around to each of the other sockets. I found continuity between pin 75 and the following pins:

2 - Evap can vac sol switch
37 - O2
42 - Fuel inj #4 control
48 - The Connector Pin guide on Autozone's website says this socket is not used. But there's a socket there with a brown wire attached. Now I wonder if this is the only misnomer in the guide. It also lists pin 60 as PCM ground, whereas I believe on the Intrigue harness PCM ground is pin 63.

78 - Torque Converter Clutch Pulse Width Modulator (TCC PWM)

I began searching for your garden-variety short between pins 78 and 75. I figured these would split at the junction near the top-left radiator, and they did. When I pulled them apart, no contact whatsoever, continuity remained.

Next I pulled fuses associated with each circuit. When I did so, continuity went away on the circuit associated with the fuse I pulled and remained between the other pins. So now I'm thinking about backfeed through solenoid coils, which are after all just long conductors (wires) wrapped around a shaft (simple motor). Will the continuity go away when I apply voltage to the other side of the wire? Will the pins all go hot (batt voltage)?

Which leads to the real question: If I test with IGN ON while PCM is removed, is there any way I could damage these circuits?

 

[sideking]

Oops, forgot to mention...

...getting code p418.

 

[sideking]

Couldn't wait. Took the plunge and applied voltage. Tested with IGN ON. C2 sockets with relays attached went high. Looks like solenoids were backfeeding through the fuse panel to a common terminal which is why I was getting continuity. Removed voltage. Tested wire between AIR pump relay and pin 75 for continuity. Strong signal with little to no resistance. I'm calling the PCM bad and ordering a stock replacement from Flashmasters on ebay. Will let you know how this works.

 

[sideking]

Just wrapping this up

Turned out to be a bad Air Pump check valve on right side of motor (closest to firewall, of course).

Before I determined the failed part, I got stuck thinking it was the Air Pump itself. Funny how stubborn you become when you think it is a simple fix. Stubborn to the point of being willing to throw good money away. Heck no, I don't have to do any circuit research. Circuits shmircuits, it's got to be that doohickey over there that's making all that noise. In the meantime, in addition to completing my preparations to burn cash, I had to figure out how to get the computer to throw a ground to the Air Pump motor, so I purchased a used Delphi PCM from E-bay programmed for a 2001 Intrigue. My OEM PCM was a Delco, so I had my doubts, but after I installed the new-used PCM, the Air Pump fired right up at cold start squealing like a pig on a gate. This was a brand new re-manufactured from Card-One Air Pump that I bought while I was being stubborn and wasting money throwing parts at the car. New part, same symptom, back to the drawing board. Only parts left were vac solenoid, vac lines, and vac heads on the check valves. The vac solenoid clicked sharply when grounded with KOEO. The vac lines to and from the solenoid tasted yummy when they held vac. The single line to the left check valve (please let this one be bad, I don't want to go to the dark side) held (crap). But the line to the right check valve wouldn't hold. Dark side it is. I replaced both check valves in case you were wondering. They have them at Rockauto.

I kept the old Air Pump instead of turning it in for a core charge because it sounded like the pig's brother when it was on the car, but it was nice and quiet when it was plugged into the circuit while sitting on my garage floor. Now I have a spare. I consoled myself by saying at least I didn't buy a new vac solenoid.