Re: P1538 Stumper; IMRC Stuck Open?
Ok, for anyone that is interested, I had time to look further into this weekend, here's what I found:
I re-checked what I had previously verified, that is, that the actuators did in fact open and close when they should, and that the linkage and such was not in any kind of bind. I also went to the library and got a hold of an engine wiring diagram that shows the IMRC sensor circuits.
I cleared the P1538 code and then I swapped the plugs around, that is I put the plug from bank 1 on the bank 2 actuator and vice versa. Then I drove the van to run some errands. The check engine light came back on after some drive time so I went to AutoZone to have the code read. Guess what?
It was a P1537 (which is Intake Manifold Runner Control Stuck Open (BANK 1). (BTW, IF you have AutoZone or someone else read your error code be sure to get the alphanumeric code and not the description for them, different code checkers have different descriptions, and they wanted to sell me a new Idle Air Control, which was not the problem.)
Went back to the house and got out my meter, unplugged the electric plug for the sensors, and read resistance across the sensor terminals. Bank 2 sensor did not have the same readings as bank 1. So I feel 99% sure that both IMRC's work mechanically correctly, its just that bank 2 sensor is cooked and tells the computer there is a problem. So now I get to try and find a cheap IMRC for bank 2.
Hope this helps some one else.