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I'm getting a P0640 (and now P0541, see below) on a 2001 Excursion, 7.3L
I cleared codes and P0640 popped right back up (plus P1000). I removed the wires from the IAH and reset codes, same result, plus a P0541.
Thinking I have a pinched wire somewhere, I purchased and installed RiffRaff IAH delete with "Air Intake Heater Plug Code Eliminator" and reset, same result.
I'm not sure if I have this thing installed correctly; all their instructions say are, "ALL YOU NEED TO DO IS REMOVE THE EXISTING WIRE FROM THE SOLENOID, THEN HOOK UP THIS WIRE AND RUN THE OTHER END TO GROUND."
Well, my IAH had two wires going to it: one red one going to what loks like a starter solenoid/relay and a black one going to an engine ground (stud holding the intake "plate" down.) With both wires removed I'm getting both P0640 and P0541.
Where does this "eliminator" go? Between that stud on the solenoid/relay and ground? What does that solenoid do?
I used the HPOP reservoir case under the engine cover bracket as the ground location for the AIH delete. I did have to clean the surface a bit before it tested good and installed the delete wire.
Below are a couple of borrowed images of how the wires are to be hooked up to the AIH relay.
Without going off memory and without going out to the truck to look at the eliminator wire, I know there are a few videos on YouTube that detail how to install the eliminator. I was going to link a couple, but they are easy to find and I didn't want to link one that might not work for you as the creator goes on to discuss other things that are not relevant to the title or video.
I have also attached the pinpoint tests for P0640 and P0541 just in case you wanted to look over them.
I removed the IAH power lead from its relay and I'm getting both P0541 and P0640 errors. If I put the RiffRff resistor between that power lead on the relay to a good ground (under the GP box), the P0541 goes away.
But I still have the P0640.
I'm figurung the P0541 comes from the PCM not seeing the resistance of the IAH itself. But I've yet to determine what is causing the P0640. Could it be not seeing the resistance of the relay solenoid? I guess I can break out the VOM to test that.
Note that this is the Excursion so I don't hve a standard GPR, I have the Cali glow plug box, whatver it's called.
I'm very confident it's not a problem with the PCM, as I just had that rbuilt by ChatDiesel.
Quick follow up to close this, in case anyone else is looking...it went away on its own. Which means it's not really fixed. I suspected maybe the PCM could tell if the relay was problematic but I never got around to testing that.
If (when) the code comes back I'll dink around with it, but for now...I've got other things to worry about.
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