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Discussion Starter #1
Hello everyone
I installed a DPC 422 PCM in my 97 so i could run a 4R100. i cant do a CCT due to two codes i have. they are AIH codes P0541,P0640.
I used a E-99 spider and did not install a AIH relay. Their are 3 circuits from the AIH relay to the PCM. does anyone know if i could trick one of circuits with a resistor so i can run a CCT. If so what circuit and what value resistor.
thanks Bill
 

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Not that I know anything regarding the heater and relay (so take any suggestions below with a huge grain of salt … I don't want to fry your PCM!!!), but here are the possible causes
for each code (I found this elsewhere as my 1999 PCED had no tests for the P0541 and the P0640 was totally wrong!):

P0541 Manifold Intake Air Heater Circuit Low Voltage
possible causes
MIAH circuit is open or shorted to ground from relay to the PCM
MIAH heater relay power (12v) circuit is open to the Alternator
MIAH has failed
PCM has failed

P0640 Manifold Intake Air Heater Relay Circuit MalfunctionPossible Causes
MIAH relay circuit is open, shorted to ground or to power (B+)
MIAH heater relay power (B+) circuit is open to the Alternator
MIAH heater relay has failed
PCM has failed

I think you would probably need to fake that the relay's coil is there first (maybe use the resistance of a GPR coil in the circuit between pins 71/97 and pin 98. I'd see if that gets rid of one (P0640) or both of the codes. P0541 might come back if the conditions are met for turning the heater on. If that's the case, you might have to figure out how to do the mod described here: 7.3L Power Stroke Air Intake Heater Delete Information (IAH/AIH) but you won't have a relay to connect to (and I don't think you'd want the resistor mod in the link to be "HOT" all the time if you hooked it between 12V Hot and ground). I read where many folks use a GPR (like a NAPA GPR-109) for that relay if you were going to put one in place. Cheers!
 

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Discussion Starter #3
Thanks Patrick
I did not run any of the AIH circuit wires from the PCM to the valley of the engine. It`s tidy and i did not want to clutter it up. and i was hoping their mite be an easy answer so i would not have to add that stuff. Bill
 

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Discussion Starter #4
Also Patrick I had a thought after looking at the diagrams in your reply. What about a relay that you would use for a fuel pump. Do you think it would handle the load of a 470 ohm resistor? Thanks Again
 

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Using a 12V nominal voltage and 470 ohms, the current would be 25.5 mA (.0255 Amps). Power would be 0.31 Watts. So use a resistor rated at least 1/2 watt and relay that can handle that current/power. Cheers!
 

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Discussion Starter #6
Thanks alot Patrick. Sorry it took so long to reply shop is swamped.
 
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