QuestionHello,
My 2005 Dodge Grand Caravan intermittently has the check engine light coming on, and then the P0406 code usually occurs, but sometimes, P0403 also occurs with it. Before I change the EGR valve assembly, please tell me how to troubleshoot the wiring for a possible short/open. I checked pins 1 & 2 at the EGR valve for power, and it shows 5VDC on both all the time, regardless of whether the ignition is turned on or off. That's why I suspect a short to power with the signal lead.
Thanks,
Daniel Thessen
AnswerHi Daniel,
The '05 wiring diagrams show there to to be three wires at the 3.3L egr solenoid: a sensor ground, a 5V supply, and a variable voltage that results from a tap on a variable resistance between the 5v and the ground. I assume you have the 3.3L engine.
But you are correct it would appear to me that the 5v supply which comes from the pcm should not be present when the key is off. The number 2 34-wire plug at the PCM shows the wires to be on pins 29 (pink/yellow 5v), 22 (dark blue/light green signal) and 27 (dark blue/dark green sensor ground). You could pull that plug and check for voltage on pin 29 of the pin side and the socket side to see if you have a short to 5v on the harness. I would believe by the 5v supply wire's code F855 that it would not be 'hot' unless the ignition were on. So either the supply wire is shorted, the signal wire is shorted, or the pcm might be powered regardless of the position of the key.
I will be interested to know what you determine.
Roland
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