QuestionRoland,
I already talked to you about this 2005 Dodge Grand Caravan regarding the EGR valve and the P0406 code. The reason I didn't find the wire coloration the way you described is because I was looking at the BCM, not the PCM! Please describe for me where the PCM is. I went to the Dodge website and found a useful list of diagrams, but when it shows the PCM location, it's for a 2.4L engine, not my 3.3L engine. On the picture, it shows the PCM at the rear of the engine (left side of the engine compartment), but I can't see it anywhere; the only thing I see coming out of the rear of the engine is the transmission. Please tell me the location.
Thank you. Daniel
QUESTION: Hello,
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
ANSWER: Hi 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
PS Please 'rate' my answer, and consider a 'yes' where the question about a nomination to be 'volunteer of the month' is asked. Thank you.
---------- FOLLOW-UP ----------
QUESTION: Roland,
Sorry, I misspoke the first time. The voltage at the EGR valve is present only when the ignition is turned on. But when it is on, 5VDC is present on both pins 1 & 2; pins 3 & 4 are grounds. From what I've read about it, only pin 2 should have 5VDC present; pin 1 should be zero if the EGR valve plug is off and variable when it is installed. Is this correct?
Also, which PCM plug is #2, the second one from the top, or the second one from the bottom? There are five plugs on it.
Thanks again,
Daniel
ANSWER: Hi Daniel,
Yes, that pin 1 wire is the signal wire and it will only show a varying voltage if the egr valve is plugged in because it depends upon their being a 5 volt supply on pin 2. I am not certain what the voltage might be on the signal input of the signal circuit at the pcm (pin 1 while unplugged) so when I say it will only show voltage I mean it could be a fraction of a volt as the 'open' input of the signal measuring circuit. But clearly 5v would be a short between the supply and the signal wires. The numbering of the pcm plug is as you described it as far as I can tell. Just verify the wire colors on the specific pins that I mentioned. Thanks for mentioning that there are other wires which didn't show up on the wiring diagram page for the egr signal circuit. I thought it might only have the three wires but now see there are 5.
Roland
Please 'rate' my answer, for which I would be most appreciative.
---------- FOLLOW-UP ----------
QUESTION: Roland,
Sorry to bother you again, but none of the wire colors and plug numbers you mentioned match what this vehicle actually has. However, plug #3 does have a purple wire with a green stripe on pin 22, and there are two wires spliced to that wire, and they go to an after-market remote keyless entry module.
(We just bought this van, so I'm not sure what happened to the original remote keyless entry system. The installation of this system appears to be semi-professional, not professional.) I guess it could be that P3-22 is actually a door-unlock circuit.
Do you know where I can find a wiring diagram for this van? If I have to buy it, that would be okay, as I want to figure out that remote keyless entry system too: VIN # 1D4GP24RX5B226981.
Thanks!
Daniel Thessen
AnswerHi Daniel,
I am uncertain because it depends upon whether your van has the separate pcm and tcm or instead the 'ngc' (a combined engine and trans controller in a single package). If the former then the pcm is located on the left inner fender directly adjacent to the battery. If the latter, then it is hidden in the area underneath the left headlamp and you access it by turning the wheels full left, lift the front end on that side, remove the panel just in front and to the right of the left front wheel called the inner splash shield, and behind that panel you will find a cavity where the ngc unit is located. So look first for the pcm, and if not found then look for the ngc.
I suspect it is the ngc because the specific engine wiring diagrams shows 4 separate 34-pin plugs whose wiring I described, while the old style pcm only has 2 40-pin plugs.
Roland
PS Thanks for generous rating and nomination.
