2004 Dodge Grand Caravan SE 3.3L no spark no injection pulse

Car question:

My Grand Caravan SE suddenly died while driving and phoning around, automotive garages are asking too much to have it fixed. I am now checking it and found it has no spark and no injector pulse. When I hooked up my code reader, got this fault code:

P0685 - TCM Power Relay Control Circuit Open

I checked all the fuses at the engine compartment and everything looked OK. Not sure how to proceed after this code, can you help?

ATS Adviser:

This code shows that the wiring between the IPDM (integrated power module) and PCM (power train module) is not connected or an open circuit. You need a wiring diagram in order to see the wiring circuit. When you do, check the IPDM pin 3C4 and PCM pin 28 for 12 volt presence at key on engine off (KOEO). You won't missed it because it has brown white color wire. This wire also feeds the 12 volts supply to all the 6 injectors and ignition coil at pin 2 of the coil harness. This is the main reason you have no spark and no injector pulse.

If this brown white wire is not powered at KOEO, there is a possibility that any of these 3 components are not working: IPDM, PCM and the wirings in between them. To troubleshoot this, find the location of the automatic shut down (ASD) relay from the IPDM module. Then pull out the relay and see the numberings at the back of the relay like 86, 87, 85 and 30. From there you will know which prong holes to test with your voltmeter at IPDM.

When testing the 12 volt supply, please check the following:

1.) The 12 volt power supply at the pin 86 and 87 of the ASD relay plugin at KOEO. If none and you have verified that the 15 amp fuse is OK, then the IPDM could be defective.

2.) At KOEO, measure the ground signal at pin 16C3 with ASD plugin or pin 85 with ASD relay removed. This is the ground wire signal from the PCM and a reading no higher than 0.250 volt. If there is any voltage higher than this, the PCM is defective. If the PCM needs replacement, you need it programmed by the dealer.

3.) There is common fix for this code which is usually a corroded wiring under the IPDM module. It is notorious for being rusted and if you shine a flash light, you might find the green stuff building up at the connections. You can also wiggle it and see if it will start while wiggling the wires.

Check this approximate 2004 Dodge Grand Caravan power supply wirings below:



2004 Dodge Grand Caravan SE 3.3L Wirings



You can get a FREE wiring diagram from most parts stores if you ask for it while buying parts or get it FREE online 24/7 when you join ATS.



Final FIX:

After I dug deeper under the IPDM, I found the brown white wire broke off. Thanks for your quick reply!

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