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My car cranks but won't start and there is no data from the obd port, though the obd port has battery voltage. I believe I've isolated the problem to the IPDM or the wiring between the IPDM and the ECM, but I'm not sure I'm going about this the right way and would greatly appreciate any suggestions about how to confirm the problem.
After a bunch of stuff checked out fine, I checked for battery voltage to the ECM. I have a 2005 G35x and the EC section of the factory manual says that the red and white wire going to terminal 121 of the ECM should have battery voltage at all times, even with the ignition off. This checks out fine with a multimeter.
There is a pink wire going to terminal 119 of the ECM that is supposed to have battery voltage when the ignition is on. There is a blue wire going to terminal 120 of the ECM that is also supposed to have battery voltage when the ignition is on. However, terminals 119 and 120 are only getting 1.2 volts when the ignition is on. (They show 0 volts when the ignition is off.)
I removed the ECM relay from the IPDM and replaced it with the high beam relay, with the same results. I also tried a jumper across the ecm relay connectors in the IPDM and I got the same result: 1.2 volts going to terminals 119 and 120 when the ignition is on, zero with the ignition off. (I confirmed that 12 volts are going into the IPDM ECM relay connector.)
Also, when I checked the three wires going to the ECM for battery voltage I first disconnected the ECM harness connector from the ECM. I was only checking the wires on the harness connector side while it was disconnected from the ECM. I did not "connect a break-out box and Y-cable adapter between the ECM and ECM harness connector" as recommended in the FSM. I also didn't backprobe the harness while it was connected to the ECM. Is this acceptable? Looking at the diagram in the factory manual it seems that the ECM relay in the IPDM should be putting out 12 volts on those two wires when the ignition is on even if the ECM harness connector is disconnected and it should be possible to read this with a multimeter. Am I right in assuming that 12 volts should be running to the ECM from the IPDM on the pink and blue wires when the ignition is on and it isn't actually necessary for the ECM harness to be connected to test this? (Assuming the multimeter is connected to a good ground.)
Yes you should have power on 119, 120, those come from the ECM relay when the key is in the ON position.
First check IPDM fuse 77, that's what sends power to the ECM relay, actually probe the fuse slot itself to verify there's full time 12vdc. If there's not 12vdc check the fusible link slot E, that sends power to the IPDM fuse 77 along with a bunch of other stuff.
If you have power on fuse 77 verify that you also have power at the ECM relay by removing it and probing the IPDM pins, you should have 12vdc on one of the relay pins that will disappear when you remove fuse 77.
Thank you. Fuse 77 is good and there is power to the fuse slot with the fuse removed. I also have 12v to one of the pins in the ECM relay slot when the relay is removed. With fuse 77 removed there is no power to the ECM relay pins. I jumpered two of the pins in the the ECM relay socket to force power to the ECM. I get the same result as I get with the relay in place: With the ignition on I read 1.2 volts on 119 and 120.
[QUOTE=cleric670;7219757] Yes, there should be current at terminals 119 and 120; these come from the ECM relay when the key is in the ignition position. First, check IPDM fuse 77, which sends current to the ECM relay. In fact, check the fuse slot to check that there are 12 VCCs permanently. If there is no 12 VCC, check the E slot of the fuse link, which sends current to the IPDM fuse 77 along with other components. If fuse 77 has current, check that there is also current in the ECM relay, remove it and check the IPDM pins. There should be 12 VCCs on one of the pins on the relay, which will disappear when fuse 77 is removed.]I have a problem: the fuse is cracking on the ECU on the IPDM, look, you know a lot about it, I wanted to see if you could help me with my problem. Hello, I have a problem, this fuse is breaking, someone could help me with that problem.
