Help! My G37S Convertible is brain damaged!

[rpar372]

Recently I installed an aftermarket Carplay retrofit kit into my 2011 G37S Convertible. I've successfully done a couple of these before, however, this time I stupidly forgot to disconnect the battery. I now have a car that does not start and indeed hardly responds at all. The radiator fans turn on full blast as does the headlights. The engine won't turn over at all though. Initially I thought I might have fried the BCM so I removed it and sent it to G7 for repair. I got the unit back and I'm getting the same behavior.

My next attempt will be sending in the ECU. Since it's my understanding that the ECU controls the radiator fans, I suspect the ECU may be the culprit. I did check all of the fuses in all 3 fuse boxes and they seem to be ok.

Anyone have any insight into this? Any info would be appreciated. Thanks!

[VStar650CL]

Check the ECM fuse in the IPDM, I bet it's blown. The fans and the no-crank mean the ECM is incommunicado.

[VStar650CL]

[rpar372]

I pulled the fuse again and checked with a multimeter. Fuse is confirmed good.

[VStar650CL]

Might be a bad IPDM then, or a bad ECM. To check, put a test lamp on IPDM pins 49 and 53 with the ignition on, they should both light up. If they do, the ECM is bad. If they don't, hook the test gator to 12V instead of ground and probe pin 69. It should light up. If so the ECM is bad, if not the IPDM is bad.

[rpar372]

I overnighted the ECM to G7 for repair. I didn't get a chance to test via your procedure but I assume they will test it when they receive it. I don't look forward to replacing the IPDM if that turns out to be the culprit. It looks like a mess to replace but I haven't really looked into the details. Hopefully G7 can just repair the ECM and I can get back on the road.

I'll update when I get the unit back. Thanks for the suggestions!

If anyone else has anything to check, I'm all ears.

[VStar650CL]

The IPDM's are actually easy, they're plug-and-play. Infiniti just put them in a bad spot on the G's. Once you get at it, it's a matter of unplugging and plugging connectors.

[rpar372]

Well, I got the ECM back from G7. There was not a description of what repair they performed so I tend to think the didn't do anything. I installed it back into the vehicle, and nothing. Same behavior. Connect the battery and the radiator fans come on full blast as do the headlights.

I replaced the IPDM with the same part number (acquired via eBay). Same behavior.

Before I have this towed 40 miles to a dealer and drop several thousand $$$...does anyone have any other ideas?

[VStar650CL]

The IPDM switching on the lights and fans means one of two things, either the ECM can't talk or the IPDM can't listen. Did you do the tests I suggested? What was the result?

[rpar372]

I had 12v on 53 but not 49. Also 69 did not go to ground.

I towed the thing to the dealer yesterday. I'm at a loss and so far, so are they. I'll report the results back.

[VStar650CL]

Pin 49 is the main supply to the ECM, and it should be internally connected to 53. Having juice on one and not the other means your IPDM has a problem.

[rpar372]

Update. It turned out to be the AC control module. The dealer wouldn't consent to use an ebay one that I supplied so I ended up overpaying through the nose for it. Sick to my stomach and turned off to the brand because of the dealer price gouging. I'll never buy another Infiniti as a result. Live and learn.

[VStar650CL]

If that's the case, you had the "piggy bank" problem. The Maximas back in that era had the same issue, there was a programming slot in the HVAC Controller which faced directly upward and lined up with the gap between the display and the dash ledge. Pennies or dimes left on the ledge in front of the display could fall through and go straight into the slot. If you were lucky a nickel or quarter (too big) would block it, but if you were unlucky a penny or dime could get inside the unit and short everything, often smoking up the unit and sometimes killing the whole CANbus. I'm a Nissan tech and wasn't aware the G's suffered from the same design error, so I'll add that to the knowledge base. Nissan's fix for the problem was silly-simple, new units come with tape over the "piggy bank" slot.