Hi so the problem is my 2005 G35 6 speed won't start, it cranks, but there is no power to the fuel pump, no spark and no power to the ecu. When I turn it to the on position the fans and lights come on but I cannot check for error codes as my obd 2 just says error. From what I could gather this sounds like an IPDM problem, I purchased a used one off ebay but I still have the same issue, so I am not sure if its a different problem or another bad IPDM. The background is I have had the car for about 7 years now, no real problems. I recently purchased a new car, so this one sat for about a week and a half as I was getting it ready to sell it, it did also rain quite a bit in that time. I went to start it but the battery was dead, so I charged that and when I hooked it back up the alarm started going off, so I stopped that and tried to start it but all it would do is crank. I ended up getting it to a mechanic, they had it for a while but still couldn't get it to run. They saw the IPDM was very corroded so they tried to clean it but still wouldn't start. So I figured it might just be a bad IPDM, I got it home ordered one tired it and nothing. So I am now at a loss if I should try a different IPDM or if its possible there's just a broken or corroded wire somewhere, I have included all the info I could think of and I am hopeful someone can point me in the right direction. Thank you.

 

Is it possible that a ground wire broke and/or corroded somewhere? I had a ground break on me, and it wouldn't start. it was the one that attaches to the front part of the engine, seems common. But, there are several gorunds, like the big one that goes to the chassis, and if corroded it might be part of this issue.

It also could be a short, if you plug it and and the alarm goes off.....not good.

Ah, and also check all your fuses, you could have blown one that stopping the car from starting.

 

Yeah I am worried it is just some wire some where that I can't see. Ok thanks I will check that one. I think the only reason the alarm went off was because it was set before the battery died, so after it getting power and the hood being up it would probably go off, but I could be wrong. Yes I forgot to mention, I checked all the fuses and the all seem fine.

 

Check your fusible link holder, all that rain probably blew one of the primary fuses especially if it killed an IPDM.

This also explains why so much stuff is still deenergized.

 

They all look good, I double checked the fuses as well, they seem to be good as well. I'm not even sure if the IPDM was the problem at this point, as the replacement one didn't seem to cause any change, unless it was fried as well.

 

This is starting to sound like the ECU died. Are you able to pull it out and see if water got into it as well? It's on the passenger side footwell behind a removable carpeted cover.

 

The mechanic I had it at, had a look and there was no water, it all seemed fine. However the ECU was getting no power, and looking back at their notes it looks like it says there was no power going to the ECU from the IPDM

 

That's why I was thinking fusible link, one of those 15 amp fuses on the fusible link powers the ECM. It's full time powered even with the car turned off. However there's a few power sources that ALL have to turn on for the ECM to be talking on the diagnostic port.

Look on the back of the ECM, red wire white stripe. That's the full time power from the battery.

White wire/blue stripe is power from the key when the ignition is turned to ON.

Pink wire and blue wire are the power supply circuits from the IPDM ECM relay, powered when the key is ON.

 

He can just jumper the socket to see if power appears, yes? Then that will determine if the relay is bad.

 

I'm not 100% sure but I seem to remember that relay was normally CLOSED and the ECM would signal to OPEN the relay. Something about if it ever failed it would stay in the closed position so the car would continue to run.

Don't quote me on that though, been a while since I looked into it. I would just test for power at the ECM to see if it's going through the relay, only takes like a minute to pull the glove box to access the back of the ECM harness.

 

Thank you, the red wire has power, however I cannot tell which white wire with a blue stripe to check or should they all have power? And is that the same with the pink and blue wire?

 

I had a better look, it looks like the white wire with a blue stripe is getting power. But the pink and blue ones are not, supposing I was looking at the correct ones. I also tried to swap around the relays to be safe but it didn't do anything

 

Check fuse 77 in the IPDM, the pink and blue wires is the power from the ECM relay to the ECM.

 

The fuse is good, I swapped it just to be safe and checked for power, it is getting it. But there is no power to wire 18, the pink one, I checked both on the inside of the panel and on the outside of the connector. I also checked the relay, it has power when the battery is connected but when turned to on there is no change. Is there anything else it needs before it can send power out or should it just have power?

 

The line side of the relay for both the coil and the contact will have power (part coming from the fuse).

The load side of the coil is actually a ground wire essentially, the ECM closes the ground which then energizes the coil (spiral thing on the relay picture) it's just an electromagnet that pulls the contact (the not connected bar on the relay picture) down to make contact across the line and load points.

I would try a new ECM relay.