So I have a 2003 g35 coupe and my rear tails don’t come on unless the break pedal is pushed on. I looked on the forums and they say replace the tail lamp fuse in the fuse box behind the battery. I pulled the ecm ignition fuse and taillight fuse and they were both blown. I replaced both of them with 10amp fuses and I turned on the car and it wouldn’t shut off unless I pulled the fuel pump relay and the battery to get the motor to turn off and all the lights on the dash. The same day I ran out of gas because my gas gauge read wrong and didn’t read under 3/4 a tank and when I finally got gas after the whole ordeal I put 15 gallons in the tank and still was ready a little too low. Any idea why my car won’t shut off with the key being in the off position? Or why my fuel gauge isn’t reading right at all? Someone told me it could be a bad fuel pump and ignition relay and I’ve also heard that I need a full ignition switch assembly.

 

I think if the ignition relay is stuck closed that the car will fail to turn off since it's still powering the ECM. I think you can swap it with another relay in the IPDM because there are a couple that are identical, check section PG - Power/Grounding under IPDM for the layout.

Fuel gauge is usually a separate issue, sometimes it's the float, sometimes it's the instrument cluster. Troubleshooting steps in the FSM section DI - Driver Information under Fuel Gauge.

Tail lights troubleshooting is in section LT - Lighting.

Another possibility is some kind of aftermarket remote start or alarm that's failing and not interrupting power when you turn the key off.

 

so I should replace the ignition relay in the ipdm?

 

No you should swap it and another relay and see if the problem persists.

Troubleshoot the problem before throwing random parts at it hoping something will fix.

 

so the car shuts off now without the relay plugged in with they key … I already tried swapping another relay in so the problem kept happening but would turn off and start with the ignition relay out of the car ? Would you say the ipdm needs replacing or can I just run no igntion relay because I drove 45 mins out without it and had 0 issues

 

U sure it was the ignition relay u removed? 🤔

 

positive .. once I removed that relay the car starts and turns off by the key

 

I'd need to see a picture of the IPDM and which relay you unplugged. It definitely should be impossible to start the car with the start relay unplugged.

You can disassemble the IPDM all the way down to a circuit board if you want to give it a thorough inspection.

It's possible that something cooked inside your IPDM, arced out and welded the wires together on the start relay. Does it look burned or corroded on those pins with the relay removed?