2004 Nissan Altima No Start with ECU Relay installed

Hello Danner. I'm a new member and thanks for the cool videos you've posted on youtube. Here's the problem I'm having. My son's 2004 Nissan Altima 2.5L was having issues. First, it wouldn't start one morning. Cranked but wouldn't start. So he checked and changed the cam and crank sensor. Still didn't start. So he changed the spark plugs and it started and ran. Then later on he would start it in the morning and go get gas and it wouldn't start. It would take some time for it to start. So one day we drove it till it got up to normal temp. Pulled over and turned off the engine. Then it happened again. No Start. Waited, then it eventually started. It had a new fuel pump, Cam and Crank sensor(Aftermarket. Maybe the problem), Sparkplugs. MAF Sensor. Then it got worse. It wouldn't even start and the fans just started going on. I removed the ECU Relay and it stopped. I put a jumper wire in the 30 & 87 pins and the car would start and run great. I pinpointed that there is a power ground wire that is triggered from the ECM to the Relay. I even had the ECM rebuilt and the company said that there was only an EFI transistor that needed replacing. I still have the same issue. Here's My question. What triggers the power ground to activate? Can it be the Cam or Crank sensor?

Do the fans turn on still with the key on? This is a default if the ecm is offline. Are you able to communicate with the ecm? If so what are the specific codes?

It's a common mistake, but his name is actually Paul Danner aka scannerdanner.

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Allbrant wrote: What triggers the power ground to activate?

I think simply turning the key to the ON position will activate the ECM relay. Reinstall ECM relay, key on engine off and check for battery voltage at the MAF. Load test a power feed wire at an ignition coil to be sure. A relay click doesn't mean it's good.

www.nicoclub.com/service-manual?fsm=Altima%2F2004%2FEC.pdf

there’s a whole lot of nissans that are effected with the failed ECM relays. Tell tell sign is to watch the check engine light and see if it flickers during crank. If you have the old sensors I’d suggest putting them back in. Especially if the replacements have a wallet with wings.

When I plug in the jumper wire on the 30 & 87 ECU relay the car works normally. With the relay in the fans go on and no communication for codes.

I switched the relay with 3 other relays and same result.

Verify control. I’ve included a diagram if you need it.

What activates the Wite and black wire?

Use test light connected to ground and back probe the black and white wire. Should energize the relay if the wire is good from pcm to relay.

If it doesn't what could cause it not to activate? Bad Crank, cam sensors? Bad ignition switch?

You need to check pins 6 and 14 at the data link connector. Battery unhooked. Should see close to 60 ohms. And if the relay doesn’t activate doing that test before you need to check the wire for an open.