Wiring issue - Crank, No Start

[BoostedC230]

Hello everyone, I'm new here. I've got an interesting issue here. I got ahold of an 04 gmc yukon that had been sitting for four years with no engine in it. I got an engine went through it and got it ready to go. I threw it in but all it does is crank no start. Fuel pump primes, I have rail pressure. I also have spark. I have a relay marked as " IGN 1 " that clicks a lot when turned to position 2. To see if the relay was bad I used two new relays that I had in its place. They both clicked like crazy. I have checked both grounds behind the intake. Those grounds are good, I've also checked the two block grounds and they're also good. I've unclipped the injectors and checked the power wire and my test light flickers the entire time. ( Not the grounding wire to the ecu ) the red power wires. In the fuse block there is an ecu and tcm fuse which never have power. I'm not great at electrical diagnosis. I've been trying to improve with this project. I'd like to see if someone could assist me as I feel like an outside person looking in would be very helpful. I appreciate you taking the time to read my write up.

 

[rockola1971]

Hello everyone, I'm new here. I've got an interesting issue here. I got ahold of an 04 gmc yukon that had been sitting for four years with no engine in it. I got an engine went through it and got it ready to go. I threw it in but all it does is crank no start. Fuel pump primes, I have rail pressure. I also have spark. I have a relay marked as " IGN 1 " that clicks a lot when turned to position 2. To see if the relay was bad I used two new relays that I had in its place. They both clicked like crazy. I have checked both grounds behind the intake. Those grounds are good, I've also checked the two block grounds and they're also good. I've unclipped the injectors and checked the power wire and my test light flickers the entire time. ( Not the grounding wire to the ecu ) the red power wires. In the fuse block there is an ecu and tcm fuse which never have power. I'm not great at electrical diagnosis. I've been trying to improve with this project. I'd like to see if someone could assist me as I feel like an outside person looking in would be very helpful. I appreciate you taking the time to read my write up.

You're in luck....former aviation electrician USN and been an electronic tech and electrician for decades now. Need to know what trim package (SLE, SLT) and 2wd/4wd/AWD and what are the 2 fuses exact name in the fuse box cover table? (ECU1? or ?) Yours has a ECU and TCM in 2004 instead of just a PCM (which has both the ECU and TCM internally)?
Once I get trim and chassis along with fuse names I can pull up the correct electrical diagrams and I work with you from there on checks to see where your voltage stop is.

My preliminary guess is that you have corrosion underneath your fuse box. The green crusties so it wouldnt hurt to pull that up and have a look. Lots of youtube vids on how to do.

 

[dadwagon95]