i have a 04 gmc yukon ive had it about a year. transmission pouring out tranny fluid. so i let it set. pulled tranny out and had rebuilt. get it back and put it in. i go to crank it and nothing security light on dash is lit and solid. so i go to obd2 port and hook scanner up. it lights up but wont communicate with truck. i pulled everyone of the fuses under hood and driver side fuse box. with hot battery and my other truck hooked up to it i still got nothing. bypassed starter relay just to see if getting fire to starter. starter did nothing pulled starter and check on ground and its bad. put new one on and still get nothing via the key. go to relay and jump from there and starter engaged and got motor to turn over. ive tried the relearn procedure still nothing. i flat out dont understand! what is the deal ??
04 yukon no crank no start no nothing
- Thread starter Waco kidd
- Start date
Mooseman
Moderator
Welcome to the Nation.
Back to the basics; is there power getting to the PCM? Are the grounds to it good? I just helped someone with a similar problem where one bad ground wire out of four to the PCM was to blame. Did you check the ignition switch for power output to wires on ignition and crank? Check my signature for the link to the manuals for schematics.
Next would be to check for communications on the CANBUS. Is other stuff working like the windows and cluster? Are you able to scan for other modules like the BCM and door modules? Again using the schematics, pull the comb out of the main splice pack and jumper only the OBD port to the PCM and see if you can communicate with it then. There might be a bad module killing the CANBUS.
Back to the basics; is there power getting to the PCM? Are the grounds to it good? I just helped someone with a similar problem where one bad ground wire out of four to the PCM was to blame. Did you check the ignition switch for power output to wires on ignition and crank? Check my signature for the link to the manuals for schematics.
Next would be to check for communications on the CANBUS. Is other stuff working like the windows and cluster? Are you able to scan for other modules like the BCM and door modules? Again using the schematics, pull the comb out of the main splice pack and jumper only the OBD port to the PCM and see if you can communicate with it then. There might be a bad module killing the CANBUS.
windows do work but only on acc. all lights come on when key is turned to start or the on position . turn to acc all lights get brighter. turn to off all lights on. i have to keep battery disconnected. let me ask this. truck did not come with factory key with chip in it, this has to be a copy w/no chip. with battgery being dead could pcm loose everything and when i put that key thats a copy in pcm didn't reconize it and shut truck down and put it into anti theift mode? i will say this i did hear the fuel pump cut on for a second and haven't herd it since. im fixing to go out there and see what i can do on what you sent me last night. ill check back in about noon central time. thank you for your time mooseman greatly appreciated!
Mooseman
Moderator
If I'm not mistaken, these trucks also use the chipless PassLock system. It would not lose the learned security if the battery is disconnected.
Check the actual voltage output of the ignition switch, not just what stuff is doing while turning it. If windows stop working when turned to RUN, I would suspect a bad ignition switch. If stuff is staying on with the key OFF and the driver door is opened to kill RAP, I would also suspect a bad switch or it's gear not indexed properly.
Check the actual voltage output of the ignition switch, not just what stuff is doing while turning it. If windows stop working when turned to RUN, I would suspect a bad ignition switch. If stuff is staying on with the key OFF and the driver door is opened to kill RAP, I would also suspect a bad switch or it's gear not indexed properly.