2003 yukon xl multiple trouble codes all at once

[autoxfreak]

hello all new to the forum here. i have a 2003 yukon xl with almost 300,000 miles, 5.3 flex v8. all was good till last week when i got multiple po codes. i have 3 p0449 which is the evap code. 1 pending, 1 confirmed and such, a u1000 code which is for the computer? , and also co226 + 222 codes for speed sensors for both front tires. the truck starts and runs fine but the idiot light is on and i can't get it inspected till i solve this. i have had issues with grounds before. I fixed the ones under driver door on frame, and also one on the front bottom of the engine block. my question is does anyone know if maybe these all share a ground point. i highly doubt everything shit the bed all at once. I did have the battery checked and it's all good. wanted to check here first to see if anyone had something similar happen and might be able to give me a place to start. thanks for any help.

 

[justirv]

hello all new to the forum here. i have a 2003 yukon xl with almost 300,000 miles, 5.3 flex v8. all was good till last week when i got multiple po codes. i have 3 p0449 which is the evap code. 1 pending, 1 confirmed and such, a u1000 code which is for the computer? , and also co226 + 222 codes for speed sensors for both front tires. the truck starts and runs fine but the idiot light is on and i can't get it inspected till i solve this. i have had issues with grounds before. I fixed the ones under driver door on frame, and also one on the front bottom of the engine block. my question is does anyone know if maybe these all share a ground point. i highly doubt everything shit the bed all at once. I did have the battery checked and it's all good. wanted to check here first to see if anyone had something similar happen and might be able to give me a place to start. thanks for any help.

It sounds like you're on the right track, and I agree that it is probably ground or battery related. I'd check for the Big 3 (or 4) grounding upgrade just for confirmation of the various locations. Internal corrosion (in the wire, terminal, or surface) can cause these types of problems. If you have already (fully) replaced these, uou should be good there. Also, I recently had a momentary stumble on another car, loaded up the trouble codes and went into limp mode the rest of the way home... it turned out to be the battery... could be an intermittent internal crack or something (?).

 

[Fless]

I'm spitballin' but will say to try doing a voltage drop test to confirm that the ground and power cables can handle the loads. Maybe the engine-to-body ground from the driver's side head to the body is weak, or another connection is not up to par.

 

[autoxfreak]

ok got a chance to start looking around and found the engine to firewall ground strap was pretty green so started with that first. came out no problem went to put a new one back in and the bolt that holds strap to the block fell out and i can't locate it anywhere. does anyone happen to know the part number of the bolt that holds ground strap to the block???

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I can't help you in identifying that bolt, but other folks will most likely chime in.