Big Electrical/relay Problems

03YD163 · November 23, 2010

I've been having issues with my 03 Yukon Denali. It randomly will not start, and I mean randomly. About once a week it seemed to be doing it, maybe it was doing it because i was going on trips on the weekend, not sure. So I will get in the car, turn over the ignition, and nothing, no crank, no start, and no flashing pass key light. Beings as though it is a common problem (so i have been told) i replaced the electrical portion of the lock cylinder, and it started flawlessly the next 20 times. That night i went down to a friends house south of town (about a 20 minute drive) and when the game we were watching got over low and behold it took about 10 minutes of me cranking the key over, adjusting the column, and turning the wheels to get it to finally turn over.

I am getting SOOOOO frustrated, i absolutely hate not having a reliable vehicle

-----------------------------------------------------------------------------------------------------------------------------------

SO all this was happening, I had a GM tech I know take a look at it and he replaced the Ignition Relay in the Under the hood fuse box. I also replaced the Starter relay.

The "fix" worked for about ~2 months, didn't have a single issue, then it started again and as I continue driving it it seems to occur more and more often as the weeks progress

I think that the relays are being faulted by some electrical issue? Any thoughts on that?

Another thought of mine would be that the under hood fuse box has some faulty wiring and maybe I should replace that? When it doesn't start I can go "wiggle" the ignition or starter relay and it seems to fix the issue, a majority of the time it will start after that.

I have also found that disconnecting the battery and reconnecting it will often solve the no start/no crank symptoms ( I should note too that both battery terminal bolts have been replaced and it has a brand new battery)

Thanks for any help in advance, this is getting old! I'll try and watch this closely if anyone needs anymore info

ChevyTech77 · November 23, 2010

It could just be something as simple as a battery cable connection issue or a poor ground.

Does the starter even click when this happens?

The tough part is that your diagnosis, and any repair, is just a complete guess unless you can get it to act up and diagnose it while the concern is happening.

03YD163 · November 23, 2010

It could just be something as simple as a battery cable connection issue or a poor ground.

Does the starter even click when this happens?

The tough part is that your diagnosis, and any repair, is just a complete guess unless you can get it to act up and diagnose it while the concern is happening.

Ya and the grounds were my original thought and I checked all grounds, they seem fine.

I have a Tech2 available for use, but it's very complex as im sure many of you know, is there a way to pinpoint the issue using a tech2?

And the starter does not click or anything no, nothing happens, all electrical comes on, but when I turn the key, nothing

ChevyTech77 · November 23, 2010

Ya and the grounds were my original thought and I checked all grounds, they seem fine.

I have a Tech2 available for use, but it's very complex as im sure many of you know, is there a way to pinpoint the issue using a tech2?

And the starter does not click or anything no, nothing happens, all electrical comes on, but when I turn the key, nothing

How did you check the grounds? A visual inspection, other than to make sure that they are there, isn't good enough in a situation like this. A loaded voltage drop test is the only way to fully ensure all electrical circuits and connections have good integrity.

If you have a Tech 2 at your disposal during the event, you'd need to go into the ecm and bcm to verify crank request signals. It's a fairly simple procedure that you should be able to figure out with some basic navigation skills with a Tech 2. Practice up!