Help!! No Clue what to check.

I've been driving my 2003 SLT for about 2 years and aside from a couple if annoying electrical problems, the old girl has run beautifully.

The 5.3 has about 150K on it and is still as quiet and smooth as a V-8 can possibly be. Still purrs like a kitten and the synthetic oil is always golden and clean even after over 4500 miles on each oil change.

Couldn't be happier with the Vortec.

Great power, torque and overall smoothness and im sure most of you would agree that this is one awesome engine.

...... But today out of nowhere something happened.

I came to an intersection rolling to a red light at about 5-10 mph when the engine just turned off. The electrical system is still working, but now when I turn the ignition..... nothing.

The engine doesn't crank and doesn't make any effort to try to fire up.

I've checked most of the fuses and only visually checked for any bad connections or loose wires. I really am a greenhorn when it comes to computerized cars with fuel injection. (The carborated V-8s were a little less complicated. I could always get my 350 running in the '76 Blazer and the. 345 in the old Scout was even easier still.

So what I'm saying is....... I am absolutely clueless about what to do with the Yukon.

What are the most common symptoms for this problem? What are the vital things I need to check?

And since I couldn't find the voltage regulator, I figured I best get help from some of you brilliant GM wizards.

Thanx in advance

Codes?

There’s no external voltage regulator, so you won’t find that poking under the hood.
When you say it doesn’t crank and doesn’t make any effort to fire up, just. Cause these words sometimes different things to different people, what happens when you turn the key to start? A click or no click? I whhr whhr whhr but no vroom? Nothing at all?
Check the mega fuse and the grounds to include the one small wire that comes out of the harness behind the passenger’s side head.

In my 1997 Yukon (rest in peace), I had a somewhat similar occurrence, and it turned out that my ignition key switch failed. Once the switch was replaced, the problem did not occur again.

Perhaps, you have a similar malfunction. Just guessing, of course.

I would begin with the basics, have you checked your battery? how old is it? have you checked and cleaned the terminals? checked and cleaned the grounds? even though you have gauges/lights it could still be a bad battery or ground.

Mine did the same thing a few years ago. Once, I was driving and came to a stop sign, and just like that, the engine died completely. I had to pull to the curb and start her up again. It did this a few times intermittently, so I brought her to the shop. They changed the ignition switch and the problem went away ever since.

GSDunk said:

I've been driving my 2003 SLT for about 2 years and aside from a couple if annoying electrical problems, the old girl has run beautifully.

The 5.3 has about 150K on it and is still as quiet and smooth as a V-8 can possibly be. Still purrs like a kitten and the synthetic oil is always golden and clean even after over 4500 miles on each oil change.

Couldn't be happier with the Vortec.

Great power, torque and overall smoothness and im sure most of you would agree that this is one awesome engine.

...... But today out of nowhere something happened.

I came to an intersection rolling to a red light at about 5-10 mph when the engine just turned off. The electrical system is still working, but now when I turn the ignition..... nothing.

The engine doesn't crank and doesn't make any effort to try to fire up.

I've checked most of the fuses and only visually checked for any bad connections or loose wires. I really am a greenhorn when it comes to computerized cars with fuel injection. (The carborated V-8s were a little less complicated. I could always get my 350 running in the '76 Blazer and the. 345 in the old Scout was even easier still.

So what I'm saying is....... I am absolutely clueless about what to do with the Yukon.

What are the most common symptoms for this problem? What are the vital things I need to check?

And since I couldn't find the voltage regulator, I figured I best get help from some of you brilliant GM wizards.

Thanx in advance

Click to expand...

Doubeleive said:

I would begin with the basics, have you checked your battery? how old is it? have you checked and cleaned the terminals? checked and cleaned the grounds? even though you have gauges/lights it could still be a bad battery or ground.

Click to expand...

This^^^ terminals on the battery loosen up, corrode, even fall off the battery.

go to any parts store and ask for a code reader. they can tell you what parts to buy if codes say so.

Check the starter connections, those sometimes get loose. That happened to me several weeks ago, one connection was completely loose. Tightened it up and has been running with no more issues.