Help me diagnose no-start on my 99 Suburban

[racered]

Factory alarm will not interrupt starter function.
Does your starter turn the motor?

 

[pronstar]

I know this was a long thread...

The truck ran and started great.

Then the key had no effect at all, no sound, no click.

Then it suddenly fired right up like nothing ever happened.

This tells me:
Battery is good
Starter is good (when it wants to be)
Wiring is good

So I'm down to an intermittent electrical issue that's affecting the starter, methinks.
Either the starter, or the key/ignition.

New AC Delco starter is going in. Was gonna go with the reco on the first page, but wouldn't have gotten it until next week and I want to knock this out today.

Stay tuned...

 

[rvrrun]

Based on what you just posted, if the headlights don't dim when turning the key, I would guess neutral safety or starter switch. Try messing with the shifter when it won't start, or shifting to neutral, and see if that helps.

 

[pronstar]

But if the radio did shut off, doesn't that indicate the switch is ok?

Neutral had no effect.

 

[SBMech]

But if the radio did shut off, doesn't that indicate the switch is ok?

Neutral had no effect.

BCM disables unneeded circuits to supply max amperage for cranking...did I not already say that?

The switch is not just a 2 wire contact for the starter, the load part can fail and not activate the starter relay, but the other circuit that tells the BCM and ECU you are cranking can still work.

Welcome to modern (at this stage is ancient) electronics...

If it needs a switch you'll see, it's a giant assembly with no less than 10 wires, has all sorts of goodies built into it, and a giant bulkhead connector that screws into place in the main fuse board.

 

[pronstar]

The problem with diagnosing the switch right now, methinks, is that it's working perfectly [emoji53]

 

[pronstar]

Old starter out.
Wiring looked good, solid and the ends weren't corroded at all.

New starter works LOL
Sounds like it spins faster, but truck always fired right up so i never really heard it crank for extended periods.

Hopefully it fixes the issue.
Nothing like throwing parts at a problem LOL

I don't mind replacing it tho, maybe get a little peace of mind from doing something, versus doing nothing (since it was working great) and hoping it fixes itself.

 

[rrrr]

.

Starters quit working, mysterious wiring faults and other stuff not so much.

It's nice when the simple fix works.

 

[Kachina26]

But that defect wouldn't suddenly surface 18 years after the car was built. There are a bunch of "out there" guesses in this thread.

I'll go with the most likely problem based on the OP's statements and the behavior of the vehicle.

The starter.

Actually, yes it can.