I need help diagnosing a problem

I have a 2001 GMC Yukon and I have a problem. When I turn the key, nothing happens. No noise whatsoever. All the power locks, lights, power windows are strong. I tried jumping it and that didn’t work. I figured it might be the ignition switch until I took the bottom of the column off and noticed the shift interlock solenoid was just laying there. Not connected. Can anyone give me an idea of what I’m dealing with? Thank you.

Check the start relay in the fuse box underhood. Swap it with its neighbor, try and start. Make sure the socket terminals are all there and not badly corroded.

If it doesn’t start, check the ground, supply and then the signal when the key is turned. You will need a volt-ohm meter for this and the knowledge how to use it.

Check the resistance of the negative battery cable to the engine block. Check the positive cable to the starter terminal for 12V.

I’ll assume you can recognize what is wrong when you see it. If not, post back with what you find and we’ll go from there.

No experience with Yukon, but have investigated this problem extensively on my Corolla. Besides ignition switch and start relay, faulty clutch safety switch (if manual) or neutral safety switch (if automatic) are also possibilities. With key in start the “s” terminal (thinner wire) at the starter should measure at least 10.5 volts. As should the other thicker wire’s terminal. Ask your shop to do this check for you. If it tests ok, and engine doesn’t crank, faulty starter motor is another possibility. A seized engine could cause this, but usually you’d hear some sort of click sound with key in “start”, so doubting that possibility.

I’m guessing 10.5 volt test above fails, and clutch or neutral safety switch is the problem. If feeling lucky … If automatic, try cranking engine in neutral rather than park. Or jiggle transmission selector slightly while cranking. After that, ignition switch. Under-dash start relay possible, but isn’t a common failure item. Discharged battery and problematic battery, ground, and wiring harness connections possible as well, so first step is to make sure batteryfully charged and clean battery post connections.

dealing with this issue on a 2010 right now, so I gotta ask: Is the shift selector lit up? When you shift gears, does the selector move with you?
Mine has a bad fuse box causing the transmission control module to go offline- causing this same symptom at times, and other times causing a no shift.

beyond that- check battery cables for cleanliness and tightness.


If this has those lousy side terminal battery cables, I would start by removing and cleaning them and tightening them.

Sometimes they will let enough juice through for everything but the starter.