Car Talk: A simple test can help identify a GMC truck that won’t start | Lifestyles

Dear Car Talk:

I have a 2003 GMC Sierra.

Sometimes it won’t play or start. There is nothing. All the usual components have been checked — battery, starter, alternator, fuse — and I am told all are good.

I twisted the exhaust pipe and bent it and started it after that, I have had this problem repeatedly. Could it be a bent exhaust pipe? — James

I don’t think so, James. I listed 1,000 possible objects, and the curved back pipe came in at about number 997, just above an intervention from visiting aliens from Pluto.

If you created an exhaust pipe and completely blocked the flow of exhaust, that could stop the truck from running.

It would be like sticking a potato in the tail pipe. If the electric smoke cannot come out, then gasoline and fresh air have no chance to enter, and the car will not work.

But even then, the truck would still crash. And you say that when this happens, you don’t even defend it. You also say this problem comes on and off, and I doubt the exhaust pipe twists and turns while you are inside watching “Young Sheldon.

Let’s assume that your mechanic checked all the battery and alternator connections. Those can deteriorate over 20 years or loosen and cause the truck to not start at some point.

If all connections are solid, the next thing I will try is the Neutral Safety Switch. That is the switch that prevents your truck from starting unless the shifter is in Park or Neutral. When that switch fails, it can prevent the truck from crashing even when the shifter is in Drive or Neutral.

One simple (though not conclusive) test is this: When the truck fails to start, put it in Neutral instead of Park and try again. If it still doesn’t start, leave it in Neutral and turn the throttle position key with your left hand while touching the shifter to Reverse and then Drive with your right hand.

If it does start, that adds weight to the Neutral Safety Switch theory. And if that doesn’t fix it, you can try replacing the starter. Beginners often fail. Random failures are a common sign of a failed startup. When your technician tested it, it probably worked fine. But that doesn’t mean it works well 100% of the time.

If none of those suggestions work, James, reply, and I’ll give you numbers 4-10 on my list. Good luck.

– Do you have a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Automotive Discussion website at www.cartalk.com.