Poor power connections may be behind finicky Pontiac G5

by Jim KerrBackyard Mechanic . Jan 11 2019

Question: I have a 2007 Pontiac G5, 2.2 litre. Lately, I have been having trouble with the car after it has been sitting overnight. If I go out to start the car sometimes on colder or damp nights, it does not want to engage to start, but if you keep trying it will eventually start. Also, at the same time, the anti-theft deterrent light will come on and the gauges on the car will go out of whack and the info-centre screen will show low fuel and power steering, etc. If you let the car run for five to 10 minutes or drive it that way, if you shut it off and restart it, it will clear itself and go back to normal.

When this occurs in the morning, there seems to be a bit of a drag on the engine or transmission. I had it looked at by a General Motors dealership, they checked the BCM and said it was OK and they checked the battery. They put on a new circuit panel and said the old one was corroded and put a new TCM on the transmission. This did not improve the car at all.


— Edward


Answer: My first thought was the anti-theft system was acting up, and it sounds like the dealership had the same thought when they checked the BCM, which controls the anti-theft system, but after looking at the information, I suspect a poor power or ground connection.

The action of the gauges and warning lights indicate either a loss of communication between the instrument cluster and other computers or a poor power or ground connection. The other symptom, the drag on the engine or transmission, could actually be the transmission starting in a higher gear. If the transmission loses power or ground connections, it defaults to starting in a higher gear, so this would confirm my suspicions. The big problem is finding where the poor ground or power connections are located.

Because you have a problem with the starter motor not cranking the engine first thing in the morning, I suspect the problem is likely between the engine and the battery. It is usually loose or corroded ground connections that cause the most problems and cold or damp conditions make it worse. Clean and tighten all ground connections at the battery, body and engine. You may also want to run a separate ground wire from the engine to the battery. I suspect this will correct your vehicle problems.


Question: I have a 2012 GMC pickup with the 5.3L engine. It runs fine on the highway, but at idle, it seems to miss on one cylinder and there is a ticking noise from the valve cover. Spark plugs and wires have been changed. The engine has the cylinder cut-out feature and I have heard that can be a problem. What do you think?

— Robert


Answer: I have seen several engines where one of the lifters becomes stuck or gummy and does not open the valves properly on these engines. Regular oil and filter changes and maintaining the crankcase ventilation system will help prevent these problems, but once they occur, it is more difficult. You can try running an aftermarket oil additive designed to clean gum deposits for a few hundred kilometres and then change the oil a couple times in the next thousand kilometres in an attempt to clean the internal parts of the lifters and cylinder deactivation system.

If that doesn’t work, the next solution is to replace the lifter. It is possible that the solenoid that controls the lifter is sticking, so have this checked with a scan tool before replacing the lifter. Some mechanics will change all the lifters, but they are quite expensive, so others will change only the ones they think are faulty. Consider the cost of labour versus the cost of the lifters when deciding to change just one or all of the lifters.