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Pontiac G6 3.5L v6 wont start

I have a Pontiac G6 3.5L v6 that won’t start. The last couple of days when turning the key I noticed it was taking a little more effort to start so today I got home turned the car off and wanted to really take a listen to what was going on when I started it so I turned the key and it wouldn’t turn on. The lights on the dash came on the ac turned on and the radio works but I get no noise from the engine no clicking or anything. Another thing I noticed is when I would turn the key the speedometer would go all the way to max and then come back down. I tried wiggling the key while turning the key and nothing. I tried starting it in neutral and nothing. I tried jumping it and also nothing. If you have any suggestions or ideas as to what it is or how to proceed I would greatly appreciate your help.

A bad PCM can cause this problem, though you can’t open it to see if it is fried or not. You can get a used one and have it reprogrammed for your car.

Why would you jump straight to the PCM? To me it sounds like a typical starter of battery issue.

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Is there any way I could check if the pcm is the problem?

check the simple things first. The battery, the starter, the starter solenoid and the cables from the battery to the starter and to ground.

Could also be the ignition switch or starter relay.

If you have a voltmeter, check the battery voltage and the voltage at the starter terminals (to starter case) while trying to start.

Battery connections are the first place to begin when you have a “No Crank” situation. Even
if you have a new battery, if the connections are loose, dirty or corroded, you will not be
allowing the full flow of current to pass thru the connections. The connection may be
enough to turn on the lights, but not enough for the huge flow that is needed to operate the
starter. This is where many people say that they know the battery is good….”because the
lights come on”. This is no more a battery test than licking a 9volt battery. It only tells you that there is electricity…not how many volts or the amperage that flows from the battery.
Jump starting may have wiggled the terminal just enough to allow the current to pass and start the engine, but tomorrow you have the same problem.

First remove the cables from the battery and use a wire brush to remove any corrosion and dirt from the battery posts and the cable terminals. There is a tool with a round wire brush for this purpose, found at any auto parts store for less than $10 http://shop.advanceautoparts.com/p/kd-tools-terminal-battery-brush-kdt201/25980576-P?searchTerm=terminal+brush.
Before connecting the cables, apply a coating of di-electric grease to the battery posts this will keep oxygen away from the connection so that it will not corrode as fast.

It is just as important that the other end of the cables also have a clean connection. Remove the negayive cable from the battery again so that you do not short anything out. Follow both cables to their far ends, remove this connection and wire brush the connection and the cable terminal clean and retighten these connections.

If there was work done recently, there may have been an “engine to body” ground that was not installed following the work. These grounds normally run from the rear of the engine to the firewall and are uninsulated and most are a braided wire. If any of these are found unattached…reattach them.
Remember….this is not a “Sherman Tank” don’t over tighten the connections.
Tight…tight………………too tight…broke!!!

Yosemite

So you got a no-crank problem , right? You get none of that rrr rrr rrr sound you normally do when you turn the key from on to start. Excellent advice above. Discount the PCM as the problem until the easy stuff has been done first. When there’s no obvious reason for a no-crank, the most informative test is to measure the voltages at the starter motor during attempted cranking. Both terminals should measure at least 10.5 volts, terminal to starter motor case. You might ask your shop to make that test if everything else proves inconclusive.