Will not stay running?

Hi Jimmy,

It could be a few different things causing this. Yes, the PCM could be the cause, but other things can cause it as well. For example, if the ignition switch is faulty and only supplies a signal for ignition in the start position. An issue with the fuel pump or ignition system can do this as well.

So, here is where we need to start. First, why doesn't the scan tool connect? If you look at the pic below, check pin 16 (highlighted with yellow) for B+ voltage. If that is good, confirm pins 4 and 5 have continuity to ground. Note: If there is no continuity, try it with the key in the on position/engine off.

The last two pics are of the computer data lines. Note Fuse 11 in the interior fuse box which is for the cigarette lighter as well as powering pin 16 on the DLC, needs to be checked (see last pic for location). In addition to checking the fuse, make sure there is power to and from it.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know what you find.

Take care,

Joe

See pics below.

Thank you for taking the time to help. Not sure if it’s been 2 or 3 years since it ran for more than seconds. The first thing I did was new fuel filter, no change. Next checked fuel pressure and it had over 50 PSI. I thought it was good put new fuel pump in anyway. No change. When I took the gas tank out something had been chewing on wires. I think repaired wires and new pump worked fine. No change. Took the key to dealer and had resistance checked. He thought it was okay. I bought a new key and cylinder. No change. Just checked pin 16 has power and 2 good grounds. Can computer be taken out and scanned? Need some codes.

Hi,

As far as checking the PCM, I don't think that can be done outside of the vehicle other than if you have specific equipment.

Did you replace the actual ignition switch or just the lock cylinder? Does the security light stay on constant or flash? If it does, turn the key to on and allow it to sit on for approx 10 minutes to see if the light goes out. If it does, see if it will start then.

Does it seem to only run when the key is in the start position and then stall when you release it to the run position? I ask because power is directed differently in the two positions.

Let me know.

Take care,

Joe

Want to thank you again for your help. Does the ignition switch come with a long orange wire that comes out bottom of steering column, and a place to put key. Security light comes on briefly and then goes out. Starts briefly and stops again and again. When it stops all the gauges bounce back and forth. Act’s like it’s out of gas. Got a new code reader. Power’s up but no communication. Pins to power and 2 grounds good could pin to data port be bad. Should I try to follow purple link wire. Does wire go to BCM or PCM. Tried resetting the computer by removing PCM battery and ign fuses for 20 minutes. I don't like the thought of having it towed to the dealer.

Hi,

One of the wires from the ignition switch is orange. When you have the key in the run position, it sends power to fuses in the IP fuse box. I attached a pic below so you can reference what I am saying.

The purple wire goes to a splice pack under the dash on the left side which ties with the PCM. See pic 2 below.

Let me know.

Joe

See pics below.

Starts for 2 seconds and shuts off. GM service manual mentioned car cranking longer before starting. That’s what mine did before starting and stopping. Could crank sensor be the problem? If I removed sensor would I be able to tell if it was good?

Hi,

The crankshaft position sensor will shut down the spark to the plugs if faulty. Have you checked for spark?

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Also, I'm assuming it doesn't start at all now. Is that correct?

Joe

Runs for two seconds.

Hi,

Could you record it starting so I can see exactly what is happening? If you can, do it from the driver's seat and have the camera on the key when turning.

I want to get a different tech's opinion as well.

Let me know.

Joe

Thanks again for your help. I took the starter out to get at crank sensor. Sensor very hard to get to. Sensor stuck does not want to come out. Might be a couple of days before I get new sensor installed.

Hi,

Here is what I suggest. They rust in place and as you have learned, they get stuck. Take a wire brush and clean as much of the corrosion away from the engine/sensor as possible.

If you have a torch, heat the block around the sensor to cause it to expand, and then try getting it.

If that doesn't work or if you don't have access to a torch, they make a product called freeze-off. It is made by CRC, and you should be able to get it at any parts store. From my experience, it works great. It is a penetrating fluid just like the others, but somehow, it caused the component to contract which will usually break any rust holding it. Just follow the directions on the can.

It's just a thought. Just spray it with some type of penetrating fluid and allow it to sit. Then gently work the sensor back and forth. You don't want it to break off. If it does, it is a new problem to deal with.

Take care and let me know if I Can help.

Take care,

Joe