At first I thought I had a Passlock issue but my security light does not flash. Basically when my car does not start the only lights that are on are the Oil, Battery and Security lights. The security light remains solid - it does not flash. If I leave the key in the ON position for approx 1 minute the Service Engine Soon light comes on and I am able to start it. Very strange. I just had the fuel filter/pump replaced last week - didn't help.

I also realised that the only time I have a problem is mid-day. And this issue only started when the weather warmed up (RI). The car starts without fail at night and early in the morning. Any other time I have to leave the key in the ON position and hope the engine light comes on. Sometimes it still has trouble starting but eventually I get it.

Anyone have a solution for hot weather no-start? I think I narrowed it down to the PCM, fuel relay or ignition switch. Going back to my mechanic tonight to discuss these.

I have also had issues with dash lights recently... Low Tire Pressure, Trac Off, Cruise and Change Oil Lights all come on randomly. Also my driver side window stopped working and the fan switch only works on high.

I would say, most likley something going on with your PCM, or bad connections to it. Check all the connections to the PCM. Get a scanner on it if you have one and see what its doing when its not starting, can you communicate with the PCM it this point?

Update:

Mechanic worked on it for 2 days last week and contacted GM. Eventually narrowed it down to the ECM/PCM. Waiting for the replacement to come in...should be today. I'll post an update on the results. He agreed to replace it for free because I already paid for a new fuel pump/filter and the problem did not go away.

Tried to use it over the weekend... it has become much worse. Extremely sluggish - takes forever to change gears. All the gauges and radio do not work when the engine is running (sometimes they come on if the engine is left running for a few minutes). This is all assuming I can even get it started... it barely starts even at night now because its over 80-90 degrees outside.

We'll see...

Final Update (I hope):

Mechanic pulled out the dash and checked out the ignition while he was waiting for the new ECM to arrive. There were some corroded contacts. Same for the ECM. He fixed and cleaned everything up and it starts perfectly now no matter how hot it is.

Great to hear it fixed, and thanks for coming back on to post your solution.