Cadillac Repair: 96 Cadillac Deville wont start on occasion, ignition forensic expert witness, forensic locksmith


Question
My vehicle has been randomly not starting for over a year now. It can go a week or 2 starting fine, then all the sudden just not start... For the most part when it doesn't start right away it only takes a few turns. Sometimes it wont turn over at all, other times it will start to turn over then just stop. I did the dim light test at night (starting the car with the lights on and seeing if they dimmed, they didn't) I also monitor the battery voltage on my dash board. It's between 11.6 and 12v before I start the car, and between 13.5 and 14 volts when the car is running. There has been a few times when I started the car successfully that it would seem to lunge forward... I wasn't sure if it had anything to do with it, so I checked to see if the car would start in gear to see if I had a bad neutral safety switch. I also noticed the code 1552 pop up when I ran the diagnostic test on the dash,  came up as history... I was told that's from disconnecting the battery, and was also told it could be a short in the idle air valve... Now that I mention that I realize these starting problems occurred after I had my 02 sensor replaced to pass emissions for code pc0141, I passed emissions the next day but not even a week later the code popped back up, my service engine light will come on then go off again after a while, then come back on again... Not sure if this has something to do with it not starting at times... Could it be possible to have a corroded fuse panel.... anyways, thank you for your time.

Answer
Hi,
You have quite a bit here, but I will see if I can assist you. I never heard of that test you applied, but it has the same results for what I Wil tell you. If you turn on as many things that you can, the best way to check with the engine running is just to listen to the scream GM alternator put out and you will know it is charging.
Now, we have to get straight on twrminology.
When you say the engine does not start at times, do you mean nothing happens and the engine does not crank?
It is important for me to know what you mean by the engine does not start.
Don't start changing the idle air valve or anything else you have heard on a guess. That idle air valve short as you say is not a cause, but a symptom.
Pulling the codes from the car and finding one is too general to start changing parts.
Many service centers that have the same testing equipment a dealer has. You need someone to connect a GM scanner known as a tech II. That will pin point to the exact issue as to your problem.

Here is what the anti theft system is notorious for. Broken wires in the steering column that run to and away from the ignition lock cylinder. Column has to come apart and ignition and harness is required to be changed. Dealer charges $800. Or, you can go to a local alarm store and bypass the junk.
Very common for intermittent no crank.

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