My problem in a nutshell is that sometimes (not always) after driving for about an hour, if I turn off the engine
then try to start it in about 15-30 minutes, it will not start. No crank, no turning, etc. But if I come back in like 2 hours, it will start.
1) my local Cadillac dealership could not properly diagnose the problem. They first reprogrammed my car's computer=did not fix problem.
2) Then told me I needed to replace my ECM=I did that myself but it did not fix the problem
3) then I had them replace the ignition switch=but problem still occurs.
Any idea what it could be? Chip Key? Cylinder lock? Maybe just some bad wiring behind the wheel/dash? Not sure if I just have to abandon any hopes of fixing it and try to get rid of the car.
Also, some said maybe its the fuel pump
or EVAP cannister purge solenoid valve?
Not sure if it leads to any help, but do any of these items I came across the internet sound like a possible cause to you:
(1) ASK YOURSELF THE RIGHT QUESTIONS
What happens when you turn the key and try to start the engine?
If the answer is, "Nothing," you should check the battery, battery terminals, battery cables and ignition circuit to make sure voltage is reaching the starter. If the battery is low or has corroded terminals or loose cable connections, the starter may not crank because of low voltage. If the solenoid that energizes the starter motor is faulty or has loose electrical connections, it will prevent the starter from cranking, too. A faulty ignition switch, park/neutral safety switch on the transmission linkage, clutch safety switch on the clutch pedal or a wiring problem are other faults that can also prevent a starter from cranking.
(2) If the battery is low, the next logical step might be to try starting the engine with another battery or a charger. If the engine cranks normally and roars to life, you can assume the problem was a dead battery, or a charging problem that allowed the battery to run down. If the battery accepts a charge and tests okay, checking the output of the charging system should help you identify any problems there.
A charging system that is working properly should produce a charging voltage of somewhere around 14 volts at idle with the lights and accessories off. When the engine is first started, the charging voltage should rise quickly to about two volts above base battery voltage, then taper off, leveling out at the specified voltage. The exact charging voltage will vary according to the battery's state of charge, the load on the electrical system, and temperature. The lower the temperature, the higher the charging voltage. The higher the temperature, the lower the charging voltage. The charging range for a typical alternator
might be 13.9 to 14.4 volts at 80 degrees F, but increase to 14.9 to 15.8 volts at subzero temperatures.
If the charging system is not putting out the required voltage, is it the alternator or the regulator? Full fielding the alternator to bypass the regulator should tell you if it is working correctly. Or, take the alternator to a parts store and have it bench tested. If the charging voltage goes up when the regulator is bypassed, the problem is the regulator (or the engine computer in the case of computer-regulated systems). If there is no change in output voltage, the alternator is the culprit.
Many times one or more diodes in the alternator rectifier assembly will have failed, causing a drop in the unit's output. The alternator will still produce current, but not enough to keep the battery fully charged. This type of failure will show up on an oscilloscope as one or more missing humps in the alternator waveform. Most charging system analyzers can detect this type of problem.