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Engine shuts off randomly while driving, also random no or weak cranking - Olds Intrigue

ed_99_intrigueed_99_intrigue Posts: 2
edited September 2014 in Oldsmobile
The ignition switch turned out to be the cause or these and other random issues that became a daily occurrence within a few weeks of first incident. Other symptoms were: car would usually restart after shutting itself off, with emission light on and giving codes crankshaft position sensor and camshaft position sensor. Also trip odometer would have reset to zero miles. (regular odometer unaffected) Car would usually crank fine when cold, but attempting to restart after stopping for gas, etc. would act like nearly dead battery, bad cable connections, bad starter motor, with clicking sounds interspersed with very sluggish cranking.
You don't have to replace the ignition switch to get rid of the problem, at leaste not in my case. Here's what worked for me: Every time you start the car do this first:
Put key in ignition, turn to accessory position, put and hold foot on brake pedal, put left or right blinker switch on and move transmission selector into reverse.
Finally, rotate key to on and, without cranking, look at the emission (service engine soon) light. If it is as bright as the other lights, then put transmission in neutral (or park but keep the foot on the brake) and rotate the key to start and the engine should crank normally and start.
If the service engine light is anything but steady and bright, such as very dim, or even not lit at all, then go back to accessory and back to on and look again. It may take several back and forths, but eventually it will come on bright, and once it does, leave it there, go to neutral or park and turn key to start.
The cranking should be normal and the engine should start right up and there should be no more random shutting off, but you must do this procedure every single time you start the car. If the lamp is dim or completely out when doing this procedure, it is definite proof that the ignition switch is the true and only cause of the erratic symptoms.
After a few weeks, again, at least in my case, the light was always bright the first time, but I do not plan on letting up on this little procedure.
I think what happens is that the heaviest current that this particular switch contact carries occurs when the turn signal lamps(front, rear, and cornering) brake lamps and reverse lamps are all on when the switch contacts are closed. The lamps are all incandescent lamps, and I think "normal" (not CFL or LED, just regular tungsten) lamps draw some ten times their rated current the first fraction of a second power is applied until they get glowing white) There are other switch contacts in the ignition switch but the ones that can shut the engine off are the ones that are closed only in run or start, not in accessory position. The heater fan motor and radio are controlled by different contacts that are on in accessory and run, (but not start) so it won't help to turn those on along with brake, reverse, and turn signal lamps, and other heavy current things are powered through relays which draw little current from the ignition switch.
The other lamps such as oil low, coolant low, etc. are powered through a lamp relay and only the service engine soon lamp (not to be confused with service vehicle soon lamp) is powered by the engine control module (ECM) which gets its power from the start-run contacts of the ignition switch. So only this one lamp is the indicator of whether the switch contacts that make the car run have made a good or poor connection. It also affects cranking because the start relay (the little one that the security system goes through not the big one on the starter motor) gets its power from the same set of contacts. So the one set of ignition switch contacts can make a running car shut off and/or make it not crank too.
If you think back to the times the car just shut off when driving, it was probably during a brake pedal tap or getting ready to turn a corner, and if you didn't notice that the engine was off until you needed the power steering, the delay would keep you from realizing that an increased electrical load, such as putting on the turn signal, was the real moment the engine shut off.
Sorry about the length of this letter, but it beats taking out the radio, AC control panel, and instrument cluster panel and you always have a reliable indicator of what will happen when you try to start (or restart) the engine.
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