I had always thought that one should never leave the ignition on and not running for more than a few moments,at least no more than 3-5 minutes due to module fry- am I wrong? If any one can clarify,please do so! Thank you!

 

Not sure about your question but for years ive left my key on listening to the radio while working on stuff. Never had a issue. Id say its A okay!

 

That used to be the case years ago, when ignition systems used points and a condenser. Leaving the key in the run position could burn up the points and/or ignition coil. Now that everything is computerized, it doesn't matter. Turning the ignition switch to the accessory position draws less current so the battery will last longer.

 

Right,When I'm parked listning to the pod or reading I always use the ACC position,but for long term (45 min) voltage testing doesn't that have a potential to fry the coil or module? I believe it did in the early GM electronic ignitions,didn't it? BTW,when I used to go long-term camping in the San Juans in my 78 GMC, I could leave the key in ACC for up to 5 days to power ham equipment without having to start it! Thanks for your input!

 

The coil, module, and PCM are all powered with the ignition in the RUN position. The module has a heat sink and will disipate the heat, which is minimal if the engine is not running. The coil is only grounded when the module supplies ground to it, which it only does when the PCM commands it to, so no heat is generated. The PCM also has a heat sink built in to it, although no switching activity is present if the engine is not running. Technically it shouldn't hurt anything to leave the ignition on, but why take the risk when you can just use ACC position?