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BLE 'BURBAN · 11-25-2007, 07:23 PM

Disconnecting the battery cable while the engine is running can,will & does cause a voltage spike for just a milisecond (18v - 36k volts) as witnessed by the tell-tale "spark". On older, precomputer controlled vehicles this isn't a real big problem. But on the newer vehicles it can fry out your PCM. I wouldn't recommend doing it on any vehicle regardless of age just for safe practice.

11-25-2007, 07:23 PM	#4
BLE 'BURBAN In the Forgotten far North. Join Date: Jul 2007 Location: Anchorage, Alaska Posts: 2,627	Re: alternator check Disconnecting the battery cable while the engine is running can,will & does cause a voltage spike for just a milisecond (18v - 36k volts) as witnessed by the tell-tale "spark". On older, precomputer controlled vehicles this isn't a real big problem. But on the newer vehicles it can fry out your PCM. I wouldn't recommend doing it on any vehicle regardless of age just for safe practice. __________________ 1987 R3500 CREW CAB DUALLY (BIG RED)Acquired 06/12/2015 1990 chevy suburban V2500 5.7L My cluster Mods-Nov 2007 overhead console Stereo install Round 2 Aug 2009 Heated/turn signal mirror upgrade Last edited by BLE 'BURBAN; 11-25-2007 at 07:24 PM.