Reversed Polarity 1994 C220

Aug 12, 2004 3 Replies
D

Someone who will remain nameless reversed the polarity while hooking up a non-mercedes-standard battery to my C220. Every engine control fuse has blown and blows when replaced either as soon as it's installed or when the ignition is turned on. Is the entire electrical system fried or does anyone have a good idea where to search for the short? The engine will run, a little rough (may be other problems), but dies as soon as I lift off the accelerator, which didn't happen before the polarity reverasal.



Thanks, Dave


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T

Yikes! What a nightmare.

Some things come to mind. The alternator's voltage regulator (diode type) may be fried and allowing the positive to ground. The diodes can be replaced if necessary. Suggest you temporarily disconnect the wires to the alternator to see if the massive shorting problem clears, or not.

I'd say the good news is that the engine runs indicating that the ECU may be OK.

The lack of idle may be due to the idle speed controller not functioning, either from no power or that it's fried.

Modern cars' electrical systems are very complicated and this won't be cheap to fix. Each subsystem needs to be isolated and tested - buy dozens of fuses or an amp meter to check the flows.

Repairs might be covered under your comprehensive insurance policy.

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