1997 Chevrolet Silverado electrical from computer plug C1

1997 CHEVROLET SILVERADO
278,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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OZBALL
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trying to determine the most probable place to locate a short in the line of the blue C1 plug going to the computer. if i disconnect the plug all is fine excpet it wont start if i plug it in it pops the ECM1 fuse. what is the most common cause for this kind of short/ failure.
Oct 26, 2014 at 4:18 PM
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CARADIODOC
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Nothing is common, and I don't know which circuits that fuse feeds. A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

Observe if the bulb starts out bright for one or two seconds after turning on the ignition switch, then goes dim until you try to crank the engine.
Oct 26, 2014 at 8:35 PM