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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: cwest on September 02, 2015, 07:13:16 pm
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86' K20. For a while now I've had a flickering battery gauge. I took real notice when driving at night and all of the trucks lights dim randomly, sometimes to the point of no light at all. I Googled it and the first thing that popped up was bad alternator, so I swapped in a new one, to which nothing changed, still flickering lights and battery gauge. I jiggled every wire I can see looking for a short, but nothing. The only thing I've found that distinctly causes a dim in lights is if I step on the rear passenger side bumper. Does this still sound like a short somewhere, or is this something specific someone has dealt with? It happens predominantly after the truck is up to temp as well.
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How strong does the starter crank the motor?
It sounds like a connection problem... somewhere.
To begin, take a thorough look at the following:
- battery terminal and cable condition - realize that cable strands can corroded and break inside the cable jackets where hidden from view. If you see green fuzz, replace the cables with at least 2-gauge all copper battery or welding cables.
- battery cable connections to the battery, starter and engine block or alternator bracket
- ALL of the remaining grounds (battery-to-radiator support, battery-to-frame, right rear cylinder head-to-cab, instrument panel-to-cab, rear lamps-to-bed sheetmetal, and bed-to-frame)
- tightness and condition of all wires connecting to the alternator
- condition and tightness of the fusible links at the starter solenoid and firewall junction block
- heavy-gauge red B+ feeds as they run through the conduit in the vicinity of the right exhaust manifold and up behind the engine, inspecting for burning and/or chafing
- heavy-gauge red B+ feeds where they pass through the firewall bulkhead connector, inspecting for heat stress and melting of the connector body
- the splice in the heavy-gauge B+ feeds taped into the harness under the dash near the fuse block (this one is a pain - save it for last)
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Double check grounds, battery to frame, frame to engine, and frame to cab. Sometimes these corrode internally too, so replacing to rule it out may be the best choice.
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The starter turns the engine normally except about 1/10 starts it stutters for a half a second before cranking. Having said that I'll probably start with the starter connections, and then the rest of those suggestions. I'll you guys know, thanks for the replies