Help, No power to vehicle despite good battery and power to fuse block

Adam Jinks

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Hello all, I have a 2013 Yukon XL SLT 2WD that has zero power to the truck. I have full voltage at the battery, full power down stream of the mega fuse that is on the positive battery terminal, full power when I remove the under the hood fuse block and test the positive power source at the fuse block. But when everything is installed it will not start, crank, no door chime or dome lights, no power to rear hatch, no horn etc. It will not crank when I remove the starter relay and jump it there. It is like no power is leaving the main fuse block/wiring harness/junction box. On Friday I started it and drove it three times. The fourth time I went to start it, truck dead. Ran all of the above diagnostics, removed fuse block, re installed, tested for power everywhere I could think of with my multi meter, went to put something in the cab only to notice the lights were on. It fired right up, ran for the rest of the day, would not start Saturday and has not started since despite repeated the process. Battery has been confirmed good. Any thoughts before I roll the dice and spend over $200 on a new loaded fuse block? Any help would be appreciated, I am stuck. Literally and Figuratively.
 

Geotrash

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Hello all, I have a 2013 Yukon XL SLT 2WD that has zero power to the truck. I have full voltage at the battery, full power down stream of the mega fuse that is on the positive battery terminal, full power when I remove the under the hood fuse block and test the positive power source at the fuse block. But when everything is installed it will not start, crank, no door chime or dome lights, no power to rear hatch, no horn etc. It will not crank when I remove the starter relay and jump it there. It is like no power is leaving the main fuse block/wiring harness/junction box. On Friday I started it and drove it three times. The fourth time I went to start it, truck dead. Ran all of the above diagnostics, removed fuse block, re installed, tested for power everywhere I could think of with my multi meter, went to put something in the cab only to notice the lights were on. It fired right up, ran for the rest of the day, would not start Saturday and has not started since despite repeated the process. Battery has been confirmed good. Any thoughts before I roll the dice and spend over $200 on a new loaded fuse block? Any help would be appreciated, I am stuck. Literally and Figuratively.
Check your ground connections. They are notorious culprits on these trucks. Remove the ground straps from their mounting points on the engine block and firewall at a minimum and clean with a wire brush. Another culprit is internal corrosion in the battery wiring itself. Very hard to spot from the outside.
 

davidavidd

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@Adam Jinks if you have basic knowledge of electricity bypass your main battery cables, take two jumper cables (a good quality ones) and connect the negative directly to the negative of the engine block and the positive to the mega fuse (or to the fuse box directly). It may seem like a simple test but I have seen battery cables that look perfect externally but are rotten or broken inside. Do not underestimate either the weather or rodents.

You should also do a voltage drop test, remember the difference between voltage and current and you may have the correct voltage but not enough current for the vehicle's computers to "wake up" and activate, specially the ECM and BCM.

All electrical testing should be done with safety glasses, gloves (preferred) and a fire extinguisher at hand (ABC or CO2). Beware of a short circuit and check before connecting that the terminals are not making contact with each other or the positive touching the chassis of the truck.

Sorry if my English is not the best, I hope to help you.
 

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