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No 12V Power or Running Lights on 7-Way Trailer Connector on 2004 Chevrolet Avalanche


i have no 12 volts or running lights at the 7 way trailer hook there a fuse thath controls both of these?

Expert Reply:

If the 7-way trailer connector on your 2004 Chevrolet Avalanche is part of a factory-installed tow package (if it is it should have a GM logo on it), then all wiring and fuses should be in place as part of the tow package. As you noted it is still possible that there may be fuses missing from the accessory fuse block in the engine compartment, or there may be blown fuses. It could also be that the wire lead for the 12V+ circuit is not connected at the fuse block.

Please note that trailer 12V power and running lights will be on separate circuits with separate fuses.

If the vehicle 7-way connector is an aftermarket installation it may have an in-line fuse somewhere along the 12V power wire running under the vehicle. If the 7-way is aftermarket you can trace the black power wire back from the 7-way to the battery to check for a blown fuse.

Please refer to the photo provided, which illustrates the Accessory Fuse Block within the engine compartment of a Chevrolet truck. Arrows indicate the location of the required 40-amp fuse (orange) and of the wire for the 12V circuit to the 7-way that must both be in place to power the 12V trailer circuit .

You can also check the fuse block for a fuse location for the trailer running lights. Replace that fuse if blown or missing.

Once you have confirmed that all fuses and wiring are in place, if you still do not have 12V and running light signals on your factory 7-way, try disconnecting the plug from the back of the 7-way (behind the bumper). Use your circuit tester, such as # ALL640595, to test the pins on the plug. With your headlights on, ground the tester and test each one of the pins on the plug for the 7-way. You should detect a signal on two of the pins, one for 12V and one for running lights. If signals are present on the plug but not the 7-way, then you can replace the 7-way connector with # 30955.

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expert reply by:
Adam R

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