Troubleshooting Trailer Wiring Connections on 2003 Chevy Silverado 4x4

Question

Question:

I think I have a ground problem on the truck side of things...truck didnt come with a hitch so I installed...also installed a plug 7 pin and 4 pin comboplugged into factory harness...I have constant power to yellow..even when truck is off...left directional both flash...right directional work fine...all running lights work...plugged into a buddys truck...everything is perfect...so I know its my truck...where are the grounds located on my truck 2003 Silverado 4x4

asked by: Paul

1

Helpful Expert Reply:

There are multiple ground locations on your 2003 Chevy Silverado 4x4. I don't believe that is your issue since you have the factory wiring harness. I recommend you use a circuit tester like # PTW2993 and test the pin functions of your trailer connector first. If they work with your grounded circuit tester perfectly, then trace your ground wire or create a new connection by splicing in and connecting the frame of your truck bare metal to metal.

If they don't work correctly, then remove your 7-way/4-way combo and test the wiring harness behind it with the circuit tester. Check for bent pins on the connector. If the US Car Connection harness works and there aren't bent pins, then replace your trailer connection with # HM40975.

If all else fails, use the 4-Pole Hardwire Kit with Circuit Tester # 18252 and then Universal Installation Kit for Trailer Brake Controller # ETBC7 to completely hardwire connection or splice into wiring you have confirmed works properly.

expert reply by: Jason S

1

Answer 1

My suspicion is that you have a poor ground connection somewhere on your trailer. The fact that everything works fine until the running lights are turned on is the dead giveaway. When the tail lights are turned on, the trailer lighting is drawing…

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Answer 2

What you are describing is normally the result one 1 of 3 issues: First, there could be some corrosion in or on the connectors on the vehicle or trailer side or both. Second there could be a bad ground. Bad grounds can cause all sorts of bizarre…

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Answer 3

Sounds like you have a blown fuse under the hood of your 2003 Chevy Silverado. The truck will have trailer wiring fuses/relays that are separate from the truck's turn signal fuses. That is why your truck's turn signals are working but the…

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Answer 4

What you are describing is normal. When you turn on your headlights the running lights of your trailer should illuminate. The running lights are dimmer than when the bulb is being used as a turn signal or a brake signal. Basically the trailer lights…

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Answer 5

The best place to ground a brake controller will be back to the negative post of the vehicle battery. I attached a picture that has a diagram of how brake controllers install.

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Answer 6

You are correct, you should only be getting output when the brake is applied, or the override switch is activated. It sounds like the controller might be bad, but to make sure, you should probably bench test it before tossing it. Use a circuit…

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Answer 7

Manufacturers can use any colors they want since there isn't really a standard for wire color and function. You will need to test each of the wires using a circuit tester such as #PTW2993 to determine the functions. Then you can attach them to…

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Answer 8

When wiring a trailer connector, it is best to wire by function, as wire colors can vary. We have an excellent wiring diagram on our website, I will provide you a link so you can look at it. If you are looking at the inside of the trailer connector…

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Answer 9

The manual lockout on your Atwood 85778 surge brake coupler is there so that you can back up the trailer without the brakes locking up on you. Yes you can safely tow your trailer with the broken manual lockout, you just have to make sure you…

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Answer 10

The correct replacement for a Demco Master Cylinder 05680-C is the Replacement Master Cylinder part #5650. I spoke with Demco to confirm this for you.

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Answer 11

If your current springs have 5 leaves then going to a 7 leaf spring will increase the height of the trailer a little and make the trailer more susceptible to sway. Regarding capacity if you go with springs rated higher than what is required it will…

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Answer 12

The correct replacement master cylinder kit we have for your Demco setup is the part #DM5918 which comes with the lock out replacement.

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Troubleshooting Trailer Wiring Connections on 2003 Chevy Silverado 4x4

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