Running Lights Work But Brake Lights and Turn Signals Do Not Work on Coleman Camper
Question:
My running lights work but brake and turn lights do not
asked by: Tracey C
Expert Reply:
The best way to start troubleshooting your truck and trailer is to disconnect the two and test each one separately. If you have access to a different tow vehicle or trailer you can test using one of these to isolate the problem to either your truck or camper.
Inspect both the vehicle and trailer connectors for signs of dirt, discoloration or corrosion. Even very slight greenish or whitish discoloration on the connectors can interfere with signal transmission. You can try cleaning the connectors with a spray-on contact cleaner if they show any such signs (and apply a protective dielectric grease such as # 11755 to keep out moisture). If this does not correct the problem you can begin testing.
You can start by testing the trailer connector on your truck. Confirm that the lights on the vehicle operate properly. Once you know the lighting functions on the truck work you can use a circuit tester such as # PTW2993 to test each lighting function at the 4-pole one at a time.
Apply the ground for the tester to the exposed ground pin on the 4-pole flat connector. (Please refer to the photo provided.) Have a helper engage the left turn signal. Apply the tester to the pin corresponding to the yellow wire. Repeat for the right signal on the pin for the green wire. Repeat your test of these same two pins with the brake pedal pressed. If you detect the correct signals you can move on to testing the trailer. If not, test the wires leading to the 4-pole; it is possible that the wires are carrying the signals but the 4-pole connector may be damaged or corroded. If the wires have the correct signals but they do not appear on the 4-pole pins then you can replace the 4-pole connector using a part like # HM48030.
You can directly test the trailer lights using a 12V battery. Connect the battery negative terminal to the ground pin on the trailer connector. One by one connect the battery positive terminal to each of the three pins on the trailer 4-pole. If the trailer lights function correctly when directly powered in this way then you know the issue is not within the trailer wiring. If the lights do not work when directly powered from the battery then you will need to carefully inspect all trailer wiring from the 4-pole back to the individual trailer lights. Check for wires with cracked or worn insulation, loose wires or any that may be rubbing against or pinched between trailer components. Repair or replace any such wire as needed.
I have also linked an article on trailer wiring that includes additional guidance for troubleshooting.
Products Referenced in This Question
Dielectric Grease for Electrical Connectors, 2 oz.
- Accessories and Parts
- Trailer Wiring
- Wiring
- Dielectric Grease
- LubriMatic
more information >
Hopkins Endurance 4-Way Flat Trailer Connector w/ 48" Harness and Ergonomic Pull
- Trailer Wiring
- Trailer Connectors
- Vehicle End Connector
- 0 - 5 Feet Long
- Plug and Lead
- 4 Flat
- Hopkins
more information >
Product Page this Question was Asked From
Plug-N-Tow (R) Vehicle Wiring Harness
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- No Converter
- Custom Fit
- 4 Flat
- Hopkins
more information >
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