Troubleshooting a 2007 Volvo XC90 W/ No Turn Signals and Brake Lights
Updated 10/27/2025 | Published 03/10/2025
Question:
2007 Volvo xc 90 curt trailer kit install. So light come on but turn signal and brake lights don’t work. Lights come on immediately. With a 4pin tester both the left and right indicator lights come on immediately when plugged in. Checked ground and seems to be grounded correctly but with a multi meter both the Left and right are powered at 3-4 volts even with the car off. So not sure what that means. Seems the controller is faulty? When the headlights are turned on the taillight indicator on the tester lights up like it should. Pic is with keys out of the ignition. Thanks for any help, Nelson
asked by: Nelson C
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Expert Reply:
Hey Nelson, so if you've already checked your wiring, grounds, and voltage then it's most likely an issue with the controller. The only other thing you could check is the fuses, and see if one maybe blew, but if not, then it's likely an issue with the controller.
Before you replace your brake controller though, I'd check the trailer's wiring especially that 4 pole to absolutely rule out wiring as the culprit. If that all checks fine, then you'd need a replacement like # 90195.
If there is anything else I can do for you, please feel free to drop a comment and let me know!
Product Page this Question was Asked From
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Powered Converter
- No Tow Package
- 4 Flat
- Plug and Lead
- Plug-In
- Hidden
- CURT
more information >
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Lazer S.
10/27/2025
Hey Nelson, did checking the trailer wiring or fuses help narrow down the issue with your Curt wiring harness? Knowing what fixed it could really help others troubleshooting similar light problems.