10-Amp Fuse Keeps Blowing in 2011 Nissan Frontier When Using Curt T-Connector Wiring Harness #C56225

Question:

I bought this product have no running lights. Checked the fuse and the 10 amp fuse was blown replaced the fuse and have now blown 3 10 amp fuses and a 15 amp. Any idea why this keeps happening? I appreciate any assistance.

asked by: Mike E

Expert Reply:

If your Frontier running light fuse blows when you connect your trailer there are several potential causes. It could be that the trailer lights are demanding more current than can be provided by the harness, although this is unlikely since the Curt T-Connector Harness # C56225 can deliver up to 7.5 amps per circuit which is higher than many similar products. If your trailer has been modified by the addition of extra running lights these may demand more current than can be provided. What is more likely is that there is a fault in the trailer wiring.

If possible begin your troubleshooting by using your Frontier with another trailer that is known to have properly functioning lighting or try your trailer with another 4-pole-equipped tow vehicle. If you have an opportunity to do either of these things then you will quickly isolate the problem to the vehicle or trailer.

You can also use a circuit tester such as the Draw-Tite # PTW2993 to test the pins on your vehicle 4-pole harness for the proper running light signal with the trailer disconnected. Please refer to the photo provided; this shows where to ground and apply the tester probe (the pin for the brown running light/tail light wire). If you detect a steady signal on this pin when the Frontier headlights are on then there is no issue within the vehicle and you can move on to the trailer.

Inspect the trailer connector for any signs of damage, dirt or corrosion. Sometimes trapped dirt, water or severe corrosion can cause two circuits to be bridged; this could be causing a short that can blow a fuse. Inspect all trailer wiring from the connector all the way back to the light fixtures for loose connections, any signs of cracked or worn insulation, or pinch points near the suspension components. Check for secure attachment of the ground wire connection at each running light and at the main trailer ground.

If there is no problem found on the trailer then there may be a wiring problem somewhere on the Frontier and you will want to go back and check the installation and relays/fuses again according to the instructions, which I have linked for reference. I have also linked a video that should help.

Please note that it is not recommended to substitute higher-value fuses than what is specified by the vehicle manufacturer. Doing so essentially negates the benefit of fuse protection.