Testing the 7-Way Functions on a 2001 Chevrolet Suburban and Trailer

Published 05/12/2017

Question:

Lights on my 2001 suburban 1500 work fine - brake, turn signals, running lights hooked up 7 to 4 wire flat adapter to run my little trailer and the lights on the trailer intermittent or reversed - left turn signal flashed to right side trailer light Installed a new brake controller and rear connector on the sub, connected my brand new just bragging 18ft flatbed sub lights remain fine, controller runs the brakes fine, but now no running lights at trailer and the same goofy reversed turn signals at the trailer first pass Im trying to figure out if this is a component failure or wiring issue perhaps something about this sounds familiar to you - its new to me

asked by: Greg K

Expert Reply:

It sounds to me like it is a wiring issue. What I recommend doing is using a Circuit Tester like part # PTW2992 and test both the functions on your Suburban and your trailer.

On your Suburban these are what the functions should be when you are looking at the 7-Way from the outside:

1 o'clock - 12V Power
3 o'clock - Right Turn & Stop
5 o'clock - Brake Controller Output
7 o'clock - Ground
9 o'clock - Left Turn & Stop
11 o'clock - Tail & Running Lights
Center - Reverse Lights

Your trailer's 7-Way connector will mirror these pins as illustrated in the attached pictures (under 7-Way Traditional).

When testing your trailer you will want to use an alternate power source like another 12V battery to test each function.

If everything is wired correctly let me know and I will help you troubleshoot further.