Troubleshooting Trailer Brake Lights on Vehicle Side Harness on 2001 Chevy Express Van
Updated 07/18/2020 | Published 06/18/2020
Question:
I have a 2001 Chevy express van. on the trailer the brake lights dont work but running and turns both work. on the van all the lights work fine including the chmsl. I used a 4 way plug in tester and when you press on brake nothing lights up. checked all fuses
asked by: Scott
Expert Reply:
It sounds like there is an issue with the vehicle side wiring. Since you know there isn't a bad fuse, I recommend checking the wiring itself for a short using a circuit tester like # PTW2992 to determine the point where power stops flowing in your wiring. I also recommend checking the ground connection of the wiring harness like # 118240 as a bad ground that isn't bare metal to metal can have one function that doesn't work fairly easily.
If you don't have factory wiring, I recommend checking the module itself because if there is power going in but not out for that function then box may be bad. If that is the case then I recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118377.
Scott A.
7/18/2020
I'm sorry for taking so long to get back on this it tok awile to get fixed and then went on trip with vehichle. I had two other shops look at it and both said it was the "plug" they were wrong, I had allready proved that. Any way this light system (on Van) has 4 duel filiment bulbs on filement (on all ) works the running lights and the other is (on each side) turn signal on one bulb and brake on the other. This is the issue as it needs a converter box to keep the turn or brake from back feeding the other when hooked up to the trailer. I never found where the "box" is on this van however the last tech tapped into the existing brake light with a wire and ran to "plug" and ran 2 new wires from fuse block under hood to wire harness they also installed a new "box" I believe . I cant see any thing because it is all taped up. Anyway two separate bulbs (for brake and turn) requires a "box" to prevent back feed and this one just went bad. problem solved.