Trailer Lights Gurus--Got a Question.

[Tony H]

Bear in mind again that there is no power to the 4pin trailer connector UNLESS the pickup lights are ON. The trailer lights all work perfectly then.
Nothing can work if there is no power. The issue has to be in the pickup wiring, right?

If you put a meter on the ground pin on the truck connector and the other meter lead to another socket (green or yellow wire)on same connector, will you get voltage on the meter when stepping on brakes? That will let you know that truck wiring is correct to that connector

 

[npalen]

If you put a meter on the ground pin on the truck connector and the other meter lead to another socket (green or yellow wire)on same connector, will you get voltage on the meter when stepping on brakes? That will let you know that truck wiring is correct to that connector

I don't blame you for not reading through all the posts of this long thread but the problem, which was operator error on my part, has been solved. Thanks.

 

[npalen]

Having said that it has been solved, I did notice today that the brakelight function is not working for some reason. Works on the pickup but not the trailer. All the other trailer light functions seem to work fine..

I don't blame you for not reading through all the posts of this long thread but the problem, which was operator error on my part, has been solved. Thanks.

 

[WranglerX]

Gads hope this tread doesn't go on to 202 pages like rounded off drain plug thread....

 

[npalen]

Gads hope this tread doesn't go on to 202 pages like rounded off drain plug thread....

HaHa It ain't over till its over.
So why wouldn't the d**n brake light work when everything else does?

 

[Midniteoyl]

HaHa It ain't over till its over.
So why wouldn't the d**n brake light work when everything else does?

Your wire colors were incorrect so maybe you have the the 'brake/turn' wires of the LEDs actually hooked to the running light wire?

 

[npalen]

I wondered about that so switched them and didn't make any difference. Should see a light either way though when the brake is depressed. Right?

I do understand that the lights wouldn't be as bright if they were wired backwards since only the "tail light LED's would be lighting when brake is depressed.

Will investigate further to see if I'm getting any voltage at the trailer light connector when brake is depressed. (probably not)

 

[Midniteoyl]

I wondered about that so switched them and didn't make any difference. Should see a light either way though when the brake is depressed. Right?

I do understand that the lights wouldn't be as bright if they were wired backwards since only the "tail light LED's would be lighting when brake is depressed.

Will investigate further to see if I'm getting any voltage at the trailer light connector when brake is depressed. (probably not)

Might also need to add a resistor like shown earlier in the thread.

 

[WranglerX]

Check connector on truck first.... If its good, then trouble shoot trailer... IF brake pedal pressed you should have 12volts at yellow and green wires at plug on truck...

IF turn signals work at trailer the trailer wiring is good.... IF you take small 12 volt battery (battery charger or jump box) and a clip cord to connect trailer plug ground wire to minus (-) side of battery supply and use another clip cord to put 12 volts from battery plus(+) to each of the corresponding wires (yellow/green/brown) and proper LEDS illuminate on trailer, all your problems are in truck....

At trailed plug using just a 12volt battery (or battery charger)
put ground on trailer white wire
put 12 volts on brown wire, tail lights ( and side markers if equipped) come on.
put 12 volts on green wire bright LED for RIGHT side stop/turn comes on.
put 12 volts on yellow wire bright LED for LEFT side stop/turn comes on.

If you get these results your trailer wiring is good..... PERIOD...

Also find this tool for trouble shooting best ever.... Lamp "on" you have both voltage and ground.. Lamp off, either voltage or ground or both missing...

Just to be clear I have 4 multimeters, 2 analog and 2 digital, and this $5-10 tool is preferred for automotive wiring trouble shooting (non computer circuits) ...

And yes I do get deep wiring, this is a in process picture of developing a full wiring harness for VW DUNE BUGGY with all full road legal wiring for lights and engine instrumentation...

And done,,,

 

[aczlan]

Might also need to add a resistor like shown earlier in the thread.

Shouldn't need one, I would bet lunch on it being a wiring problem.

Aaron Z