Freightliner loosing marker lights with headlights

Have you allready replaced headlight switch?

 

I agree with Baha. Probably the headlight switch.

 

Switch, if you rule out the ground.
Did you disconnect the headlight from harness. The short could be in the head light or one of the other bulbs.
Sorry see you did that. How about the fuses.

 

I just had this problem with my FL classic. I know this isn't the "right" way to fix it but it worked for me and got me down the road.

On the back of the headlight switch it will look something like this
|* |
| |
|* |

Get some wire and jump the 2 with the * beside them and your lights should all turn on with headlights on. My interrupt switch doesn't work anymore with this setup. And if you push the switch down for marker lights only, the right low-beam will be on.

I tried a new switch and had the same problem. My mechanic looked at it and couldn't find the problem without spending a lot of hours on it. I will run with it as is. I also had a problem with the high beams not working at all anymore. The back of the relay panel had corroded away and some relays needed replacing. All good to go again now, though.

 

#### you road grime!!!

 

I didn't want to bring up an old post but this is amazingly similar to what is happening with me --

If I cold start the truck and turn on my running lights and begin to drive, after about 10 or 20 minutes (It varies) a few miles of driving over 40 mph - my marker lights begin to blink on and off (Starting in the rear of the box) and I hear the relay clicking then they all shut off.

My problem is more complicated to myself in that my tractor was converted into a box truck and I am not sure where to begin searching for this corrosion - is it something I can find without taking the fuse panel out? How can I test this issue?

I wanted to speak to some of you about this issue on the forum and find other possible points of failure.

I have replaced the marker interrupt switch and running light headlamp switches brand new from Freightliner.

I have also swapped the trailer tail marker relay on the fuse panel inside the cab - Please respond, I'll be most grateful.

 

Pretty much the same problem with the lights. Most times it is corrosion in the system. Check each light socket first. Then connections. Look real close around the back of lights. Some LAZY techs will test the circuit using the sharp probe thru the insulation to check for power or continuity. This will leave a tiny whole for salt to corrode the wire and it will break. But you can't see it easy. Good luck.

 

Did you ever get an answer ro this problem? We are having same issue.