Cab Light and Brake Light

[Dat620 77']

Hey yeah my cab light in my 620 wont work i can not figure out why it wont. but like i checked the fuses their all good the swithch seems to be good and, one of the door switches that signals the light is stuck in cant get it unstuck. and so i dont know what to do i could really use the help i even replaced the light. Kay also on my truck when i press on the brake both of the brake lights work but the left side only one light lights up.when their is suppost to be two like the right side what could be causeing this? Thanks Cody

[vindats1]

hi, had that happen in my 410...took the left side assembly completely apart and hand sanded all of it. That seems to solve the problem...but now that side is brighter than the other side...so need to do the same to the other side also. Good luck.

[DanielC]

Go to the following website. http://www.the620.com there are wiring diagrams there.

For the brake light problem, first make sure the bulb is good. If the bulb is good, use a test light to see if you are getting electricty to the brake light bulb socket. Then start working forward on the wiring harness under the truck, looking for problems. It is possible water has gotten into the wiring harness, and corroded the connections. It is also possible somebody messed up the wiring harness trying to hook up trailer lights at one time.

The cab light works like this. Power always goes to the cab light. The cab light switch grounds the lamp, and the lamp comes on. The door switches are just another ground, using wires to go to the door switches.

[datzenmike]

If one light works, then the harness is ok as both bulbs work off the one wire for the L, and one wire for the R side. It's either the bulb (bad) or bad connection where it twists into the socket. If that is good then the Black ground wire or the Light Green/Red wire is broken at the Left tail light. When you get this fixed be sure to wipe lithium chassis (white) grease on the bottom of the bulb. This will seal out water and prevent corrosion and not affect the electrical connection.

 

The door switches are almost certain to be corroded and not grounding to the cab properly. Try cleaning or replace them, again wipe some chassis grease on them.