Hey guys it's good to be back behind the wheel of a first gen. I just bought an 89 d350 from the original owners today for $2000. I'm kind of in a hurry tonight so gonna make it short and simple and get back on tomorrow. The brake lights,turn signals,and headlights all work but when I turn the lights on only the headlights come on. I don't have any parking, tail, or chicken lights working with switch on. Haven't had time to look at it so any info would help and like I said will check back in tomorrow. Thanks in advance

 

If it's anything like mine you'll get in there and find not only the switch fried but the harness block terminal as well. There's a sticky of running the harness wires thru the block terminal and onto the new switch with crimp-on female connectors. I'd add relays under the hood near the appliances so that the switch carries only the trigger circuits, ...

 

Checked the fuse? The exterior lights are all on one fuse.

 

Ok I'll check the fuse first and cross my fingers. If not I'll look in the sticky and get to work on that. Thanks for the help guys!

 

check the headlight upgrade in the, sticky to relay control high/low beams together, works awsome!

 

Ditto on the park light circuit being burnt out of the switch and its connector. I've fixed dozens of those. The draw of all the park and taillights is a lot for that circuit to handle, and it adds to the problem when people hook up a trailer. If the switch has indeed overheated, fix the problem permanently by adding a relay to the circuit for the trailer's taillight circuit to draw through. It's a better idea to add a second relay too for all the truck's tail and park lights to draw through, this will remove all the load from that circuit on the headlight switch.

 

Finally had time to look today and I got lucky. Checked the fuses and the running light fuse was melted so that told me something grounded out. By process of elimination I found the the amber marker light on the driver side dually fender was grounding out while plugged in. Thankfully it didn't melt the fuse box or leads to the box. When I get around to it I'm gonna do the relays for sure. Is there a good place to get aftermarket running and cab lights(Not a big fan of the old style cab lights)?Thanks again guys for the help!

 

check the sticky. Jim Lane did a great write up on cab light upgrade using LED`s!!

 

That's my next project. I'm going to run a hot 12 gauge wire to the back, then mount a fuse block and relays up under the bed rail for the tail lights and trailer lights.