Tail & marker lights inop, HELP

[Gumaer Falls]

2001 Ford E450, 7.3 turbo superduty diesel , 92k. Upon demo I’ve managed to somehow disconnect power to both my tail and marker lights (both front and back). I followed the power feed line and it looks like all these lights are ran in series off of one wire. All my other lights work - headlights, brake, turn and reverse all ops check good. I’ve checked all my fuses, both under hood and under steering column. I also checked the relay and it does click when I pull the light switch, leading me to believe the relay is good. All lights are also grounded properly. Any help is much appreciated!

[david.dgeorge07]

I found it helpful when diagnosing things of this nature to buy a wire tracer. You clip a transmitter onto the wire in question and then use a wireless probe to follow the path.

Also, just keep working the path with a volt meter, once hot.

You said the relay works, follow the power from the relay downstream (not accidentally upstream) until you reach the first light.

I’ve found that relays can have fuses both upstream and downstream.

Even if you have to start right at the switch, stick to the path like a tick on a dog and you’ll eventually ride it out to your problem.

[TheHubbardBus]

I also checked the relay and it does click when I pull the light switch, leading me to believe the relay is good. All lights are also grounded properly. Any help is much appreciated!

Better to use a meter... relays can click & still be bad.

[Gumaer Falls]

Watched about 10 hours of YouTube automotive electronics and dove in again with fresh eyes. Funny thing is I unknowingly cut the feed line about a month ago while removing the underbelly a/c condenser. I appreciate those that chimed in. Thank you!

[david.dgeorge07]

Most things make a lot of sense once you figure out what happened.

[TheHubbardBus]

Glad you got it figured out! And you learned new stuff, so it all served a purpose