Running light problem

[RLF]

Truck plug is good along with fuses. All running lights are not working except one, it is the lower red rear on passenger side. I have changed bulbs in a couple of them this was no help. Checked after that and no power. Strange one is working and the rest are not. Help is appreciated. I have a 2018 Passport

[chuckster57]

I would bet that light is at the end of the run. If the socket has no power, remove the light fixture and look for a failed crimp.

[RLF]

The only lit light is probably at the end of the run.

[chuckster57]

Oops, I guess I misread. I’m thinking a bad ground?

[RLF]

Would the only lit light usually be on the end of the run or the start?

[chuckster57]

Running lights are usually daisy chained, so it’s hard to say. Unfortunately you need to start at the front and look for a failed connection. Bell connectors are common and if it’s not crimped, 1 or more wires can back out.

[RLF]

Just wondering, if there is a failed connection should that light, which should be at the end of the line be burning. Thanks for all replies!

[chuckster57]

I’ve seen some weird things so I can’t say for sure. It is odd that one light works.

[wiredgeorge]

If I were looking for a bad ground I would go to the next marker lamp beyond the one working and check the ground there.

[flybouy]

If none of the clearence lights (including the 2 tail lights) are working then the first thing I'd do is jumper the 7 way plug on the trailer to apply voltage. If the lights work you aren't getting power from the truck. If they don’t work then check the ground.

[wiredgeorge]

Originally Posted by flybouy

If none of the clearence lights (including the 2 tail lights) are working then the first thing I'd do is jumper the 7 way plug on the trailer to apply voltage. If the lights work you aren't getting power from the truck. If they don’t work then check the ground.

I bought an inexpensive gizmo to check 7 way pins on both sides of the connectors.

[RLF]

On checking the next light would you go up or over? On checking the seven way both ways, where did you get it? Thanks for the replies!

[wiredgeorge]

I believe I bought mine on eBay:
https://www.ebay.com/sch/i.html?_fro...er&_sacat=6028

[RLF]

Thank you wired. Going to purchase. A handy tool!

[chateaunoname]

I replaced my running lights last year and had the positive and neutral reversed. On LED lights you will not blow a fuse if backwards, they just will not work. Just a guess.

[61Hawks]

Interesting my running lights will work for a bit then all go out then come on again whenever. All my brake and turn signals work. Not sure what it is.

[LHaven]

Originally Posted by 61Hawks

Interesting my running lights will work for a bit then all go out then come on again whenever. All my brake and turn signals work. Not sure what it is.

Could be one pin in your 7-pin connector needs tweaking and/or cleaning. They do get loose sometimes.

[RLF]

Ok. Plugs on truck and trailer are good. Does anybody know where the first connected light on the wires path is and where is the last? My rv is a passport but would guess most Keystone would be similar. Would lights on the string burn until you get to the problem and all lights after would be out? Going to get this fixed yet.

[flybouy]

Originally Posted by RLF

Ok. Plugs on truck and trailer are good. Does anybody know where the first connected light on the wires path is and where is the last? My rv is a passport but would guess most Keystone would be similar. Would lights on the string burn until you get to the problem and all lights after would be out? Going to get this fixed yet.

There are no wiring diagrams. Follow umbilical plug back until you find a junction box. The wires will connect at that point. The only thing you can logically assume is that Keystone would take the shortest path to use the least amount of wire. The lights are run in parallel so if one goes out the rest stay on. Have you checked each light socket for power?

[JRTJH]

Originally Posted by 61Hawks

Interesting my running lights will work for a bit then all go out then come on again whenever. All my brake and turn signals work. Not sure what it is.

The brake/turn signal lights are wired to a separate circuit from the running/tail lights. THEY DO NOT INTERFACE OR CONNECT TO THE SAME PINS ON THE TOW VEHICLE UMBILICAL.

If the running/tail lights are intermittent and the brake/turn signal lights work properly, I'd first suspect a loose connection in the junction box where the trailer 7 wire umbilical connects to the trailer wiring harness. That box is located on the tongue A-frame or the front bulkhead on travel trailers and usually is in the pinbox on fifth wheel trailers.

The running/tail lights are on the GREEN wire connected to pin #3 on the trailer connector which is the first pin clockwise from the plug index key.

The LEFT brake/turn signal is on the RED wire connected to pin #5 on the trailer connector which is the second pin clockwise from the plug index key.

The RIGHT brake/turn signal is on the BROWN wire connected to pin #6 on the trailer connector which is the second pin COUNTER clockwise from the plug index key.

NOTE: The "Keystone color code" is not the same wire colors as the GM/FORD/RAM color code, so don't attempt to follow a "red truck wire" to the trailer harness.... THEY CHANGE COLORS !!!!!

Here is a link to the Keystone wiring color code: https://keystone-rv-dealer-app.cdn.p...box_Oct20b.pdf

These diagrams are "standard industry diagrams" and are not specific to Keystone trailers. You can visualize where the pins are located with reference to the index key on the plug. Take note that the colors are different, even on these two diagrams...