Front parks work but not rear. Burnt out Headlight switch?

[SUX2BU99]

After getting my truck re-wired from a 4-pin to a 7-pin trailer brake connector, a trailer brake controller and pulling around our new camper, my rear park lamps have quit. They are the same ones that light up the yellow clearance lights around the trailer too. The front park lamps still work though. RV place that installed the controller and put the 7-pin plug in said that the circuit they installed was still good but they weren't getting anything out of the headlight switch or apparently at the firewall where the fuse block is.

They said the park lamp circuit splits inside the headlight switch. I took it out last night and did some testing on the terminals but I"m not sure which is which. ANybody know? They were numbered. Does the park lamp circuit split front to back in the switch?

Otherwise I'd have to take apart the fuse block and I really do not want to do that! That sounds like a big mess. Or is it?  They said the engine half and the cab half may need separating and cleaning??

[Grim 82]

http://www.73-87chevytrucks.com/techinfo/wiring_diagrams/81-87_cab_inter_pg2.jpg
If I am reading it correctly I think they are mistaken in telling you that the circuit splits within the headlight switch. If it worked before you took it in and doesn't now it must be something that they did. Do your rear turn signals and brake lights still work?

[SUX2BU99]

There would have to be a split somewhere in the circuit from front to back and OEM usually does not like to split circuits at anywhere except a switch or a plug so I can see some merit in it being at the headlight switch although I can't really tell if that's the case by reading the diagram. I think I have a 77-80 wiring harness as that diagram seems to better match what I have but I really appreciate you giving me that link. My Hanes manual isn't nearly as detailed! The numbers at the terminals on my switch match that of the 77-80 digram. On that diagram, I see that "TAIL LP" has 3 different terminals and nothing that says anything about front park lights so maybe one is for front and one is for rear?  I bought a new switch anyway so I can compare between the two what works and what does not.

My rear brake lights work, and all of the signal flashers work.

[Grim 82]

My guess would be that it's split after the fuse since the parklamps share a common fuse, but I could be wrong. Hopefully the new switch fixes it. My instrument lamps all went out a while back, and it was the headlight switch. Let us know how it turns out.

[SUX2BU99]

Well the new switch did not fix it    But, I tracked down the wire that powers the rear park lights (brown wire, in a 4-wire connector plugged into the bulkhead connector) and I was happy to see I have power there! So it's somewhere down the line, most probably at some junction that the RV place tied into. They said already they checked it all out and it wasn't there issue but I'll track it down and figure it out.


What was of the most help was those diagrams. I trimmed the edges off each page and taped them all together to form one big wiring diagram that I keep rolled up in the garage. Pure gold!

[Captkaos]

Sounds like they broke the circuit.  I would start where they spliced.

[SUX2BU99]

Well I did end up finding the problem and yep, it was where they spliced. They used Scotch-loks, which I HATE, to tie in the park lights and turn signals so 3 of them and the one on the park lights was not snapped shut. This was after I checked the factory 4-prong plug and found I was getting power and was like    Then I saw that my park lights were working! So shuffling around the scotch-lok must have got it working again.

So I cleaned up that mess by removing all the scotch-loks and putting in bullet connectors instead. Yes, soldering is the ultimate solution but I like bullet connectors as they are a solid, dependable connection (if you use a toothed crimper) and can be taken apart if need be rather than cut apart like a butt connector. I then use heat shrink to cover all 3 re-done connections, then wrapped all exposed wiring that wasn't in loom, in electrical tape. I put some dielectric grease in the 4-prong plug too and on the ground that they installed in the rear crossmember. 2.5 hours of working on that and I was off to bed  lol

[Grim 82]

Glad you got it figured out. I am not a fan of the scotch-loks either.