Lost Tail Lights and Side Marker lights

[Booyah the monkey]

Okay, all my lights were working fine except the license plate light so I took one off from a parts Scout and was wiring it but didn't get any light. So I switched the bulbs and nothing, so I decided to switch the wires (stupid) and when I did I lost all the side marker lights and the taillights. However the light lights work when I hit the brakes but not when I pull the light switch. So I disconnected the license plate light altogether. There are no melted wires and there was no smoking. So I checked behind the pull switch to turn on the lights where the wire harness connects to the light switch and everything is connected fine. I also checked under the rear where the taillights and side marker lights connect and all the connections are fine. The panel lights work fine and so do the brake lights in rear and from what I understand they are pretty closely connected to the side marker lights. I am stumped and don't know what to check next. Any help is greatly appreciated. Also, I took a look at the electrical setup in the manual but I don't understand it.

- okay, I am making a little progress. I found out that when I hit the brakes that not only do the tail lights turn on but so do the side marker lights. I have no idea how this happened because prior to messing around with the license plate light everything was working fine. When I incorrectly connected the license plate wires I watched the tail lights go out.

 

[Scoutboy74]

Booyah, your monkey has been playing tricks on you. I'm willing to bet you your next pay check that you have a bad ground. First thing you should do is provide us with some specific vehicle data any time you post a question. I know this is a Scout, but beyond that...hey, they did go through some changes over the years. If you get tired of repeating yourself, you can always fabricate a custom signature with pertinent vehicle information like a lot of us do. That way it will be there automatically every time you post. Now, if your Scout has metal rear light housings, they get their ground through contact to the sheet metal via an upper and a lower fastening screw. This is a very poor grounding system that is very prone to corrosion issues. If you have a later Scout with the all-plastic housings, there is a separate ground wire that contacts the sheet metal for ground. Its damn near as craptastic as the metal housing version. In either case, you need to remove the lens and/or housing from the body so you can examine and clean the grounding contact locations. Do that and report back with your results. If that doesn't solve your issue, we'll delve deeper. We have the technology.

 

[Booyah the monkey]

Thank you for the reply. The Scout does have the metal housing and I will check the grounds tomorrow. I guess I can put the headlight switch back in. Your confidence in a ground issue reassuring.
I noticed that there are two wires that feed into the upper light on the taillights. I thought one was positive and one was negative but I did notice that the lights brighten up a lot once they are screwed in completely (grounded), I'm not very good at connecting the dots, I usually just look at them. So are the two wires that feed into the top light bulb for separate uses? I am guessing one is for brakes/tail lights and the other is for turn signals? Also, would you happen to have a diagram of which wires plug in to which inlet where they all connect.
Again thank you for your help, when it comes to the Scout manual and electric issues the manual might as well be in french.

 

[Scoutboy74]

The reason for the two wires to one bulb is because the bulb in that location has two filaments. One filament is bright and it is for your turn signals, 4-way hazard flashers and brake lights. The dim filament is for the park/tail lights. The lower bulb which corresponds with the clear square portion of your lens is the reverse light...only comes on when you shift to reverse with the key switched to 'on' as when the engine is running.
If you have a simple and cheap 12v incandescent test probe light, you can use it to easily diagnose a variety of electrical issues. If you don't have one, I highly recommend you get one at an early convenience. If you're going to own a Scout, you're going to have some electrical issues to suss out from time to time. It just comes with the territory.

 

[Booyah the monkey]

Okay, I still haven't been able to get the taillights or side marker lights to work the only lights that are working are the brake lights and panel lights. I cleaned off the grounds for the metal taillight housing but still nothing. I also noticed that the side marker lights are grounded directly to the body (pictures included), is that stock or was that done by somebody?

Also, I ran a 12v light on the wiring harness that comes from the front (picture included) and I get power from the inlet when the brakes are one but nothing from the inlet or the prong that comes out. It seems as if power should be coming from the prong that sticks out when I pull the light switch.

So I am stuck and not sure what to do next. I tried to replace the headlight switch but that did nothing.

 

[Booyah the monkey]

Okay, I've made a little more progress. I think the issue has something to do with the headlight switch. After I replaced it I got the marker and taillights to turn on when I pulled the know as far back as possible and I was able to turn them on and off a couple times. I left it and came back and now the marker lights and taillights won't turn back on. Any help is greatly appreciated.

 

[Scoutboy74]

Those grounds look fairly typical to me. Sounds like something May be wonky with your headlight switch. You should remove it for inspection of the connector plug and terminals. The plug May be loose or there May be corrosion interfering with a good connection. There is a spring-loaded button on the bottom surface of the hls. When you push it up as you pull on the knob, it will allow the knob to be removed from the switch. Then you can unscrew the dash bezel with a large, flat screwdriver and the hls can be worked down to where it hangs about even with the bottom of the dash. Then you can work the connector plug loose and have the switch out for a close inspection. If the blade terminals look tarnished or corroded, you should shine them up. If they're real bad, the corresponding connectors inside the molded plug will need attention also. Inspect the plug and associated wires for damage. When all is good there, pop everything back into place and see if there is any improvement. If that doesn't help, your switch May need to be replaced. They're fairly inexpensive and readily available.