Lights Going Bananas - My current headache.

[Shittymorph]

Hello everyone! My name is Chris... and I have a 1984 Toyota Rader with a 22r... right around 100k miles and in mostly clean original condition. Recently, I moved into an apartment where I am only allowed one car - since I owned both an Outback and this Toyota rig... the Outback had to go. That makes this my daily driver... which is ok by me... except right now my tail lights are going haywire and I can't figure them out. I have pulled every single bulb one by one... I have inserted each bulb one by one... I have disconnected the lights in the front. I saw some wear on the wiring harness going to front headlights and changed those out. Still... can't shake this ghost. Please see attached GIF below for exactly what is going on. 

 

When I hit the brakes the rear end lights up funny. If I leave the marker lights in (they are removed in the video) they also light up randomly like a christmas tree. I have tried all new bulbs TWICE like an idiot... I have removed the housing from both the left and right side rear lights - and all the connections seem properly daisy chained together with no obvious errors. I am at a loss on how to find this ghost and fix it. Any ideas would be greatly appreciated! Thank you in advance! - Chris

 

Edit - a couple of other minor notes. The lights on the back left look more dim that the lights on the back right. Reverse lights do not seem to be functioning at all right now. Using left turn signal clicks more slowly than the right turn does at the dash. I have replaced the relay that controls that to no avail. Front end lights work fine. If the headlights are turned off... the rear lights work as they should... when the front headlights are on... they go haywire like you see in the GIF. Could it be switch on steering column? Anyway... thank you for your consideration of my issue.

Edited September 25, 2025 by Shittymorph
Further clarification

[extech]

definitely bad grounds at the tail lights 

[Shittymorph]

Any advice on chasing this down? I picked up a multi-meter but not really sure on where to start with it. Thank you for your time. 

[extech]

multimeter  neg lead to a good ground.   shiny metal.  pos lead to the neg connection for the light- usually a screw into the body. 

  if the meter shows voltage, there is no connection there.  tighten the screw untill meter shows 0 v 

[Shittymorph]

Yea just need to find where that is. I have tracked the line from the front to the rear and no obvious breaks all wrapped neatly in electrical tape. Im guessing it's one of the 2 prong connectors in the light housing. The ground from the battery goes to the front fender and everything seems to charge. I feel like a bit of an idiot with regards to this stuff - but I have tools and hope to solve it myself. Will try the multimeter tests tomorrow. Thank you for your input... I am grateful. 

[fred heath]

Most MH manufacturers extended the original truck rear harness to accommodate the extra length.

 

Locate the factory harness under the truck and follow it until you find the splice for the extension. Many times they used crimp butt connectors for the splice, then wrap the area with tape. Over time these connectors can lose their contact. Check everything, and replace or upgrade while you’re there.

 

Bad ground is also possible. The fact your front lights seem to be fine, I’d definitely check the rear harness.

Follow the harness into the coach itself. There could be some wear areas that are allowing a short to occur.

 

Good Luck.

Edited September 26, 2025 by fred heath

[Shittymorph]

Hello everyone, I wanted to stop back by to this thread and let folks know it was indeed bad wiring in the rear. Sort of a "No crap bad wiring" moment - but a friend and I dug into it and basically rewired, soldered, taped, zip tie all new wires. I elected to keep the old style tail lights even though upgrading to LED might have made sense...  my rig is 99% original from factory and I'm going to try to keep it that way. Part of the reason why I didn't upgrade the interior - to keep a time capsule intact. There was one connector in particular which was corroded... also one bulb socket had managed to spin around inside the housing which caused a short there. A couple issues were found - all back to normal now. Thanks for the help everyone who commented. I am grateful for the guidance.