sniper34639

I have searched the forums and all I couldn't find anyone with the same problems I don't know if I just couldn't find it or what.

Vehicle: 1987 Pickup 4x4 base model

Problem: when I have my truck's lights on either running or headlights all my taillights come on including the reverse lights, when I hit the brake with them on they're all still on but get dimmer, the left side taillight is a more drastic change then the right, and the turn signal indicators on the dash light up. when I put the left turn signal on it seems to work fine but when I hit the brakes the rear signal goes out. and there seem to be no issues to the front lights what so ever.

Stuff I tried: I've tried cleaning all the connections, replaced 3/4 of the wires I checked that where corroded or messed up (after I did that the brake bulb socket on the right rear melted), I have replaced all the sockets on the rear lights, and got new bulbs. I've literally went wire by wire from the cab back (found a cluster of hacked wires for the trailer lights), and even went thru the fuse box on the inside of the truck.

I don't know what else to do or try to get the problem resolved it just seems like I'm spinning my wheels or if I just have gremlins living in my lights.

thanks in advance for the help.

scope103

You probably have a broken ground somewhere. So when you power, say, the taillights, rather than returning directly to ground it goes through another bulb to ground.

I don't know about the '87, but the bed on my '94 is "insulated" from the frame, so the ground connection is through a separate wire. Connecting to the frame won't work.

This is a multimeter job. Don't have one? No excuse for that. http://www.harborfreight.com/7-funct...ter-90899.html

sniper34639

I have checked all the wires and grounds with my meter and everything appears to be correct according to the schematic I have and the readings. that's what is driving me insane.

I will go thru it all again with my meter and see if I missed anything it may be the same as your 94 I'm not sure but I will definitely try it to see if it is that. and will let you know what I figure out.

wyoming9

iTrader: (1)

Gremlins forsure!!

The sockets you replaced were they all new ??

Just because it tests for continuity( Meter probe makes good contact) does not mean the plug or the sockets are not corroded lots of times you can not see it with the naked eye.

Damage to the wires just how did you fix this ??

You are using the correct bulbs ??

Since these are a switched ground system you have a bad ground for sure !!What that means is the switch makes the ground completing the circuit

The ground is on the right fender .

Clean that up either it is making a poor connection or there is more physical damage you missed.

Maybe you made a poor connection some place.

RAD4Runner

Guys,
Headlight control is switched ground, but tails, markers, backup, and brake lights are not; switches provide positive signal when closed.

Yes, grounds like ^^^.

Plus, if ur reverse lights come on with tail lights, u must have a short between positive side of back up lights and positive side of taillights. Remove bulbs and check for continuity. There shud be none between the two, unless transmission is in reverse.
If dash turn indicators come on with ur brake lights must also be short between the two.
I suggest u do same check as above.
When tails dim while brake is depressed, this could be expected IF ur charging system or battery is weak
Problem with wiring make it worse.

wyoming9

iTrader: (1)

It was hot my brain slows down!!

sniper34639

Wyoming, I replaced them with new sockets, and I made sure they are the right bulbs, I soldered and put heat shrink on each connection, I will check everything again, and will check the ground on the fender.

Rad4runner, I will check that and I just put a new alternator/battery in it and did the fusible links like you showed other threads because mine was jimmy rigged. I also had to replace the whole lighting/wiper switch on the column because he old one would cut all my lights off going down the road randomly.

thank yall for the advice, I will post my result when I get it done.

wyoming9

iTrader: (1)

One of those things

Maybe you got some wires mixed up

I already soldered a Red wire to a green wire only to come back later and find it.

More physical Damage to the harness ??

RAD4Runner

Make sure you remove everything that's part of the trailer lights and that where they were tapped into smock wiring there is no corrosion, broken wire,shorting strands, worn insulation, etc.

AKHeathen

x2 i can't seem to keep a trailer wire adapter in mine. didn't check if it effected the tail lights visually, but it would certainly kick out cruise with the turn signal. i just wired up 4 relays to convert 5-4 trailer plug. this is oune of those times, i would say test with a meter, but also a test light. bring a power wire back and test the ground, and also read the resistance from the ground wire to ground, then swap the leads to reverse polarity and test resistance again. don't forget to zero the meter first and no more than .04 ohms

sniper34639

Ok so I pulled the entire rear harness out and put it on the meter everything works right, the ground on the fender was messed up so replaced it. When I started to move forward from where the harness connected in the cab I found 3 different wires in that harness under the passenger kick panel that had been cut, spliced, and reran. The white with a black stripe wire that according to the schematic I have is the ground for the entire rear harness, it was cut and taped off randomly on the side that connected back to the rear harness. I'm guessing one of the previous owners did it. I chased the wires back thru the truck and found where it was supposed to be connected to the other end of that wire was rigged into the radio along with about 6 other random wires. So I cleaned up the rat's nest of wires ran it back as "stock" as I could and now there are no issues with the lights work correctly, the dash indicators don't come on, and the radio even works now. I also did a good connection on the other wires that had been cut into, I also put wired in a trailer light connection off of main feed wires running to the rear how the factory connections would have been. Soldered and heatshinked all the connections and ran wire cover to help keep it dry and clean. As of now my trucks gremlins appear to be gone.


thank yall for all the help and advice it helped out a lot with the troubleshooting.

AKHeathen

glad you got it sorted.

Terrys87

iTrader: (1)

You are correct about the white wire with a black stripe is ground. Stereos and trailer wiring is the most hacked wiring I see on these trucks.

I see you already got the problem corrected, but there is a divider inside the lense that helps seperate the lights when glowing. I see them missing as well.

Thanks for letting us know you got the problem fixed. Welcome to Yotatech.

sniper34639

Terry the way the previous owners hacked up the wiring was insane I have never ran into so many problems with vehicle wiring in my life, the way the radio was wired in the stock plug was cut off and the new radio wires where spliced into it with the original plug on the other end of the hack job, you read above about the tail lights, the under hood fuse box was basically none existent I mean it was still bolted to the fender but half of the fuses and relays and such where just dangling. and not to mention the was they hacked up the ignition to put a toggle starting switch, so far I have got it mostly rewired back to stock and correct for that matter, and I have about 50 feet of extra wire that I have removed from it. It's been a pain but its running right (knock on wood) and seem to be like the issues are solved.

RAD4Runner

Glad u figure it out. Restoring to stock is the way to go.