Troubleshooting Your Jeep YJ Turn / Hazard / Brake Light Systems

I would cut it a few inches away from that connector so that you could splice back to it someday if needed.

Or even cut it on the steering column side so you aren’t permanently changing the factory harness.
 
machoheadgames...Excellent thank's again..!
I did a quick mock-up,cut the wire, ran a wire to back light.
All lights are working perfect.
Like you said no license plate light. There is a pop out cover on the bottom of the light fixture and
it didn't come with a clear lens.So I will buy an led spot for the license plate light.

Cheers..Thanks again.

IMG_2303.JPG
 
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Good to hear. I really wish one of the companies making LEDs for these would build an amber section into them. I would totally do the rewiring for that to happen, would be killer. I asked quadratec and rugged ridge if they would be interested but no one ever got back to me. My LEDs have 16 LEDs in 4 rows, would be cool if one row was amber instead. Oh well.
 
Totally agree..!
I was looking for LED's before a bought these and I had no luck...!
But I thought I will keep it original.
 
If you own a Jeep YJ, at the time of this writing it is at least 24 years old. That’s a long time for a rig that was designed in the early 80s, when the American automotive industry was, frankly, not doing its best work. If you’re going to keep your YJ working reliably, you’re going to need to give it some love. The lighting systems are common failure points on this rig. In this article, we’ll look at how to get the turn/hazard/brake systems working and keep them that way.


System Overview
The systems we’re looking at are powered from three fuses in the Power Distribution Center under the hood:
  • Fuse 3: 50 Amp, Fuse Block
  • Fuse 4: 40 Amp, Ignition System
  • Fuse 5: 20 Amp, Hazard Flash
Aside from the Power Distribution Center, the major components in the systems are:
  • The Fuse Block (Figure 1), located under the dashboard on the left side of the rig.
  • The Ignition Switch, located on top of the steering column
  • The Stop Lamp Switch, mounted on the brake pedal arm
  • The Turn Signal and Hazard Flashers, located at the top of the fuse block
  • The Turn Signal and Hazard Flasher Switch, mounted in the steering column
  • The lights themselves, mounted at the front and rear of the rig, and also in the instrument panel
Aside from these, there are several connectors, with the main one being C218, the connector for the Turn Signal and Hazard Flasher Switch, located on the right side of the steering column.


Supply Power Checks
There are three checks to ensure that the systems are properly powered:

First, remove both flashers from their sockets in the fuse block. The left flasher is for the hazard circuit, and the right flasher is for the turn signals (see Figure 1). Each socket has two connectors arranged in a “V” pattern.
  • For the hazard (left) flasher socket, the left connector should be energized all the time
  • For the turn signal (right) flasher socket, the left connector should be energized when the ignition switch is turned on.
The Pink/Dark Blue wire connected to the Stop Lamp Switch should be energized all the time. While you’re there, confirm that the Stop Lamp Switch is working correctly by depressing the brake pedal and checking that the White/Tan wire(s) become energized.

Visually inspect the flashers before you put them back in. If either the turn or hazard systems are not working, you can swap flashers and see if that changes which system is failing. If there’s any reason to suspect the flashers, it doesn’t hurt to replace them.

Note: Fuse 3 is labeled “Haz Stop”, but does not protect or control the hazard circuit.

View attachment 115633

Figure 1: The Fuse Block


Supply Power Fixes
If your rig fails one of the power supply checks, the fix is to trace the circuit back to the power source (the battery), and find the component that’s causing the fault. We can reference FIGURE 2 to see what components need checking:

View attachment 115632

Figure 2: The Turn, Hazard and Brake Light Power Circuits
  • The hazard circuit feeds through Connector C114, directly from Fuse 5 (20 Amp) in the Power Distribution Panel.
  • The turn signal circuit feeds through Fuse 4 (15 Amp) in the Fuse Block, the Ignition Switch, Connector 114, and finally through Fuse 4 (40 Amp) in the Power Distribution Panel
  • The brake light circuit feeds from Fuse 3 (15 Amp) in the Fuse Block, through Connector 114 and then Fuse 3 (50 Amp) in the Power Distribution Panel
Pull the fuses and inspect them. It’s usually pretty obvious when a fuse is blown, but I have seen fuses that looked ok but were defective. Don’t overlook the connectors, both in-line and at various components; they are potential failure points. Sometimes simply unplugging a connector and plugging it back in can clean the contacts enough to get things working again. The connector at the turn signal switch is particularly vulnerable to issues due to wear, heat and over-current problems (Figure 3). Look it over for loose or broken wires or anything that looks burned or out of place.

View attachment 115631

Figure 3: The Turn Signal Switch Connector


It’s Probably A Bad Ground
There’s good reason why you hear that phrase a lot when you’re dealing with electrical issues, and especially when it concerns old lighting systems. Using the vehicle chassis as the ground system saves a huge amount of cost and complication, but it does introduce this one issue: There are going to be potential trouble points all over the rig, and any one of them can cause a system failure. Let’s look at some common culprits…
  • Sheet metal screw ground points. These can corrode, work loose, or the crimp connectors can fail. Keep them clean and tight.
  • Component mount points. Some parts such as the YJ tail light housings bolt to the body, and that bolted connection is also a ground path. Tight and clean are the key words here as well.
  • Bulb sockets (Figure 4). This is a very common failure point on older vehicles, and it can cause weird problems where various circuits start to interact (i.e. you put on your left blinker and your tail lights dim). What’s happening is a circuit has lost its regular path to ground, and is grounding through another circuit. Often, the connection point is a shared bulb socket that gets corroded, so the problem shows up a lot with the turn/stop and tail light circuits.
If you are dealing with lighting issues, one of the first and most important things you can do is pull the light bulbs, inspect and clean the bulbs and sockets, replace anything that looks like it needs it, and put everything back together with dielectric grease.

Note: Bulbs that are corroded into their sockets like to shatter rather than come out when you try to pull them. Wear gloves!


View attachment 115629

Figure 4: The bulbs and bulb sockets in a yj weren't awesome when they were new. Age and moisture only make them worse..


Is it the Switch?
If things still aren’t working once everything is cleaned up, it’s time to figure out if the problem is the turn signal switch. By looking at FIGURE 5, we can trace the path of the current through the switch under the different circumstances.

View attachment 115630

Figure 5: The Turn Signal Switch


Brake Lights
When the turn and hazard switches are both “off”, brake light current passes directly through the turn signal switch. The input is the White/Tan wire that we checked earlier. It should be energized when the brake pedal is depressed. The output wires are:
  • Left Turn (rear): Dark Green/Red
  • Right Turn (rear): Brown/Red
Both of those wires should be energized when the brake pedal is depressed.


Hazard Lights
The input wire for the hazard circuit is Pink. It is fed directly from the Power Distribution Center under the hood, through the hazard flasher. When the hazard switch is on, the following wires should have current in an intermittent, flashing pattern:
  • Left Turn (rear): Dark Green/Red
  • Right Turn (rear): Brown/Red
  • Left Turn (front): Light Green
  • Right Turn (Front): Tan
Note that the two front circuits also branch off to feed the turn indicators on the dash.


Turn Signals
The left and right turn signal switches defeat the stop light circuit for that side, allowing the other side to continue to act as a regular stop light while the active side is indicating a turn. The wires for the front and rear turn circuits are the same as for the hazard circuit. The front and rear circuits are on separate contacts in the switch, so it’s possible for one end of the rig to be working, while the other is not.

Below is the information for the various circuits, and a “truth chart” for the various functions. It’s good to check the turn signal switch thoroughly before deciding to replace it, but frankly, if you’ve gotten this far in the testing, it’s probably a bad switch.

Connector Terminal #Wire ColorDescriptionStop OnHazard OnLeft TurnRight Turn
1White / TanStop V+ (From Brake Switch)
2Brown / RedRight Rear Turn / StopV+V+ FlashV+ Flash
3Dark Green / RedLeft Rear Turn / StopV+V+ FlashV+ Flash
4Red / WhiteTurn Signal V+ (Ignition Switched/ From Flasher)
5PinkHazard V+ (From Flasher)
6TanRight Front Turn & Dash IndicatorV+ FlashV+ Flash
7Light GreenLeft Front Turn & Dash IndicatorV+ FlashV+ Flash


Other Things to Check
The likely causes are checked now. The rest are long shots.

The wiring harness for the rear lights runs along the left side of the rig, under the driver’s door and up along the left bed sill. From there it dives into the left rear fender area to feed the left rear lights, and then runs to the right side between the bed and fuel tank. There are one or two connectors under the dash just in front of the driver’s door that feed that harness.

The front lighting harness also runs along the left side of the rig, coming through the main connector behind the fuse block at the firewall. If you’ve gotten this far, that connector is worth checking. Have some dielectric grease handy for putting it back together.

Wires can get pinched between metal components, cut on sharp edges, or cracked and brittle from heat or age. Sometimes a short in one circuit can cause wires in a harness to fuse together and short out. At this point the problem should be narrowed down to a specific circuit (rear left, etc). You may need to unwrap the harness and visually inspect the wires.

That’s all I’ve got. Good luck!

-Walt
This is awesome. My issue on my 88 yj is. I’ve got running lights in rear and front. I have both L/R signal in front and left signal and brake in rear. BUT no brake or signal on R/R and can’t seem to find out why. This all occurred after a trip to suspension shop for bushings
 
If you own a Jeep YJ, at the time of this writing it is at least 24 years old. That’s a long time for a rig that was designed in the early 80s, when the American automotive industry was, frankly, not doing its best work. If you’re going to keep your YJ working reliably, you’re going to need to give it some love. The lighting systems are common failure points on this rig. In this article, we’ll look at how to get the turn/hazard/brake systems working and keep them that way.


System Overview
The systems we’re looking at are powered from three fuses in the Power Distribution Center under the hood:
  • Fuse 3: 50 Amp, Fuse Block
  • Fuse 4: 40 Amp, Ignition System
  • Fuse 5: 20 Amp, Hazard Flash
Aside from the Power Distribution Center, the major components in the systems are:
  • The Fuse Block (Figure 1), located under the dashboard on the left side of the rig.
  • The Ignition Switch, located on top of the steering column
  • The Stop Lamp Switch, mounted on the brake pedal arm
  • The Turn Signal and Hazard Flashers, located at the top of the fuse block
  • The Turn Signal and Hazard Flasher Switch, mounted in the steering column
  • The lights themselves, mounted at the front and rear of the rig, and also in the instrument panel
Aside from these, there are several connectors, with the main one being C218, the connector for the Turn Signal and Hazard Flasher Switch, located on the right side of the steering column.


Supply Power Checks
There are three checks to ensure that the systems are properly powered:

First, remove both flashers from their sockets in the fuse block. The left flasher is for the hazard circuit, and the right flasher is for the turn signals (see Figure 1). Each socket has two connectors arranged in a “V” pattern.
  • For the hazard (left) flasher socket, the left connector should be energized all the time
  • For the turn signal (right) flasher socket, the left connector should be energized when the ignition switch is turned on.
The Pink/Dark Blue wire connected to the Stop Lamp Switch should be energized all the time. While you’re there, confirm that the Stop Lamp Switch is working correctly by depressing the brake pedal and checking that the White/Tan wire(s) become energized.

Visually inspect the flashers before you put them back in. If either the turn or hazard systems are not working, you can swap flashers and see if that changes which system is failing. If there’s any reason to suspect the flashers, it doesn’t hurt to replace them.

Note: Fuse 3 is labeled “Haz Stop”, but does not protect or control the hazard circuit.

View attachment 115633

Figure 1: The Fuse Block


Supply Power Fixes
If your rig fails one of the power supply checks, the fix is to trace the circuit back to the power source (the battery), and find the component that’s causing the fault. We can reference FIGURE 2 to see what components need checking:

View attachment 115632

Figure 2: The Turn, Hazard and Brake Light Power Circuits
  • The hazard circuit feeds through Connector C114, directly from Fuse 5 (20 Amp) in the Power Distribution Panel.
  • The turn signal circuit feeds through Fuse 4 (15 Amp) in the Fuse Block, the Ignition Switch, Connector 114, and finally through Fuse 4 (40 Amp) in the Power Distribution Panel
  • The brake light circuit feeds from Fuse 3 (15 Amp) in the Fuse Block, through Connector 114 and then Fuse 3 (50 Amp) in the Power Distribution Panel
Pull the fuses and inspect them. It’s usually pretty obvious when a fuse is blown, but I have seen fuses that looked ok but were defective. Don’t overlook the connectors, both in-line and at various components; they are potential failure points. Sometimes simply unplugging a connector and plugging it back in can clean the contacts enough to get things working again. The connector at the turn signal switch is particularly vulnerable to issues due to wear, heat and over-current problems (Figure 3). Look it over for loose or broken wires or anything that looks burned or out of place.

View attachment 115631

Figure 3: The Turn Signal Switch Connector


It’s Probably A Bad Ground
There’s good reason why you hear that phrase a lot when you’re dealing with electrical issues, and especially when it concerns old lighting systems. Using the vehicle chassis as the ground system saves a huge amount of cost and complication, but it does introduce this one issue: There are going to be potential trouble points all over the rig, and any one of them can cause a system failure. Let’s look at some common culprits…
  • Sheet metal screw ground points. These can corrode, work loose, or the crimp connectors can fail. Keep them clean and tight.
  • Component mount points. Some parts such as the YJ tail light housings bolt to the body, and that bolted connection is also a ground path. Tight and clean are the key words here as well.
  • Bulb sockets (Figure 4). This is a very common failure point on older vehicles, and it can cause weird problems where various circuits start to interact (i.e. you put on your left blinker and your tail lights dim). What’s happening is a circuit has lost its regular path to ground, and is grounding through another circuit. Often, the connection point is a shared bulb socket that gets corroded, so the problem shows up a lot with the turn/stop and tail light circuits.
If you are dealing with lighting issues, one of the first and most important things you can do is pull the light bulbs, inspect and clean the bulbs and sockets, replace anything that looks like it needs it, and put everything back together with dielectric grease.

Note: Bulbs that are corroded into their sockets like to shatter rather than come out when you try to pull them. Wear gloves!


View attachment 115629

Figure 4: The bulbs and bulb sockets in a yj weren't awesome when they were new. Age and moisture only make them worse..


Is it the Switch?
If things still aren’t working once everything is cleaned up, it’s time to figure out if the problem is the turn signal switch. By looking at FIGURE 5, we can trace the path of the current through the switch under the different circumstances.

View attachment 115630

Figure 5: The Turn Signal Switch


Brake Lights
When the turn and hazard switches are both “off”, brake light current passes directly through the turn signal switch. The input is the White/Tan wire that we checked earlier. It should be energized when the brake pedal is depressed. The output wires are:
  • Left Turn (rear): Dark Green/Red
  • Right Turn (rear): Brown/Red
Both of those wires should be energized when the brake pedal is depressed.


Hazard Lights
The input wire for the hazard circuit is Pink. It is fed directly from the Power Distribution Center under the hood, through the hazard flasher. When the hazard switch is on, the following wires should have current in an intermittent, flashing pattern:
  • Left Turn (rear): Dark Green/Red
  • Right Turn (rear): Brown/Red
  • Left Turn (front): Light Green
  • Right Turn (Front): Tan
Note that the two front circuits also branch off to feed the turn indicators on the dash.


Turn Signals
The left and right turn signal switches defeat the stop light circuit for that side, allowing the other side to continue to act as a regular stop light while the active side is indicating a turn. The wires for the front and rear turn circuits are the same as for the hazard circuit. The front and rear circuits are on separate contacts in the switch, so it’s possible for one end of the rig to be working, while the other is not.

Below is the information for the various circuits, and a “truth chart” for the various functions. It’s good to check the turn signal switch thoroughly before deciding to replace it, but frankly, if you’ve gotten this far in the testing, it’s probably a bad switch.

Connector Terminal #Wire ColorDescriptionStop OnHazard OnLeft TurnRight Turn
1White / TanStop V+ (From Brake Switch)
2Brown / RedRight Rear Turn / StopV+V+ FlashV+ Flash
3Dark Green / RedLeft Rear Turn / StopV+V+ FlashV+ Flash
4Red / WhiteTurn Signal V+ (Ignition Switched/ From Flasher)
5PinkHazard V+ (From Flasher)
6TanRight Front Turn & Dash IndicatorV+ FlashV+ Flash
7Light GreenLeft Front Turn & Dash IndicatorV+ FlashV+ Flash


Other Things to Check
The likely causes are checked now. The rest are long shots.

The wiring harness for the rear lights runs along the left side of the rig, under the driver’s door and up along the left bed sill. From there it dives into the left rear fender area to feed the left rear lights, and then runs to the right side between the bed and fuel tank. There are one or two connectors under the dash just in front of the driver’s door that feed that harness.

The front lighting harness also runs along the left side of the rig, coming through the main connector behind the fuse block at the firewall. If you’ve gotten this far, that connector is worth checking. Have some dielectric grease handy for putting it back together.

Wires can get pinched between metal components, cut on sharp edges, or cracked and brittle from heat or age. Sometimes a short in one circuit can cause wires in a harness to fuse together and short out. At this point the problem should be narrowed down to a specific circuit (rear left, etc). You may need to unwrap the harness and visually inspect the wires.

That’s all I’ve got. Good luck!

-Walt
Any idea why my headlights, brake lights, turn signals all work but my tail lights do not?
 
Mine is having 3rd brake light not working. I know the lights are good and the contacts on door and body are good. But the power line has no power , does that connect to the brake light switch it self, would that be a bad brake light switch just trying to figure it out. Thanks
 
Mine is having 3rd brake light not working. I know the lights are good and the contacts on door and body are good. But the power line has no power , does that connect to the brake light switch it self, would that be a bad brake light switch just trying to figure it out. Thanks
Third brake light power wire comes straight from the brake light switch. The other two split from the brake light switch and go to the turn signal switch. If your two other brake lights work but the third doesn’t, then it’s not a switch problem, it’s a wire problem somewhere up the line.
 
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that a lot of very good information, as i have learned that the best$20.00 i every spend was to join the forum. i have saved so much money learning from other people, keep up the work. thanks
 
Third brake light power wire comes straight from the brake light switch. The other two split from the brake light switch and go to the turn signal switch. If your two other brake lights work but the third doesn’t, then it’s not a switch problem, it’s a wire problem somewhere up the line.
Trouble shot it today, found the white and tan wire in the harness buy the driver door , it had power, trac the harness back and found 3 Repairs buy the back piller where some one from u haul , as at sometime u haul had installed a trailer plug. That is where they had cut the 3rd brake wire for power to the trailer lights . What I found was really unacceptable work. But now fix as it should be and no more problems. Next on to the radio as you have to turn on the head lights to have the radio play. And while looking at that going to put in a radio with Bluetooth and other forms of media to play.but sadly not putting in Android Auto.
 
Trouble shot it today, found the white and tan wire in the harness buy the driver door , it had power, trac the harness back and found 3 Repairs buy the back piller where some one from u haul , as at sometime u haul had installed a trailer plug. That is where they had cut the 3rd brake wire for power to the trailer lights . What I found was really unacceptable work. But now fix as it should be and no more problems. Next on to the radio as you have to turn on the head lights to have the radio play. And while looking at that going to put in a radio with Bluetooth and other forms of media to play.but sadly not putting in Android Auto.
Well that’s a real shame, because a third brake light should have no relation to trailer wiring at all. Gotta love the poor work some do. Good luck on the rest of it.
 
Thanks , with these few very few problems it's in great condition, it's my baby now and going to put in and fix it to my standards. But the wiring schematics help a lot . Thank for getting back with me.