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no brake lights or hazards

1K views 26 replies 3 participants last post by  14Sport 
#1 ·
I have a 92 yj originally a 2.5 5 speed, has been swapped over to a 4.0 aw4 combo from an xj with complete xj wiring harness. The issue im having is that i cant get my brake lights and hazard lights to work, can anyone point me in the right direction on where to start, maybe give me an idea where the ground wires could be? Thanks in advance for any help yall have
 
#6 ·
Iv determined that im not getting power to the brake pedal switch harness, i jumped the switch and the brake lights stay on steady but they also will eventually pop the fuse under the dash labeled gauges 7.5. Not really sure where the power to the brake pedal switch comes from?
 
#7 ·
Not familiar with Cherokees but page 8W-51-3 shows fuse 4 feeds the switch. But if you jumped the switch and the brake lights came on it indicates you are getting power to the switch. If they pop the fuse then it indicates they are drawing more power than the circuit is designed for. That circuit not only feeds the brake lamp but also the CHMSL and the license plate lamp so they are all suspect for a short or miswired.
 
#8 ·
How did you physically connect the YJ lights to the TJ harness? You may have your pinouts wrong. If you still have the old YJ harness I would cut the connectors off of that and replace the TJ connectors with them. Just make sure you get the pinouts right. Same with the brake switch although it looks like cruise control is the only difference there. The reverse lights on the YJ are also case grounded.
 

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#9 ·
I have the xj cherokee taillights hooked up and laying in the back, once i figure out how to get the brake lights operational im going to switch to 4" flush moumt leds, to clearify when i jump the brake switch i mean that iv ran a hot wire from the battery to the switch and the lights come on. The harness itself does not have power on any plugs when using a test ligjt or voltmeter
 
#10 ·
If you do not have 12V at the input side of the brake switch (pin 5) and fuse 4 is good then you have a break in the wire between the PDC and the brake switch or a poor connection. The schematic shows three connectors in that path (C151, C158, and C229). Make sure they're clean and tight and test for 12V at each to narrow down the problem wire.

The lights ground at G301 in the left rear quarter panel along with several other grounds. Are those connected to the tub?
 

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#14 ·
In my experience the turn signal switch presents itself differently. However, the hazard switch on the turn signal switch can create problems if it is sitting between the all the way in and the all the way out positions.

You never answered my question about the G301 connection.
 
#16 ·
1. Its an xj harness, 95 cherokee 4x4 4.0l aw4
2.yes swapped the entire harness (engine bay harness and both interior harnesses)
3.only has the xj harness
4.tail lights work
5.turn signals work
6.Did not pull the connector ran a wire from the battery to the back side of the connector where the brake switch connects to the harness. Not sure which pin number it was but it was the solid white wire. No other pins would illuminate the brake lamps
7.it would blow the fuse labeled 7.5 gauges under the dash only
8.yes and yes
 
#17 ·
Sounds like you may have been jumping it to the sense wire if it was white/pink. Since you have rear directionals, that rules out the socket and grounding at the tail lights since they share the same filament within the bulb. The taillights use a separate filament. Try disconnecting the brake switch and putting a jumper on the connector between pins 5 and 2. This will bypass the brake switch and test if you have power at pin 5 at the same time. Those would be the two center pins as shown on the top half of this page.



If that doesn't turn the brake lights on, then try applying 12V to pin 2 of the connector which is white/tan. That will bypass the brake switch and the 12V feed to it. If that works, then test pin 5 of the connector for 12V.

(I suspect the XJ had ABS and cruise control and you may have some issues with these wires coming into play. You may have to wait until Que gets back from his honeymoon.)
 
#20 ·
Sorry I keep deleting posts because the further I dig into it the more questions I come up with. For example, as I said fuse 4 feeds both the brake switch and the hazard section of the combination flasher. It is called the combination flasher because it is used for both the hazards and turn signals. So since your front hazards work it indicates that it is getting power from fuse 4. So then the assumption becomes, since it's a new hazard switch, that it must be the connector from the hazard to the rears lights. However, the wiring from the hazard switch to the rear lights is also shared by the turn signals which work. T'is a puzzlement. :dunno: I would still check for 12V at pin 5 of the brake switch.

Are you running a YJ or TJ turn signal/hazard switch? What about the PDC? Maybe it's just a pinout thing. I'm guessing the XJ fuse box so XJ relay center as well?
 

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#25 ·
Since you didn't have the pinouts and you're requesting them now I'm leaning toward a pinout error and it sounds like you are too.
 

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#26 ·
Okay just an update, i jumped pin 2/5 on the brake plug and got nothing, still no power on the plug at pin 5. Ran a hit wire from the battery to pin 5 and the ligjts illuminate. I pulled the hazard relay and checked for power on the fuse box and have no power on either side? Im really scratching my head at this point
 
#27 ·
I traced the path of the power coming from the battery to both the brake switch and the combination flasher with red lines. As you can see they are both fed by fuse 4 in the PDC. When you hit the brakes the stop lamp switch closes and connects circuit L9 to circuit L50 which I circled in purple. You should be getting 12V all the time at arrow number 3 (pin 5 of the stop lamp switch) and arrow number 2 (pin 2 of the combination flasher). If neither has 12V, then the problem lies before arrow number 4 in the circuit. Check fuse 4. If it is good, test that you are getting power at arrow number 1 with the fuse removed.

Now on the YJ the stop lamp switch is fed from fuse 3 of the fuse block which is fed from fuse 3 in the PDC. If you are using the YJ PDC you have to remap all your pins. I just pulled an XJ PDC from the JY last week. Took the bracket too and it still had all the fuses and relays for $35. I pulled the bottom off and removed all the pins with the intent off repining it as a aux box for my daughter's 1968 C10. So you should be able to repin yours the same way.
 

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