Turn signal / flasher issues

[ChristianR]

01 TJ Sport. I’ve had this Jeep for at least 15 years. Many upgrades.

I added rear LEDs, front leds, with the flasher relay that came with them. everything has work with no problem (for years). Had to change the MFS a year ago because the fog light switch was sticking in the on position and draining the battery. Changed it, no issues. Then the turn signals stopped working, flashers were fine. Bought a new MFS and nothing worked, though I got a bad one. 2nd one and same. I noticed the #13 fuse was popped and #7 was bad. Changed both and nothing. Turned flasher on and immediately popped both fuses. I’ve checked wiring and grounds, all appear good. I replaced the MFS harness (it was falling apart) and still nothing.

One strange thing. If I put the #13 in and leave #7 out when I turn the turn signals on they light up but don’t flash. Then if I turn flashers on it pops the fuse and same time the radio shuts off and then comes back on… that’s crazy.

Any ideas?!!!

 

[Chris]

01 TJ Sport. I’ve had this Jeep for at least 15 years. Many upgrades.

I added rear LEDs, front leds, with the flasher relay that came with them. everything has work with no problem (for years). Had to change the MFS a year ago because the fog light switch was sticking in the on position and draining the battery. Changed it, no issues. Then the turn signals stopped working, flashers were fine. Bought a new MFS and nothing worked, though I got a bad one. 2nd one and same. I noticed the #13 fuse was popped and #7 was bad. Changed both and nothing. Turned flasher on and immediately popped both fuses. I’ve checked wiring and grounds, all appear good. I replaced the MFS harness (it was falling apart) and still nothing.

One strange thing. If I put the #13 in and leave #7 out when I turn the turn signals on they light up but don’t flash. Then if I turn flashers on it pops the fuse and same time the radio shuts off and then comes back on… that’s crazy.

Any ideas?!!!

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From what you're describing, it seems like there's a short circuit somewhere in the system that’s causing those fuses to blow.

Here are a few things you might want to check:

Ground Connections: Even if you've checked the wiring and grounds, it might be worth going through them again. Electrical gremlins can sometimes hide in the smallest details. Make sure that all ground connections related to the lighting system are clean and secure.

LED Load: Since you’ve converted to LEDs, it’s possible that the flasher relay is not compatible with the type of load the LEDs present. If you haven't already, try replacing the flasher relay with one that's designed for LED lights.

Wiring Issues: Look for any frayed wires or damaged insulation, especially in areas that may have seen wear or corrosion over the years. It's possible that some wires are touching where they shouldn't be, causing the short.

Check for Water Intrusion: Water can cause all sorts of electrical problems in Jeeps. Make sure there’s no moisture in any of the connectors or the MFS.

Inspect the MFS: Since you've replaced the MFS twice, ensure that the new units are indeed compatible with your setup and that they aren't faulty. If possible, you might want to check them on another vehicle or try a different brand.

Fuses and Circuit: Since both #13 and #7 are blowing, you may need to trace the circuit for any other components that might be pulling too much current. Look at the possibility of a short in the wires leading to the taillights or the front turn signals.

Testing: As a last resort, you could isolate sections of the circuit to see where the problem might be. Try connecting the lights directly to the battery (with appropriate fuses and connections, of course) and see if they work without blowing fuses.

Keep us updated on your progress. Good luck!

 

[ChristianR]

From what you're describing, it seems like there's a short circuit somewhere in the system that’s causing those fuses to blow.

Here are a few things you might want to check:

Ground Connections: Even if you've checked the wiring and grounds, it might be worth going through them again. Electrical gremlins can sometimes hide in the smallest details. Make sure that all ground connections related to the lighting system are clean and secure.

LED Load: Since you’ve converted to LEDs, it’s possible that the flasher relay is not compatible with the type of load the LEDs present. If you haven't already, try replacing the flasher relay with one that's designed for LED lights.

Wiring Issues: Look for any frayed wires or damaged insulation, especially in areas that may have seen wear or corrosion over the years. It's possible that some wires are touching where they shouldn't be, causing the short.

Check for Water Intrusion: Water can cause all sorts of electrical problems in Jeeps. Make sure there’s no moisture in any of the connectors or the MFS.

Inspect the MFS: Since you've replaced the MFS twice, ensure that the new units are indeed compatible with your setup and that they aren't faulty. If possible, you might want to check them on another vehicle or try a different brand.

Fuses and Circuit: Since both #13 and #7 are blowing, you may need to trace the circuit for any other components that might be pulling too much current. Look at the possibility of a short in the wires leading to the taillights or the front turn signals.

Testing: As a last resort, you could isolate sections of the circuit to see where the problem might be. Try connecting the lights directly to the battery (with appropriate fuses and connections, of course) and see if they work without blowing fuses.

Keep us updated on your progress. Good luck!

Thanks for the tips. Some responses:
Water/Moisture - Highly unlikely - Park indoors and the top and doors have been off since last spring and only driving on nice sunny Texas heat days.
Relay: - I’ve ordered and tried 3 different LED relays - Two are in the pics.
MFS: - I’ve actually tried about 5 different switches - Just keep returning and getting a different one. I have two new ones right now. I just don’t believe that 5 MFS could be bad.

Grounding issue? The lights work fine when Turing head lights on but they won’t flash when the switch is on.

Still trying to figure out why when the #13 fuse behind glove box blows the radio will reset. Not of same fuse, why would that do that. It’ll basically turn the radio off and then it comes back on.

 

[hear]

In before somebody complains about crossover steering.

 

[ChristianR]

In before somebody complains about crossover steering.

Good eye, no complaints here.

 

[ChristianR]

So I bought a power probe and fixed the issue.

 

[hear]

Thanks for the details around what you tested, what you found, and how you fixed it. Future readers will hail this thread as a beacon in the night when it comes to resolving electrical issues in their beloved TJs.

 

[Mac57]

So I bought a power probe and fixed the issue.

Hey @ChristianR. Details? What did you test, what did you find, what did you do to fix it?