Tail light issue

[Asmith29]

This is my first post, so be gentle please. My M998 electrical system seems to work fine, but when I turn on the service drive lights, the headlights, marker lights, turn signals and brake lights work just fine, but the tail lights do not come on. Any suggestions? Thanks,
AO

 

[Dock Rocker]

Have you checked to see if the bulbs ar blown?

If the bulbs are good clean the ground wire at the tail light itself. Each one has its own ground wire.


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[Asmith29]

Bulbs are good, brake light and turn signals work, just not running tail light. Will check grounds individually.

 

[wheelspinner]

Just because the brake/turn work does not mean the tail light bulbs are good.

 

[spoonsc1]

I recently had some crazy light issues, blinkers barely noticeable intensity with headlights on, light in the turn signal was barely visible with headlights on, all kinds of things. what I found throughout all the troubleshooting was the blinker switch was a problem since almost everything runs through it. the switch may say solid state on it, but "DONT YOU BELIEVE IT......." remove the bulb from the switch and take the screws out and take it apart, it is all dry contacts on a cam, nothing solid state at all. I used emery cloth between the contacts and cleaned them all well. this brought all the lights back to full intensity and flashers worked as advertised. free to check and fix, may be the issue for you.

 

[papakb]

spoonsc1, the electronic master light switches do have their own gremlins that can cause all kinds of problems with the electrical system. If the switch in your truck doesn't have the ground lead securely connected they tend to self destruct in strange ways. If you don't have the supplemental ground harness installed you should do yourself a favor and install one. They're easy enough to build with the directions found here on SS and available online.

The turn signal switch has it's own set of issues, most of them being due to tarnished contacts as you found out. Great that you found your issues!

 

[spoonsc1]

papakb, appreciate the input, although I was merely giving an experience I had to possibly aid Asmith29 with his issues. I also recommend a supplemental ground harness, I installed a manufactured one but yes, easily locally manned. when you rivet a bunch of crushed beer cans together corrosion can make grounding a challenge!!

 

[juanprado]

Just because the brake/turn work does not mean the tail light bulbs are good.

This a great tip as the bulbs have dual elements just like your civy car.

 

[Action]

This a great tip as the bulbs have dual elements just like your civy car.

Are you sure? Have you looked in your taillight?

 

[papakb]

Yeah, mine all have little square LEDs in them..........................

 

[Asmith29]

Tail light issue continued

Another question for you pros out there. I finally got my M998 registered here in the Commonwealth of Virginia (as a SUV), and am trying to install the lighted rear license plate bracket that I got from Those Military Guys. Two questions, first it came with 4 self tapping screws. I assume I drill those directly into the frame to mount the light (I'm putting it to the left of the tow pintle) correct? Just drill them in?

Second, on the YouTube video showing how to install this is says to intercept the 21 cable. I have found the wiring harness as described in the video but cannot find any of the cables marked as 21. There is a 21C, and several other numbered cables, but no 21. Could the main power cable be marked other than 21?

Tomorrow I take on the back up light, so be assured I'll be back asking the forum's help again.

Thanks

ASmith29

 

[papakb]

The number 21 is the designation for the running light signal, the letters are just the designations for the individual lamps that it connects to. You might want to pick up 21D on pin E of the trailer receptacle since it's right there.

Unless you have an ambulance your probably going to have to drop the shifter and add a switch to pick up the reverse light. There's already a hole there for it and if you make up a simple size reducing bushing the easiest thing is to just use a neutral start switch for it. I picked up power for mine from the lights in the shifter lighting thinking if I didn't want them to come on I'd just leave the instrument lights off and if I wanted them I'd put the master light switch to panel bright. Most of the original military reverse lights suck so I'd recommend a couple of nice 10-30v LED lights.

 

[Asmith29]

Thanks for the info. I finally found the 21 and discovered there is no power going through it, hence now I know why my tail lights aren't working while my brake and turn signals are.

 

[Asmith29]

Anyone know why the 21 cable may not have power? It's the wire to the rear service lights.

 

[porkysplace]

This is your 3rd thread on your tail lights , you should continue with your original thread and keep all the information in 1 place . It's also in the rules you agreed to .

• Do not Cross-post multiple posts or threads about the same topic. This includes either creating multiple threads about the same topic in multiple forums or the same thread repeatedly or posting the same post within multiple existing threads.

Tail light issue continued

Started by Asmith29, Yesterday 18:05

Tail light issue

Started by Asmith29, 07-21-2018 13:28

Moved by Mod to one tread.

 

[Action]

You probably don't have the light switch in the correct position...
brake lights and turn signals work in the first position.