Trailer Causing Curcuit Breaker Problems

[SasquatchSanta]

A few weeks ago we installed (wired) a trailer brake unit that allows me to pull my 18 foot McLander trailer behind the deuce. After contacting the tech support department of McLander and the manufacturer of the brake controller we arrived at a way to use a relay to run the electric trailer brakes on 12 volts. We changed the trailer lighte over to 24 volt bulbs and everything worked fine --- or at least we thought.

The lights and brakes all checked out and worked fine BUT at night, when all the lights are on it's not uncommon for a circuit breaker to blow when the turn signals are turned on. When it happens everything goes black. If a wait a few seconds and turn the switch off and then back on again the lights will come back on.

I doesn't have anything to do with the brakes. I can turn the brake controller off and the problem still happens. I think the added draw from the lights on the trailer are limiting out the curcuit breaker. I should note that I've also added 5 top of cab clearance lights that are also drawing from the system.

I had a similar problem back when I first installed the electric radiator fan. When I wired it direct to the batteries the problem went away. I can't wire around the trailer lights so I'm wondering if the circuit breaker could be changed. Problem is --- I can't find the damned thing.

Where do I look to find the circuit breaker?

Anyone got any suggestions?

 

[rsh253]

I'm having a similar problem with my deuce: I'm losing all the lights when I use the turn indicator. I must have a short to ground somewhere, like you, but I haven't found it yet. The only circuit breaker I've seen refered to in the TMs or wiring diagams is the one for the horn. I just found this this thread, however, and there's a CB in the light switch. That would explain why the lights go out & then come back on. You might want to look at TM 9-230-09--1 Fig 5-18 for a trouble shootiing proceedure. That's what I'm going to try next.

Good luck. Pls let me know what yu find.

-Russ


http://www.steelsoldiers.com/index....e=viewtopic&t=19703&highlight=circuit+breaker

 

[rsh253]

Sorry. My typing skills are worse than my electrical trouble shooting skills.

TM 9-2320-209-20-2-1
Fig. 25-18

 

[rsh253]

Did some more looking at the TM. Fig 25-20 might be a better starting point than 25-18.

 

[cranetruck]

Check my relay posts for the solution, diagrams and images have been posted throughout the last couple of years, including manual override for the headlights....

 

[jwaller]

they are usually on the firewall right next to the steering column.

 

[Floridianson]

Right engine firewall steering column.
Russ don't know could you take the head lights out of the equation as they draw the most. If it a short it will still do it with or with out the head lights on.
Put main switch on service drive and auxiliary switch on park. I think your blinkers will still work but the head lights will be off and see if the CB holds.

 

[rmgill]

You could get some dual voltage or single voltage LED's for the trailer to reduce the draw. I'd also make sure the trailer has a GOOD solid ground going back to the truck. If it does not, it could be causing problems.

Did you pull the brake controller's power from the Lighting Circuit? If so, that's going to be your problem.

Total voltage draw with the truck, accessory lights and the trailer lights could be your problem. Running some relays for the headlights would be a good first step. Then add some LED lights to minimize current draw. Then think about adding relays for the other lights. That's more complicated for the additional lighting circuits and requires more cutting. You can run A Relay for the headlights easily with minimal mods and cutting of the existing harness.

 

[rsh253]

Guys,

Just to clairify: a stock M35A2 cargo deuce would have just one circuit breaker on the firewall and that would be for the horn circuit? (I saw on one circuit diagram that the tractor has a seperate CB for aux. power; and there is a CB for the cab heater if there's one.) The curcuit breaker that is blowing for Ernie & me is the one inside the turn signal unit?

James,

I tried your experiment and it was very helpful. The CB pops as soon as I activate the turn signals, even with the headlights off; so I think that indicates a short rather than over-load(?). My electical system was working fine one day, and kaput the next. The CB pops whenever I activate the TS. That, and the wiring being old and having bad insulation, is why I suspect I have a short.

-Russ

 

[rmgill]

The Lighting control switch (the three lever switch) has a breaker built in.

 

[Recovry4x4]

If you scroll back up and take Bjorn's advice, you will find not only the answer to the questions but also the solution. He has covered this quite well in many previous posts and it takes too long to type it all over again. Even the headlight draw can be taken off that breaker as suggested, Bjorn already did it.

 

[SasquatchSanta]

Thanks all for the input.

I was hoping the circuit breaker was seperate from the light switch. Given that it's only 20 amp I can see why I have a problem.

The trailer brakes are already seperate from the lights so it looks like I need to segregate some load off the switch. I originally considered LED lighting for the trailer but didn't want to invest that kind of $$$ for something I use so very little.

I'll research Bjorn's posts.

Thanks again.

 

[Desert Deuce]

Bjorn's solutions and engineering regarding this issue are spot on. I've had this problem as well with my Lube trailer. There are lots of lights on a lube trailer.

 

[rsh253]

Well, after a very frustrating day & 1/2 I finally have my turn signal flasher problem figured out.

The TS stopped working several weeks ago & after much testing I felt pretty confident I had a bad flasher unit. I ordered a new flasher and installed it. The TS still did not work, but now when I tried to use them, my CB tripped! I figured I had a short somewhere. I disconnected each light housing, the CB still tripped, then disconnected the various circuits from the TS switch, the CB still tripped. Took the TS switch apart 3 times looking for a short or some other problem, the CB still tripped. I covered the wiring harnesses with electric tape in case I had a break in the insulation, the CB still tripped.

While laying in bed last night, I suddenly realized that the CB didn't start to trip until after I installed the new flasher unit. This morning I put the old flasher back in, and now the CB doesn't trip! The TS still don't work, but the new flasher unit was bad and was shorting to ground and that was the cause of the CB tripping. I can even get the lights to blink by shorting between the A & B terminals on the plug to the flasher unit.

Tomorrow morning I'll be ordering a second replacement flasher unit. What a way to spend the day!

-Russ