M715 project underway 305 chevy with 200-4R auto

[Blitz]

Good to know info about the breaker in the three way switch.

I have to wonder if , when towing a Military trailer at 24 volts lighting, if this is also an issue.

I would "think" that being 24 volts, less amps would be drawn through the switch.

either way,
If this ever happens to me, I will know where to look immediately.

So far, I have not hooked anything else up to the stock circuit. ( nor do I have any plans to , especially now )

The only thing I can think of is the electric 24 volt fuel pump that comes on when the master switch is on... and this is not the 3 way switch.

Just an interesting quirk with these trucks.



I have to wonder if everyone that has had this happen, has converted to 12 volts....
If I had enough coffee already, 12 volts will pull twice as many amps through the circuit.


Good info on the trailer brakes and front brake adjustments as well.

By the way Jeeper,
Good on Ya for fixing it on the side of the road.

I know that experience sucked.
I hear Ya , and can see it happening... 3 times.

[Blitz]

One last quick thought....

Since You are at a 12 volt system....

If You switched out to 12 volt LED's in Your lighting system....
Perhaps that would solve the issue and prevent forest fires.

The Headlights... I "think" will have to stay incandescent...
I dont think I've ever seen a LED headlight... but I live in a cave too.

EDIT:
I stand corrected:
LED Headlights
http://classicbroncos.com/forums/sho...d.php?t=158737

[jeeper]

One last quick thought....

Since You are at a 12 volt system....

If You switched out to 12 volt LED's in Your lighting system....
Perhaps that would solve the issue and prevent forest fires.

You are correct on the current draw being double at 12 volts. This is assuming I replaced all my 24 volt lamps with the same wattage 12 volt lamps. It also assumes a power factor of 1.


The equation is P=VxAxPF. P is power measured as Watts. V is electromotive force or Volts. A is amperage or current. PF is power factor.


If I switched out to LED lights I would likely reduce the load. But I would likely introduce another problem. I have an old school blinker relay in my truck. It works by thermal resistance. If I do end up with LED lights I will need to also install a solid state blinker relay to get the lamps to flash at a constant rate.

[Mikel]

Although putting a relay for the headlights may be a better solution than messing with the factory switch.

[jeeper]

Since the 3 lever switch in my latest M715 didn't work anyway I decided I'd take it apart to see how difficult it would be to clean/rebuild/upgrade the breaker. I found a pretty good write up about it here. The author suggested the possibility of bypassing the breaker and adding the fuse/breaker externally. An idea that I may pursue.

I took my switch apart and it is pretty bad. I am going to take some pictures. I have already cleaned it up a bit so the pictures won't show how bad it was when I started.

I will probably start a new build thread for the latest M715. This one will take quite a while to rebuild because it has major rust. I should probably just look for another cab but want the experience of the major body work required on this one. I hope I don't regret doing it.

[Blitz]

Thats an excellent write up.

Those are pretty complicated.

I can see now, why they develop more resistance over time and cause problems.
I sort of like the idea of an external mini fuse, that you can get to.
A relay also... its just bigger to hide

[Barrman]

I am glad to hear your 6.2 did good.

I think you might just have a bad three lever. I have pulled 24 volt trailers behind my 12 volt M715 with a stock 3-lever, 12 volt trailers behind my 24 volt M35's and never had the problem with the breaker popping.

Based on what others have shared over the years. Once the breaker pops, it will do so at less load the next time and then less the time after, etc..

[jeeper]

Based on what others have shared over the years. Once the breaker pops, it will do so at less load the next time and then less the time after, etc..

I'm just guessing here but that actually makes sense to me because the arcing that occurs when the breaker/thermal switch trips could cause some slight pitting on the contact points. When it cools down and resets there may be slightly more resistance in the circuit because of that?

I would think it may be similar to the way the points on an ignition need to be cleaned/replaced occasionally?

I will be adding some pictures to my other M715 build thread. I have already modified the three lever switch from that truck but don't have it re-assembled and tested yet.

[jeeper]

I ended up selling this truck today. It was a little sad. I am not too sad though because I still have an M715 to work on. And now I will probably be looking for a CJ or a Wrangler that the whole family can enjoy.

[jeeper]

I ended up getting a decent TJ and still have some money left over. I will be using some of that money left over to make a few repairs. My wife hasn't seen it yet.