Current draw from batteries with Master switch off

[TommyG45]

Guys,

My deuce was sitting for a few days, and I noticed it didn't have a lot of crank left in the 6tls.

It did start, I let it run for a few minutes ~ 15 or so.

Couple of days later, no crank. I have since charged both batteries, 12 volts at a time.

When I connected the batteries up, I drew a little spark, I know the accessory switch was off, but something is drawing current.

This time I have disconnected the ground on the 12V pair until I have proper paperwork to drive it on the road and let it get a good charge. The 24V generator puts out strong based on the volt meter in the cab.

With everything off, is there something in the deuce supposed to draw current?

Until I can drive it, I will keep the batteries disconnected.

Thoughts or suggestions?

Thanks

TG

 

[doghead]

Are your gauge lights on? If not, I would suspect a bad alternator as a possibility. Disconnect it(both wires) and see if it still draws when you connect the battery cables.

 

[bottleworks]

Yea, I would suspect a shorted diode in the alternator. There are not any electronics in the trucks to pull an engine-off current draw.

 

[TommyG45]

It's dark enough, I am going to run outside and slap the "-" on, and check for lights.

Thanks for the suggestions.

TG

 

[doghead]

Put the top lever of the light switch, straight up to have all the lights off.

 

[FMJ]

If you have the digital light switch it will draw a bit of current when first connected, but should not be a constant draw.

 

[doghead]

The heater fan switch has power when the "ignition" switch is on also(as well as the horn)

 

[TommyG45]

Ok,

The dash lights being left on would have been way too easy right.....

The lights are off, no doubt, as a matter of fact, I didn't see any of the dash lights come on when I was playing with the switch, unless they are so dim, even in low light conditions you can't see them. (totally dark required?)

It's the manual switch, non newer model. I didn't see the dash lights come on even when set to bright setting, unless there was something else I was missing. Master switch was off.

Are the diodes replaceable in the field, like, literally in my field lol, or do I need to send it off somewhere and have it gone through.

I assume the diodes form a bridge to clip the negative edges of the sinusoidal waveform. I just got the deuce, so I am not that familiar enough with the mechanics or the electrical components. I have some knowledge of electronics.

Horn solenoid next, also I will pull the wires on the alt, and see if I get the spark. It's not a big spark, but enough to know it's pulling current.

Reverse bias mode as you mentioned could probably be measured in milliamps... A short make sense though.

I will keep checking and pinpointing, start with the simple stuff. If I pull the connections on the alt, and the spark goes away, can these things be rebuild by any Joe with a schematic and a soldering iron?

 

[FSBruva]

Also check out the -34 deuce manual - it covers almost EVERY electrical problem with a really easy to follow flow chart, with "Set multimeter for measuring resistance. Place positive lead here, and negative lead here. Is value less than ###?" type stuff. Very helpful. There also is the alternator manual, TM 9-2920-225-34 that covers the complete tear-down and rebuild of the alternator.

You should get something like 100K ohms going one way on the alternator, and ~ 80 going the other way. One thing that got me is the little flat bar that secures the two wires to the housing of the alternator wore through the insulation of the positive lead. Fun times. I found a local shop to replace my diode plates for $100, took them 2 days.

Matt