Help: Electrical PROBLEM

[retcap201]

2004 LB7 100,750 miles

1. parked truck overnight. both batteries dead.
2. replaced both batteries, started right up, alt guage showing about 12 volts. parked for about 3 hours, both batteries dead.......
3. recharged batteries and with cables hooked up, and truck not running, dropping voltage about 1 volt per second....alt hot to touch
4. replaced alt and started again, still only showing 12.5 to 13 volts....
5. disconnected postive battery cables....alt showed 13 to 14 volts
6. reconnected batteries and turned off truck, waited about 10 min. batteries dead
7. Cannot find a short that would cause batteries to drain so fast....

Help.......

 

[Chevy1925]

its gotta be a big wire to be pulling that many amps. check the starter wires, relays, and anywhere those big positive wires run (including the one off the alternator and so on). you got one pinched somewhere big time shorting to ground. ill bet those batteries arch pretty bad when you charge them and hook them back up too

 

[retcap201]

Yep. Going to look at starter this afternoon.

 

[Sledhead]

Glow plug circuit commanded/stuck on? The solenoid may be welded closed?

BEWARE of EXPLODING BATTERIES! Wear a face shield and eye protection!

 

[Mike L.]

Check battery cable at starter for touching frame. I have seen it happen at my shop.

 

[retcap201]

Found it......
It was the glow plug, heater controller relay.
It was fried. Replaced it last night, truck runing great.

Thanks for all of the help.:thumb: