About Van Expertise Chevy 1008 pickup. Top to bottom. Suspension, drivetrain, ELECTRICAL.
They`ll take a beating.
Experience I take care of several of these beasts used for extremely severe service, off road, ditch jumping, rock hopping, buffalo chasing work horses.
Expert: Van Date: 12/21/2006 Subject: charging system
Question I recently purchased a 1985 Chevrolet 1-ton ambulance. The truck is running great. It has a 6.2 liter diesel engine with 24 volt starting system. I put two brand new batteries in it when I bought the truck and after driving it, the front battery (the 12 volt one) keeps going dead. I read some of the posts on here and have checked the light bulbs on the dummy lights and they are fine. But when the vehicle is running neither one of the lights are on. Most of the posts I've read on here talk about the alternators being one on the driver side and one on the passenger side, however, both of my alternators are on the passenger side. Both alternators have regulators on them that say 28 volt. When I put a meter on the second battery (24 volt) it will check 3 or 4 volts higher so it is charging fine. I have no idea what to do, hoping you can help. Thanks!
Answer That truck has a very intricate, and expensive charging system.
In addition to the built in regulators, there is another regulator, and an isolator on the left fender under the hood.
I would check the front battery with a volt meter, both before starting the truck, and after, to see if it seems to be charging. Lets assume it is.
So what is killing it?,,, Almost every single thing in the truck is 12Volt, and operated by that front battery.
The starter is the only thing that needs the second battery.
The truck, and the ambulance body both have a bunch of relays for different things. If a relay stays energized, it will drain that battery.
One relay in particular, is in the dash, and controlled by one of those rocker switches near the ash tray.
That switch is marked GPFU, I believe. That is a gas particulate filter unit. Even if the unit isn't working, if that switch stays on, the relay will be energized, and kill the battery.
Another relay is the blackout lights, controlled by a toggle switch under the headlight switch.
I would get in the truck with the ignition off, and flip those switches, and listen real close to see if you can hear a click under the dash.
Then keep the switches all turned off.
Back in the bed compartment. On the drivers side, under the lower bench there are a bunch of relays, for lights mostly. Make sure all are off.
