rmgill
Active member
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- Decatur, Ga
Hey guys, I'm helping a local PD out with their MRAP. Some dufuses tried to jump it off and now it's presenting a problem. The basic problem is this: While running (parked or driving) the dash indicator lights/gauges will power off as if a breaker was failing and then will reset.
The vehicle was apparently jump started or someone attempted to do so, unsuccessfully with civilian hardware and not via the slave cable and also apparently through the starter high-amperage connections. The problem appeared after that occurrence.
We tested a number of things and I found the following:
Batteries appear connected correctly.
The lower right battery (the one tapped for 12 volt) appears a touch lower in voltage than the other 3. 14.1 volts vs 14.5 volts for the others.
The problem presents MORE during running of the cab environmental (fan/heater/ac function) and the 12 volt gauge on the dash indicates a substantial draw down in voltage to 12 and 10 volts which are NOT shown on the battery on the 12 volt side. When this drawdown reaches 10 volts the power on the dash items goes out, there's a delay and then a breaker self resets somewhere and they come back.
The power loss is apparently traceable to the 12/24 volt load control module that is in the engine compartment proximate to the ‘firewall'. The cannon plug connections on it appear to be good and are not corroded. The load control module will indicate good green and 12 volts on the 12 volt output then will drop down and fail in output to 10 and it’s status indicator will go amber for a moment, then dark and then will go back to green after it resets. At the same time the voltage is falling and dropping out, the cab indicators will fail then return.
Notably, while the 12 volt system is dropping out, the 24 volt system stays on (24 volt lights, etc) unless they’re controlling 12 volt lights via relays in the panel that is on the co-driver’s area.
**
My ideas are that either the Battery Load control module is failing or it has a control system that controls it’s status that is failing due to a short of bad connection.
We did find a burnt connector in the back crew door area that has a possible low grade short between the 24 volt lead and what should be a connection to one of the lights for the back door light control switch. No idea if that’s a culprit but it’s an oddity.
Thoughts?
The vehicle was apparently jump started or someone attempted to do so, unsuccessfully with civilian hardware and not via the slave cable and also apparently through the starter high-amperage connections. The problem appeared after that occurrence.
We tested a number of things and I found the following:
Batteries appear connected correctly.
The lower right battery (the one tapped for 12 volt) appears a touch lower in voltage than the other 3. 14.1 volts vs 14.5 volts for the others.
The problem presents MORE during running of the cab environmental (fan/heater/ac function) and the 12 volt gauge on the dash indicates a substantial draw down in voltage to 12 and 10 volts which are NOT shown on the battery on the 12 volt side. When this drawdown reaches 10 volts the power on the dash items goes out, there's a delay and then a breaker self resets somewhere and they come back.
The power loss is apparently traceable to the 12/24 volt load control module that is in the engine compartment proximate to the ‘firewall'. The cannon plug connections on it appear to be good and are not corroded. The load control module will indicate good green and 12 volts on the 12 volt output then will drop down and fail in output to 10 and it’s status indicator will go amber for a moment, then dark and then will go back to green after it resets. At the same time the voltage is falling and dropping out, the cab indicators will fail then return.
Notably, while the 12 volt system is dropping out, the 24 volt system stays on (24 volt lights, etc) unless they’re controlling 12 volt lights via relays in the panel that is on the co-driver’s area.
**
My ideas are that either the Battery Load control module is failing or it has a control system that controls it’s status that is failing due to a short of bad connection.
We did find a burnt connector in the back crew door area that has a possible low grade short between the 24 volt lead and what should be a connection to one of the lights for the back door light control switch. No idea if that’s a culprit but it’s an oddity.
Thoughts?
