I have a 93 W250 with a cummins & manual trans & the air "toaster" preheater
I am having a problem with charging system not activating. As best I can tell, it is caused by an intermittent failure with the the wait to start sequence not starting or completing.
When everything works fine: tun on the ignition, the wait to start light will come on, followed by the water in fuel light, fender relay activates (click), then they all go out. Start the truck and the voltage indicator jumps up to about 13 volts.
The problem is I usually only go about 10 miles per trip. When I turn on the ignition either the Wait to start light does not come on at all or it comes on for awhile and then nothing happens. The charging system does not come on so the voltage reads about 9 volts then progressively drops to 8 and below with each successive trip and then I have to recharge the battery.
The thing is the truck starts fine (as long as I recharge the battery), so i have given up waiting for the wait to start sequence.
The best way I can describe it is that everting is happening in slow motion.
Usually after I drive around for a couple of hours
everything works fine: the wait to start light will come on, followed then the water in fuel light, fender relay activates (click), then all go out and the voltage indicator jumps up to about 13 volts.
If I try to start it a within about minute after everything is running OK, the whole system works fine. But if I wait much longer than that, the problem starts all over again.
I am confused about where to start troubleshooting because it works sometimes. I have tried:
The shop just replaced the alternator so I think that is OK
I replaced to the two fender mounted solenoids so I think those are OK.
Thinking that running the engine longer made it work because everything was warm, I have tried to fool the temperature sensor by heating up the air heater area with hot air gun while the ignition was on- a couple of times that could get the sequence going but it did not work reliably.
Since the engine truck starts fine, I would actually be happy if there were a way to bypass the preheater system if i could figure out how to activate the charging
Any suggestions would be greatly appreciated.
The shop guy suggested that it was a grounding problem and that I should trace all the ground wires. Does anyone know where I can get a wiring diagram of the system?
Linear Mode
