DT466e No crank scenario, ground problem

Hello all,

Looking for a little help on a no crank (and therefore no start) DT466e.

Truck was cranking and suddenly stopped. Lost dash lights, brake booster (it's hydraulic). I figured batteries let go, took them out and set them to charge. Tried them after a while, same outcome. Tried a different set (tested them off the truck as well), same outcome. Could not get the starter to turn over even when jumping it directly by jumping the solenoid. Figured bad starter. Swap a new starter in, no go. Same result. Ugh.

Watched a few videos on similar situations, read around the forums a bit, decided to try swapping out the solenoids under the fresh air intake (responsible for sending voltage to ECM), nothing. Same outcome.

Started checking grounds and wires for chaffing, shorts, etc. Couldn't find anything but I did notice the grounds on the starter have voltage (like 6.0V). Exciter cable on the alternator also has low voltage, as does the frame and dash. Pulled the exciter wire off, pulled alternator power cable. At that point all the disconnected grounds were ok so I plugged everything back in to the starter. Tried to crank with alternator off, nothing. Put the alternator wires back on, same outcome (positive voltage where it should be grounded).

What is going on with this thing? Is the alternator somehow back feeding current to what should be grounded? Appreciate any advice / ideas. Thanks!

A.

 

OK thanks, will look into that. I think I get what you are saying. Will try that in the morning. All day today and no cigar, super frustrating. Ugh

A.