hi guys

been having some electrical gremlins playing in the charging system on my work truck (93 W250).
last week i had to get pushed off the freeway (after blocking downtown san francisco traffic for half an hour) by the highway patrol when the truck completely died and had not even enough juice to run the hazard lights... anyway i bought a new battery to get home. after that i was putting the battery on charge overnight and running off of that until i had the time to look into what was going on with (what i thought was) the alternator.
i spnt a bunch of time in the archives but i couldn't seem to find what i was looking for.
in any case, since then the voltage gauge shows the alternator working intermittantly, sometimes charging, sometimes not.
any clues as to where to start looking?
and, thanks!
jeff

 

Check the crank sensor and the wiring to it. Sensor gap should be 0.050 (checked with a non-magnetic feeler, a folded over matchbook cover works OK in a pinch). The wires often get chafed where they run around the front left corner of the head, and also down low where they run through a harness hold-down. Also a shredding fan belt can take them out.