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So I picked up my neighbors 99 powerstroke XLT 4X4 for a decent price. It has had a recent history of charging problems. So far he added two alternators, new batteries, and a trip to the local Ford dealer. Things seemed to work for a while, till I picked up the truck. Seems like the problems returned with a vengeance driving it in cold weather. When I start the truck up it won't charge at idle when cold... this can go on for several minutes, so I've ruled out the glow plug delay. Once the motor build some heat (above 160) and I start running the engine above 1500 or 1800 RPM I can see the voltage rise from 12.1 to 14.3 and it'll stay there for the duration, till I turn the truck off and it'll do it again, however, it'll pick up voltage right away when I rev it a little. I did all the testing and it seems to fail at I 904. I only have .017 volts at the connector at the alternator. I've read that others have had this problem and have repaired it by cleaning the connector plug where the lg/rd connects to the harness. Anyone know where to find this connector? I've done a quick look through and cant see it, the previous owner put an Air Raid filter on it, and it's covering up a lot of space to poke around. My other thought is to run a new LG/RD wire from the alternator plug to the cluster...ugh Thanks in advance for any help. And yes, this truck has inspired me to get a premium AAA membership,and a premium member upgrade
Judging by your comments, you do not have dual alternators. The wire you are looking for is the LG/RD one. Here are the connector locations. You can trace the wire from either one.
Having said that, if the alternator is charging for awhile then quits, it may be the onboard rectifier or voltage regulator that is pooping out. Get a quality alternator like one from National Quickstart. They also do an external rectifier to take the load off the one in the alternator. These rectifiers commonly fail due to heat.
I do not know where this connector is. But this does ring the sound of a loose connection due to thermal expansion. This connection could be external and accessible, or internal in a device and needs replacing.
The alternator grounds through the alternator body, through the bracket to the block and finally to the batteries via ground cables.
Each of these points of contact need good continuity. I use a large flat file on alternator and bracket and clean block and ground cables with wire brush.
Some people have run a cable from battery ground to alternator hold down bolt.
The alternator grounds through the alternator body, through the bracket to the block and finally to the batteries via ground cables.
Each of these points of contact need good continuity. I use a large flat file on alternator and bracket and clean block and ground cables with wire brush.
Some people have run a cable from battery ground to alternator hold down bolt.
+1 on this. I forgot that grounding can be an issue on these trucks. I have gone nuts with the grounding cables on my truck and added individual HD cables for the alternator, transmission, cab, transfer case and a few other things I can't remember right now.
Thanks guys, my truck has a 130 amp alternator, doesn't have the external rectifier, nor the connector shown on noob's pics. Seems like once things heat up the issue goes away, but I do mean heat, not like garage warm but operating temp. hot. I swapped a known good alternator with the same results. Thought while I was at it I'd pick up a new three wire connector as a cheap (maybe there's a a bad connection) what if fix, yeah, no, not cheap $45 for the plug . I'm gonna try the secondary grounding idea, seems like a sound idea. Kind of dreading climbing all over that engine compartment to trace that wire, but if the ground doesn't work, I'll be diving in. Also was gonna get a new motorcraft positive battery cable, but they seem to have disappeared from the market. In any event too much snow here to worry about this .. time to destroy some powder up on the hill
doesn't have the external rectifier, nor the connector shown on noob's pics. Seems like once things heat up the issue goes away, but I do mean heat, not like garage warm but operating temp. hot.
The connector and external rectifier are aftermarket items from National Quikstart. A stock charging system will not have them.
The problem going away when the engine is hot is the opposite of my experience. My charging problems came when the alternator got hot and the diode(s) in the onboard rectifier failed.
. I'm gonna try the secondary grounding idea, seems like a sound idea. Kind of dreading climbing all over that engine compartment to trace that wire, but if the ground doesn't work, I'll be diving in. Also was gonna get a new motorcraft positive battery cable, but they seem to have disappeared from the market. In any event too much snow here to worry about this .. time to destroy some powder up on the hill 
