midland

98, automatic, 2500, 2wd, all stock

Yesterday I was driving home from a Christmas trip when the problems began. My check gauges idiot light came on, and I noticed the voltage gauge had dropped below 10 volts however the truck was running fine. I was around 40 miles from my final destination so I kept going as it was 16 degrees out and didn't want to stop in the middle of nowhere. I turned off the radio and heater blower to conserve power as I feared I may be running on just the batteries. By the time I reached the edge of town my voltage gauge was reading just above 8 volts. When I came to my first stop light I stepped on the breaks and all the lights on dash as well as the gauges went dead (I assumed the batteries were completely flat), however, the truck was still running. Approximately 1 more mile down the road the engine started making a louder noise than usual then all of a sudden every thing went back to normal. My headlights were no longer dim, all the gauges were working properly, the check gauges light went away and ultimately the voltage gauge was reading the norm just above the 14 volts mark. I drove the rest of the way home fine as well as drove the truck to work this morning with no problems.

Has anyone ever had this problem.

My next steps are to take the truck to a mechanic and have them do a diagnostic on the computer.

BigIron70

I would first check all connections on batteries, clean and tighten them all. Check charge wire from alt to battery make sure it is tight. Check the grid heater wiring, make sure those wires are not damaged or burnt. Just in case the grid heaters came on and remained on until fusible link wire burnt out. The wires come off battery positive to heater relay on fender.

torquefan

The alternators on these trucks are very problem free, but when they do wear out, the first components that fail are generally the brushes and slip rings. They wear until they are pitted and there isn't enough spring tension to hold the brushes firmly enough against the slip rings to make good contact. Anyway, I've seen a few cases where this started as an intermittent problem and resulted in permanent alternator failure as the wear continued. You got some very good advice above, but in addition, I would also suspect the alternator as a possible cause. Unfortunately, removing it and having it tested isn't guaranteed to prove anything if it isn't acting up at that moment. If you are familiar with these parts, you might want to pop the brushes out and have a peek.

shortkid

I had a very simular problem a couple months ago. I also could smell something hot, but couldn't find it until I opened the hood and touched the alternator. I took the alternator off and went to a rebuilder and found out the diodes shorted. This problem was off and on for about 6 months. Had it rebuilt cleaned all cables and changed 1 battery, works good now.