View Full Version : Intermittent Charging problem

04-06-2009, 09:58 AM
just in the last week or so I've seemed to (re)find a charging system problem on my '91 truck.

I'm getting the diode failure (charge system failure) warning light (handbrake exclamation plus battery) sometimes while driving.

I usually see it at least once while driving here and there. When it's on, it's only on when I'm under a certain rpm. If I break the threshold (55mph in 4th gear, 65 mph in 5th gear, etc.) then it goes off.

But then later on in the drive I'll drop it down to idle or just a lower rpm and it doesn't go on. But like I said, it's intermittent, so sometimes it will.

The battery is only a year or two old, the alternator is less than a year old (I'm guessing 9 months or so), the alt. belt should be tight since I checked it a couple weeks ago, but I can check it again; any other ideas?

The only thing I can think to check is that maybe I'm missing some teeth on the belt or that it's not tight enough.

04-06-2009, 10:03 AM
Besides checking the belt tightness, I would check and clean all the wire connections. Sounds suspiciously like a loose ground or connection some place.