Hi,

I am fixing up and driving my truck that hasn't been used much lately and running into a problem - it is an intermittent electrical isssue that doesn't come around often, but can lead to me stranded...

It can drain my battery overnight to the point that the truck won't start. It seems to come and go without any rhyme or reason. When I am in the truck, I can recognize the problem because the radio won't turn on at all and there is electric static on the speakers (the speakers do some crackling). The radio fuse is fine.

The problem is I can turn off the truck and everything seems fine and go back in the morning and hear the speakers cracking once I turn the key and the batteries can be too low to start the truck - leaving me stranded.

I am hoping the clues might be enough for someone to have an idea of where the issue is??

Thanks for reading!

 

You'll need an ammeter, one with fairly high current capacity. You disconnect BOTH battery negatives, then connect the ammeter in _series_ between one of the battery negative posts and the terminal. You'll probably see a fairly high current flow. Then you have to start pulling fuses out, one by one, until you see the current draw drop. Whatever fuse you find causes the current draw to drop when you pull it, something energized by that fuse is still drawing down the batteries.

 

These trucks are old enough that some of the ground points are not as good, or perhaps are not working at all anymore. The radio acting like that is an indicator. Loosing power to the computer is another. One time, a friend of mine was experiencing problems with a 97 he was working on, and by fixing the brake light on top of the cab fixed the problem! What that told him was that somehow the ground was coming through that light. So any time on OBS truck comes in his shop with electrical issues, ground wires are cleaned or replaced before anything else is done. I ran new ground wires from both batteries on my 97, as well as cleaned up the old ones and put dielectric grease on the connections. My radio was doing the same thing as yours is now. Hasn't done it since I fixed the grounds.

 

Madpogue - I have a fluke multimeter and I think that measure up to 10 Amps - will that be good enough? I was measuring a different way - putting the multimeter in between the + terminal and the + wire. I will try your way, but a big problem is that when the radio and speakers are working normal, there doesn't appear to be any drain on the batteries - this makes it hard to troubleshoot because it is not a regular event...

Camp Springs - is there a diagram or list of the major ground point in our trucks? Or do I just follow the negative battery terminals and look for screws into the frame?

Thanks for help!

 

Both batteries ground to the engine, and they also ground to the fenders if I remember correctly. I cleaned up the connections from the batteries to the fenders, ran new ones off both batteries to the fenders as well, and to the firewall, and I put new ones from the frame to the body and the frame to the cab. There is also one or two from the back of the motor to the firewall that I cleaned. Also, check your battery terminals. I know that sounds silly, but I have found loose connections so many times after checking a bunch of other possibilities because I "knew" the battery connections were all good.

 

Depends on the load; there's a chance that it exceeds 10 amperes. I'm guessing since it's a Fluke, your meter has some protection against excessive current flow in ammeter mode. Positive terminal/post works; it's just safer to use the negative because it's safer to disconnect. In either case, you have to disconnect the other battery, since the two are connected in parallel.
Intermittents are always the fun ones to troubleshoot.... It's sounding like something is actually happening when the truck is unattended. Wouldn't it be cool to have a meter you could set up in ammeter mode, and it would alert you when the current goes above a selected threshold. Yeah, there's probably "an app for that" somewhere....

 

I did the meter test while pulling fuses and I think I found the culprit. Fuse #1 in the engine compartment. The manual says that it is "audio power". It was drawing about 240milliamps (I think that is how I say it, it was .24 on the fluke meter).

There is a CD changer hooked up to the truck (was here when I bought it). It has never worked right. I imagine the first step is trying to disconnect that and see what happens then. Any other ideas? Good news is that I think if I am happy without a radio, I don't have to worry about the drain as long as the fuse is out...

If anyone has any other ideas - please let me know. And thanks again!

 

Ah, another cardinal rule, forgot to mention. With electrical gremlins, if there are any aftermarket components, esp. installed by a prior owner, first thing to do is decommission them and see what happens from there. Your radio itself might be fine, once you take the CD changer out of the mix.

 

How old are the batteries? Are they matched? (same age, same brand and amps). Sometimes as the batteries age the will do funny things. I had one that would go dead with just the int lights on for a little while, but it would still test good.