Help Diagnosing Electrical Problem

[madams557]

Okay, I went out this evening to move the 1978 FJ45 in off the street because the city is resurfacing it tomorrow. Anyway, I get it to start it. It turns over and chugs a little, then stalls. Go to start it again, and nothing happens. No click click, no lights, no electricity at all. Think maybe the battery died, but to die completely like that seemed strange.

So of course panic sets in because the city threatened towing anything left on the street starting in the morning.

I bring the FZJ80 around and hooked up jumpers. NOTHING!!!

Fumbled with the jumpers a bit, turn the key and get a little bit of action. Then NOTHING!! Not even headlights. Not even dull headlights.

Luckily, I had a brand new Sears Diehard battery that I picked up a few months ago under warranty for a CJ7 that I no longer have. Put it in the truck and everything is fine.

Here is my questions. Why didn't the FZJ80 w/jumpers get it going? I just recently completed my powersteering conversion and had to move the alternator over to the passenger side of the block which required adding some wire. Have I created myself a short somewhere? Is there a short somewhere that I haven't created by moving the alternator?

OR was the battery just dead? Pretty freak'n scary. To think that I could be out somewhere and have the battery die, and not be able to jump it with another truck.

By the way. I happen to find a fuse blown. While dorking around with the fuses while the truck was running, I attempted to move the lower fuse and the truck would die. Any connection or common.

With the brand new battery in there, where should the amp meter be at?

Any suggestions appreciated.

 

[Bodean]

My 78 FJ40 amp meter runs a little above half way at start-up. Once warmed up the amp meter runs about in the middle. I don't know if it's right but I don't have any starting problems. Trace the wires and make sure all of the connections are good. I assume you just lengthened the wires. Just my .02

Later!

 

[rgentry]

If the old battery shorted out, that is died by an internal
grounding of posiitive to negative, you would get exactly
the behavior you described. I had a battery that was
intermittently shorting out. Difficult to troubleshoot and
hell on the charging system. If you remove the positive
lead from the battery being jumped and the system jumps
OK, then something is bad wrong with that battery. I've
only seen this once so I guess it's pretty rare.

 

[zetasig]

Ill throw in 2 cents. I would say if the Old battery was working fine until you tried it last night, It didnt run down all the way to where the lights would not even come on. (how long did the truck sit since the last time you drove it?) I would say it was a bad ground, or corroded connection. By putting the new battery in you moved or broke up the corrosion and made a good circut again. try this. put the old battery back in and see if it works. or put the old battery in a different vehicle and test it. Or take the old battery to pep boys and have them test it. You need to rule out the battery before the vehicle.

The blown fuse throws me.

Is it possible the old battery was low on water?

Also what fuse was it. What does that fuse run? in the owners manual or FSM.

 

[madams557]

Bodean - yes, I did have to lengthen the wires.

Rgentry - I will attempt to test it tonight by removing the positive lead to the battery and trying to jump it.

Zetasig - the truck sat for about 6 - 7 months while I was doing the P.S. conversion, however I have driven it 3 - 4 times within the last few weeks without a problem.

Thank you gentlemen. I will run some different test tonight. The battery connections are pretty corroded, so I'll clean them up. Then put the old battery in my FZJ80 to see if it is the battery.

Maybe my jumpers are bad, they are about 12 years old???

Then I'll check the FSM for the fuses to see what is what. I don't have the cover so who knows.

Now, if I wanted to check the rest of the electrical system without the battery, especially to see if I have the alternator wired properly, I should be able to start the truck, disconnect the battery while it is running, and a properly connected alternator should create enough charge to continue running the truck and all the accessories - RIGHT??!?!

Michael

 

[Jukelemon]

Go test the battery at an autoparts store FIRST. That way you are not guessing.