1989 Bronco - Need help tracking down a constant drain on my battery. I connected a test light between the positive battery terminal and the cable and it lit showing current was flowing with everything turned off. I pulled fuses until it went out with the #5 fuse which I show is for map lights, back-up lights and turn signals. With the fuse in everything works fine but something is still allowing current to flow in that circuit and I haven't been able to find the source yet.

Anyone have any or tips on finding the drain? Any help is much appreciated.

Thanks

 

did you check your alternator?i had the same problem as you are having and i took my truck to advanced auto to have the charging system checked for free.turned out i had a bad diode in my alternator so i bought a new alternator problem solved.....if theres an advanced auto near you have them test it its free.

 

If #5 fuse makes the testlight go out, then that circuit is the drain.

I would first double check what that fuse serves. I don't have a diagram of that year with me, but I am surprised the same fuse feeds the map lights and the turnsignal lights.

If it does feed the map lights, I am wondering if it also feeds some of the courtesy and underhood lighting, like the light in the glove box. You know, the one that is supposed to cut off when you shut the hood or close the lid.

Here's a diagram. It's not necessarily correct, but it shows #5 feeding the back-up lights and turn signals, but not the map lights?

http://www.autozone.com/images/cds/g...3d800a3a5c.gif

 

Thanks Franklin2, I was also surprised about the circuit incorporating the interior lights which I have checked and can't find any staying on. O also thought that since something was wrong in the circuit maybe the backups or turn signals wouldn't work right but they do. Am I looking for a bare section of wire somewhere that is shorting to ground or what else could be causing the drain through that circuit?

Thanks for the response.

 

The 89 Shop Manual say that fuse #5, 15 Amps Lt. Blue is protection for:
Turn Lamps; Backup Lamps, Rear Window Defrost; Overdrive Transmission.

 

You're right subford, I forgot about the last two. My particular truck doesn't have the rear window defrost and is a C6 not the overdrive tranny. I've got concentrate on the signal & backup lamps. The drain is there somewhere...

Thanks.

 

The 89 Shop Manual say that fuse #4, 15 Amps Lt. Blue is protection for:
Exterior Lamps; Instrument Illumination, Glove Box Lamp and Map Lamp

Image of the fuse Box.
http://i54.photobucket.com/albums/g9...nel/88Fuse.gif

 

I checked #4 and the Test Light didn't go out so it's not the source but I did check all the interior lights and didn't find anything staying on. The underhood light isn't working right now at all. One other weird thing that is happening is the blower fan will still run with the key off unless it's in the off position. I don't think this is normal as I believe if you shut the truck off with the fan on it should stop when the ignition is shut off. This is a separate issue from the #5 circuit but is something else zi've gotta track down. Any thoughts?

Thanks for any advice.

 

I would look at the Ignition switch (not the tumbler) and plug.
Fuse #9 should get power only in the run (maybe ACC) position.

 

I'll check that out. I have kinda been wondering about the switch itself as a possible source since my issues are with items that should only have switched power. The ignition switch itself is not really hard to turn but feels almost like it's full of peanut butter and is gummed up. Maybe some contacts are not making the best of connections in there. Maybe it needs to be taken out and examined/cleaned?

 

I do not think you can take it apart and get back together unless you are very, very good.
I would think maybe a new switch and plug pigtail is what you need.
You will just have to look at them to see if the power goes off and on and what shape they are in.
You do know that the switch is located down low on the column near the floorboard and can be adjusted on the column to make the new one work.

 

I guess I'm thinking of the switch on the column that you put the key into. I hadn't thought about the switch that you are referring to. I'll look it up in my shop manual so I know what I'm looking for and see what it says about testing it.

Thanks.

 

You put your key into the tumbler (Ignition Lock Cylinder) not the Ignition Switch (unless it is in the dash).
The tumbler will turn a cam (rack and pinion) moving an Actuator Rod that is hooked to the Ignition Switch.

 

Duh, I don't know why I didn't catch that in your first post. The #5 fuse is powered by the keyswitch hot wire. So no way could it cause a drain with the key off, unless of course there is something wrong with the keyswitch or something that is powering the circuit all the time.

I think you need to concentrate on the power thing, and that will fix it. The first thing I would do is make sure the blower is still messed up, and then get under the dash and pull the plug on the ignition switch(on top of the column). If when you pull the plug, the blower stops, then you know for sure you do have a problem with the ignition switch.

 

Sounds like a plan to me. At least I know where I should concentrate my efforts.

I really appreciate the help.