Ford 3930 Electrical Help

[aa799]

Hello,
Long time stalker, first time poster. Hope someone can help me track down my 2 electrical issues. I have a 97 Ford 3930 that I picked up about 4 months ago.

First, When the tractor is running, My fuel gauge works and my temperature gauge does not work when the lights off. Then when I turn the lights on the temperature gauge works and fuel gauge does not. ("works" = looks like its reading correctly)

Second, My front lights just stopped working. Here's what I have checked with a voltage detector.
- No voltage at the light
- No voltage at the fuse panel. Doesn't look like any fuses are blown.
- Voltage at the rocker switch from the hot wire, but th voltage detector doesn't light up when I bridge the connection.

I haven't got my hands on a wring diagram, but correct me if I'm wrong. Battery to rocker switch to fuse to light? At least that what it looks like when I tested out the rear lights.


Any ideas?
Thanks in advance

Ted

 

[3930dave]

Somebody may have been playing with the original wiring, as a few things don't make sense.

1) Normal factory wiring would have routed power to the Fuse first, then Switches/Loads - you can start fires getting creative with that practice.

2) Describe your voltage tester (make/model ideally); it sounds like it may be a non-contact type ?

For first-pass testing, I prefer just a basic 12v (many are rated for 24v too) test light - ground clip and screwdriver handled probe.

3) I'd want to start with verifying power at the Fuse panel, not much will happen w/o that. Check the wiring on the back of the panel if you can - a TBN'er with a decade newer 'bota had some rotted wiring on their fuse panel recently.

Mine's about 5 years older than yours, and I don't have a wiring diagram for it, else I'd share. You'll need your years' diagram to verify what the factory wiring originally was, and to verify switch function.

Rgds, D.

 

[aa799]

1. That's what I would have thought, but the lights are on a two way rocker switch. So From the battery to the switch, then to two different fuses (rear lights, front lights) then to lights.

2. The voltage detector that I'm using is a normal ground clip/screwdriver lighted handle probe (6v - 24v).

3. When the rocker switch is positioned on for the rear lights, there is power at the fuse box for that fuse. When the rocker switch is positioned on for the front lights, there is no power at the front light fuse. Now that I think about it, you're probably right about something is wrong with the wire from the switch to the fuse.

Do to the little ones, I have a 1-2 hour window around midnight to do my barn work. i'll see if I can access the back of the fuse box hopefully tonight if not tomorrow night.

Thanks.

Any Ideas about the fuel and temp gauges?

 

[3930dave]

You should buy a lottery ticket Ted. Found this, just now:

http://www.tractorbynet.com/forums/owning-operating/257034-ford-newholland-3930-wiring.html

Somebody shows up for only 1 post, and uses that single visit to share critical documentation !

They sound like somebody I like to buy a beverage for :drink: !

Obviously I can't promise yours will be exactly as shown there, but it may be pretty be close. Let us know.

I'd take a shotgun test approach first, if you haven't already...... Check all fuses for +12, on both sides of the fuse. Pay particular attention to the fuse off the Accessory (ACC) position on the Ignition switch, in the diagram it is on the bottom of the block.

Next, make sure that the ACC line connects properly from it's fuse to both the Temp and Fuel gauge. Then check that you have good ground wiring on both gauges.

What I'd expect, and can be seen on the linked diagram, is the light switch (wrt. the gauges) should only be feeding power to the instrument panel bulbs. Trace that power line for the bulbs, and see if it goes anywhere it shouldn't. The light switch feeds 2 fuses, one goes to a headlight. Only one headlight is shown - don't know if the other is implied, or on another page.

If you have power coming in to the Light switch, but not out, with this schematic you can test jumper that line to see if you get your headlight back.

Without somebody modifying the wiring, or taking things apart and hooking them back up wrong, what you describe doesn't make sense.

(I believe you , that was just me over-stating the obvious ).

Rgds, D.

 

[aa799]

Great find. My goggling isn't what it use to be. Didn't get a chance to take a look this weekend. Hopefully the stars will align and i'll have an update this week.

Thanks again for all the direction.

-Ted

 

[3930dave]

You're welcome Ted, anytime.

Just paying back the universe for all the help that I've received on here. :thumbsup:

Rgds, D.

 

[aa799]

2 months later I finally got back to the tractor. What a busy cold winter.

Dave,
Went through all the fuses and they looked good. Took off the Guage Cluster and found the both problems. There was a short in lead wire from the switch to the fuse panel. That fixed the head lights. The back of the Cluster was pretty weathered, So after cleaning it up, it fixed the fuel and temp gauges.

Thanks again for all your help.

 

[3930dave]

That's great news Ted !

Thanks (and you're welcome, anytime) for posting.... always good to see a successful repair happen !

You've added to my project list though .... from your description I'll be taking my instr. panel off soonish....

Of the 2, my Temp gauge has worked fine, but since getting my 3930, the fuel gauge always bounced up and down. On a tractor, I consider the Temp one to be the most critical, so I put off digging into this figuring it was a sender problem. Still could be that on mine, but it's a quick low cost check to look over the instrument panel connections.... on my To Do list now....

We're gettting more daylight now, but I'm sure you're glad to get your headlights back too..... Bonus marks for not being an expensive fix :thumbsup:

Rgds, D.