Bouncing voltmeter... occurs when truck hits a bump.

[gmanpaint]

In the center of the firewall, to the right of the computer wire harness connection. There are 2 ground straps under the rig on both sides as well. These are connected to the body mounts in front center of rig.

 

[Blacksheep Josh]

Well I do know in my accident my front most body mount was damaged. Like right under the radiator area? I'll inspect those locations.

 

[gmanpaint]

Right under the windshield (under hood), to the left of the wiper motor

 

[92exp4x4]

Sounds like it was a bad accident, glad you are ok.

I would inspect all the wiring in the front of the truck. If it was damaged that much, i would have replaced the harness from a donor just to avoid electrical issues. Start the truck and pull on the harness and move stuff around. Try to recreate the problem. Ford's technical term for this is the Wiggle test.

There is no telling what wires may have been broke or damged as the body folded in ways not normal to its intended use! You definantly have a short somewhere. Look for burnt or melted wires or pinched/cut harness covers (that plasic tube stuff). The wires inside may be damaged.

By the way an alternator will typically put out about 13.5 to 14.5 volts at idle and stay there when RPMs increase.

Good luck, let us know what you find.

 

[gmanpaint]

Well I do know in my accident my front most body mount was damaged. Like right under the radiator area? I'll inspect those locations.

Sorry Josh, I didn't say that correctly. The 2 ground straps I am referring to are on the sides of the rig, under the door area. There are body mounts underneath, kinda like behind the front seats along the frame rail. I doubt these will make a difference for your problem though, I was just letting you know there were more ground straps besides what was on the firewall.

 

[Iceking007]

I have tryed to read through most of these but some of this info might be reapeated; I assume a fairly new thread is still requiring help.

1- with an accident like this it is mostlikely you have bad wirring as you bump the wires short out as previously mentioned turn elecs on and lights and do a shake test as mentioned jumping on the bumber may work also.

2- if you have results in above you can also try disc all fuses that aren't needed for the lights as that is the apparently connected problem and see if it rrepeats... also try minimum system running fuses in a parking lot just to run not signal lights ect and see if it happens over a bump.

3- battery getting voltage or not accepting charge ect any related problem would not be problem matic only over a bump... it either works or it doesn't... this problem does not sound like a bad battery to me.... possably a bad alt if the windings inside are warring out could cause a problem over bumps; do you notice a problem with any other electrical problem or just the head lights and volt gauge? do your cluster lights dim at the same time or radio ect?

4- when the batter volt gauge goes down that means there is a heavy load through the electrical system eg a short... notice how when you put up your windows when they stop and you hold the switch your gauge drops

Hope this helps just a few things I could think of.... I'll try to keep an eye if you solve it!

 

[Blacksheep Josh]

So I decided to remove any and all wiring I've added over the last few days/years... I removed a total of 4 wires I believe... includes both wires from alternator B+ side adn alternator bracket, can't remember what I had teh other two connected to. I think it was a mix of from battery to fusebox and an extra solenoid to fusebox wire...

I left the extra wire connected from body of Explorer to the negative side of the battery.

Working perfectly. Explain that.

The ONLY thing I added was water to the battery because it looked low... also took the battery COMPLETELY out and piggy backed it onto my boys Jeep for about 20 minutes, then took it and had it tested. After that is when I removed the wiring. Now I'm moving onto getting a sealed dry cell battery to install into the hatch area for my sub system.

 

[Drednaut]

I have added a 4 gauge wire from B+ side of Alternator to + post of battery.
I have added a 4 gauge wire from Alternator bracket to - post of battery.

Only difference is now the voltmeter stays consistently in the low end of things. It won't come up to where it used to sit when it was normal. After work tonight, I'm going to go by Wal-Mart and buy a tester and see where the volts are sitting at different points. I have one at home but I forgot to bring it with me to college. I think I'm just going to have to test everything and see where the problem is.

I did have another idea though, if the headlights dim when the voltmeter dims, that would mean that "failure" of volts is happening along a power wire they both see. Where would that be?

Oh, and the headlight switch was replaced over the Summer, I double checked it a few weeks ago when I was installing a switch for something and it looked fine (it was doing this back then as well)

Also, where is the ground for the dash electronics?? There's got to be one up underneath there somewhere.

For a while i had the same problem on my explorer it was intemintant and i never found the source of the problem but i would check the connections to the alt.

 

[Blacksheep Josh]

I cleaned the plugs that went into the alternator. Up until a year ago it was the stock alternator that was in there, it had some grease looking stuff, probably old dialectric grease or whatever it's called. But I cleaned it all out, replaced it with new grease, for 24 hours now it hasn't dimmed at all under normal conditions.

Only time it dips now is when I click my subs on, or turn the heater from off to high in a split second. Same thing when I put my windows up and it dips a bit. So far so good though. I'll be adding another battery I think within a month or so for the sub system, until then I'm running them on super low volumes.

Thanks for all the input though guys, I appreciate it.