Ammeter Tic: PhilSine? Wesdog? mdill?

[Thomas DeBusk]

My '83 Wag Limited (WL) has an ammeter tic. Under certain conditions it will tic hard and quickly to the right. Usually it's with the lights on and my trailer connected.

This is a vehicle where the interior lights don't work and the cigarette lighter only works when it's hooked up backwards. Oh, I regularly blow the fuse that powers the dashboard lights when my trailer is hooked up, too.

And, no, it's not for lack of trying to fix it. I've been deep into the wiring under the dash and all through the tailgate.

[Bob Barry]

Put both leads to the ammeter on the same stud on the back of the gauge, and see if your odd problems go away. Of course, disconnect the battery first.

[ September 26, 2002, 09:29 AM: Message edited by: Bob Barry ]

[PhilSine]

After posting my knowledge of automotive electrical systems a few days ago I am convinced that getting rid of the ammeter and installing a volt meter is one necessary change to make and is now on my "To Do" list.

As for your problem.....

The hard tick to the right indicates a momentary increase in current. That increase is enough to draw more than 60 amps I'm betting and that exceeds what your wiring system can handle on a constant draw. A momentary draw is much less harmful but still not normal and not good. The massive current flow is most likely caused by an intermittent ground somewhere on the vehicle.

Either your trailer has a short or your lighting system has one. I'd start at the trailer as the problem seems to exist when that's hooked up. If you can't find a fault on the trailer my advice is to re-wire the head light and tail light circuts from the dash all the way to the lights. They probably need it anyways.

Good Luck.

[mdill]

Itermitants are the worst things to find. How hard is the tic to the right ?,
Mine ticks around some just running the turn signals.
The only real advice is to see if you can duplicate the problem, have a buddy
watch the meter and start crawing around wiggleing the wires as you go.
Replacing the harness as Phil suggests is tempting at times but with new ones
none existant, and used ones you are likely to just get some elses problem,
search wiggle, remove fuses untill you are able to isolate the circuit. Fixing it
is then the easy part. (Tail gate feed though is a likey place, anywhere wires
go though a body panel is suspect, very rarely will a short be internal to a
harness but it could happen.)

Mike D.

[mdill]

Thinking about it some more, there is the possabily that rather than
a intermitant short, an intermitant open describes what you maybe
seeing, alternators can not turn on and off real quickly, the feld winding
is a coil (inductor) and the regulator can not shut it down on a moments
notice.

Do your headlights flicker at times ?

If your head light switch was bad or the wiring to it had a bad connection
this could cause the load on the system drop for a fraction of a second,
not long in our terms but for a short enough time for the alternator to keep
charging at the same rate it was before the open occured since the current
does not have a path to the headlamps it would be dumped though the
ampmeter into the battery. If this is the case most likely not a fatal problem
that will cause a melt down. (A bad headligh fillament might also do the same thing
like a burned out light bulb that you can get working again for a short while by shaking it)

Mike D.

[Thomas DeBusk]

Never noticed a headlight flicker.

The tic is very hard and very quick.

I've already replaced the headlight switch. Did that because the parking lights were staying on after the headlights were turned off. That was because a relay in the black box that's part of the factory trailer wiring harness would stay closed. Mechanic "cured" that by bypassing the relay. Lost my interior lights at the same time. I know that didn't cure the problem—only masked it—but at least my parking lights aren't staying on any more.

"an intermittent ground somewhere on the vehicle" I like that. I don't mean to bite the hand that's feeding me, but I had to chuckle when I read that. Could you narrow that down a bit more? I haven't quite torn out every wire to check it, but I'm well on my way, and still no luck.

I suspected the tailgate feed, too, but I tore the rear all apart and I still couldn't find my other problem.

I also took all the lights apart and couldn't find a problem in the sockets.

Thomas

[mdill]

Good luck with her,
It is hard enough to find these in person but by remote control, it is at best just a guess.
I would first look at the work the "mechanic" did, I am personally not familiar with
the factory trailer wiring, so can offer no help off hand.

Mike D.

[mdill]

OK more thinkin,

Do you ever see the amp tick to the left ? (All the accessory loads are to the left)
If it only ticks to the right that would leave only the yellow battery charge wire
and/or the battery itself as the problem areas.
Check the yellow feed though the dash connector then though the engine
harness, that goes along the right (passenger side) valve cover (V8 I dont
have a I6 to referance) the harness is still nicely tucked up in the plastic
conduit I hope, other wise it could fall on the exaust manifold and short.
The infamous factory duct tape protected splice from H*LL is in tact ?

I have had a battery get an intermitant internal short, that caused a
a problem on my 72 Suburban once, took out its fusable link.
How old is the battey ?

Mike D.

[PhilSine]

mdill's right on the availability of wiring harness' for any part or our FSJ's. If it were me & I decided to re-wire I'd look in my manual at the electrical schematic and purchase a few rolls of the color and size wire they used and replace it on wire at a time using the old stuff as a guide for the new stuff. This applies for the head and tail light wiring portions only as they are independent of the engine/dash wiring harness bundles.

Also, like mdill said, the point where the wires go into the light assemblies, the tailgate, or at the trailor connector are good places to start.

[Thomas DeBusk]

Always and only tics to the right. These are great suggestions and I will check them out. I have had a short to the passenger's manifold that burned a wire, but it has been repaired. That was a red wire that ran to the starter relay on the fender. The factory duct-taped wire in that area is intact. Very impressive.

This Wag is V8.

Last fall I had an underdash smoke episode. Another mechanic repaired that. But he didn't get it all fixed. I later discovered a blue wire on the ignition circuit that had been turned extra crispy. I took it apart from the harness and traced it all the way to the firewall. Then I took all the insulation off, cleaned up the ends, and re-wrapped it securely. But my ammeter tic was in place before all that. As was the parking light problem.

Oh, I didn't mention my radio goes south in rainy weather, did I? Comes back when things dry out. Why do I love this vehicle so much?

Thomas

[mdill]

If it only ticks to the right, then it should be pretty easy, the only wires to the
right (charge side ) is the Yellow wire from the amp meter -> splice from H#LL
where it connects to the regulator sence wire then on to the solenoid batt lug.
Put a volt meter on the yellow side of the amp meter, does the voltage
drop or rise during a tick ? If it rises the voltage regulator maybe be going
and sticking on alittle to long, if the voltage drops it has to be an intermitant shrot in the
amp-> batt/sence wire or batt itself (Thats all that should be there)
This only applies to the stock way you jeep came from the factory, I have no
guess as to how things maybe hooked in your rig after the number of fixes that have
been done.

Mike D.

[krob725]

Originally posted by mdill:
have a buddy watch the meter and start crawing around wiggleing the wires as you go.
Mike D.also look for places where this harness is touching the body or frame. could have a bare spot somewhere that touches when you hit a bump or go around a corner. as far as the radio goes, i'd check the antenna mount. it might not be getting enough ground on the fender or might be a little loose.
krob725