Smoked Ammeter

[FourDoorScore]

Hello group,

I recently upgraded my motor and drivetrain, but neglected to account for a larger output alternator on the big motor. so a few months later i noticed my ammeter was pegged even with the motor off. next drive to work, i just about burned off my thumb print pressing the ammeter's glass face to check for heat. this was followed by the red 10 gauge wire melting right at the firewall. So, I ran a new wire and i bypassed the (smoked, pegged, and corroded) ammeter.

Q: Since the ammeter also powered the buss bar, what is the best way to repower it?, and what is a suitable sized fuse to protect the circuit with?

also, assuming the buss bar itself is shorting to the dashboard panel, does anyone know of a workaround to power it and insulate it?

thanks for any info, its really appreciated.

[Sterno]

The Ammeter does not power the buss bar, this is a common misconception.

Power to the buss bar comes from the ignition switch via the brass strip that goes to the fuel gauge ,the red 14ga wire from Ign swithch hooks in to there. The buss bar is only riveted to the insulating washer on the back of the ammeter but not electrically connected to it..
I don't know why Ma Mopar did this but I suspect that some engineer "thought it was a good idea" at the time!

[FourDoorScore]

Hmmm, that explains a few things. In the schematics it appears connected. I'm still getting some continuity from the buss bar to the dashboard, so there is a short somewhere, but not necessarily there.

Thanks for the info. there is now less possibility that i will arc weld something in my dash.

I guess that 10guage red can be wired directly to the fusebox instead of routing up and into the dash cluster.

thanks again sterno

FDS

[elacruze]

Very common, here's the best solution I've seen, as well as lots of other great electrical bits in the website;
http://www.madelectrical.com/electrical ... uges.shtml

[wideblock]

sounds to me like your voltage regulator stuck. or the gauge was just finally bad. i have bypassed a lot of the factory amp meters by just connecting the wires together behind the dash and running an after market gauge. it doesnt have to run thru the gauge for the charging system to work.

[FourDoorScore]

I popped out the inst. cluster and wirenutted the the ends togater. next is to pin down why my gas guage thinks its eternally full, and the thermostat pins on the H. first i'll try the grounds, and then i'll make sure the rubber boots are connected well, and third i'll make sure they aren't getting too much voltage. I noticed there was an inline voltage reducer by the bussbar. i'll start there.

Hey again trey

thanks for the link

RW

[wideblock]

the fuel gauge did that to me once before. found there was a bare spot in the wire between the tank and the gauge, cant remember if i replaced the wire or just repaired it. might be a good place to start, a full gauge means its dead shorted somewhere. the other gauges being pegged out, i would be suspicious of the voltage reducer as well. what amp alt do you have on it?? the one i had on there was a 65 amp, factory was only a 40 and i never had issues with it.

[Chuck66]

Are you sure your dash is grounded? cause if it isnt that would cause all those problems too.

[FourDoorScore]

Good call, dash was grounded, but the little voltage reducer for the gas gauge was not.

One L bracket and some sandpaper later, the thermostat now reads properly.

Gas gauge now reads empty instead of full, but may be correct, and the tank may really be empty. lets drive tooo far and find out the hard way \

RW

[FourDoorScore]

Gas Gauge reads Full when full, but somewhere between 2/3rds and 1/2 a tank is the entire range from full to empty. in the space of two miles, it fell from F down to E.

also the temp meter reads a little bit on the cold side, but this is summer in the south, so that can't be right either.

So... new gauges? or is it the sending unit in the tank? I imagine those older gauges weren't as tolerant of over-voltage or amperage, because there was an unforeseen need for more power usage.

on a side note. what is the voltage or resistance of the sending unit? I've heard that the unit and the gauge need to match up for proper calibration.

RW