Amp meter guage with a mind of its own....any ideas?

[mpdlawdog]

OK, here we go again with another problem in my charger....I put a radio and amp in my car to run some 6x9s in the back...everyting was fine for a few weeks..then the fun started...the amp guage would dance in the positive side with the music....now the guage is dead center with no movement...the radio keeps turning off and on....any ideas what might be going on?  Thanks in advance.

everything else works including the other guages, lights....
the radio is wired to the origional "radio" wire in the fuse box
the alt and battery are new

[Nacho-RT74]

I guess you hooked your new stereo system on the batt side... with an ammeter system that's wrong. That means ammeter is reading like alt is charging the batt what is not true, actually is feeding your stereo/amp system. Thats an unnecesary stress on amm. EVERYTHING on a system with an amm on the line must be hook to the alt side, no matter where in the line, but on alt side ( black side of the ammeter ). Thats why all the sources are spliced from there as you will be able to see on diagrams

an small reading about how an amm works and what does mean the reading ( and a nice upgrade if you care ):

http://www.dodgecharger.com/forum/index.php/topic,33574.0.html

( now everybody will tell you bypass the ammeter and blah blah blah, what is not necesary making the right corrections and checkings but it's up to you )

check the wires and terminal conditions at bulkhead and on back of ammeter. If car keeps on without missing on power and
Radio is missing it could be the red side of the amm somehow weak. The alt keeps the car on because all the power is being taken from that side from factory but something is being miss on the batt side, thats why the ammeter is not getting the reading to the batt side.

the ammeter is not an alt gauge like factory stated or made us think, it is actually a BATT gauge.

a CHARGE reading when you are running it means the batt lost juice and is sucking back the power to get balanced his electrochemical balance, untill is full. The ammeter is sensing that power being suck by the batt.

when you get a discharge reading, it means the alt is not able to feed everything on the car ( at certain RPMs ) so the missed power, what alt is unable to feed is being taken from the batt. Then revving up you'll get the oposite reading since alt is being able to feed the system PLUS what batt missed up on previous status... This PLUS to the batt is what amm reads. The power being sourced by the alt is never getting read

[mpdlawdog]

thanks for the reply...looks like I will have to do some tracking down....

so if the battery was low on a charge, (when it was running and the radio on)  it would show in the positive side until it got charged up?  would that explain why it was doing that (in the positive side) and now it stays in the middle?  Where should I hook the radio up at?  I used the factory wire off of the radio.  The amp is hooked up from the battery.

[Nacho-RT74]

ON A PERFECT BALANCED SYSTEM the ammeter must be death center because it means the alt is feeding everything around without need a batt support on a fully loaded batt. Thats the PERFECT DEAL to have.

if you get a CHARGER reading it means the batt OR SOMETHING on batt side is sucking power and ammeter is sensing the power going to batt side. On this case, you have the amp being sourced from that side so the charge reading could mean the amp requirement allong with maybe some of the batt being charged back for some batt unloaded at certain moments, pretty much normal on any car, just that amm cars registers that.

when you starts up the engine, you will have a charger reading ALLWAYS... to recharge what was discharged by the starter motor on cracking. This get last long for some minutes depending on the alt capacity, RPMs and the car demand requirements at the same time of the batt recharge. Let's say at night, the recharge will be longer due the car demans more power coming from alt to the stock equipment.

on these moments the alt capacity at lower RPMs is the critical problem. All Mopars are on this deal due the stock alt unneficiency. The more juice from alt at low RPMs ( closer to idle as posible if not at iddle ) the best performing you'll have everywhere and healthy recharge system.

If you don't have an amm reading EVER, something is wrong. ITS NORMAL get discharge and charge readings. As stated all cars have at certain moments that status just that ammeter cars registers that and ammeter uses to be a weak point specially if is not tight and clean. The problem is how long and how big is the reading. The smaller reading and shorter time, the better for ammeter cars.

actually the better for ANY car, just that on ammeter car is more sensible because the gauge.

[mpdlawdog]

Ok so I got a chance to mess with the car. I took all of the wiring for the radio and amp and checked it and made sure all the connections were good. I drove into town 10 minute drive  the amp meter was in the middle. It didnt move. When I pushed on the brakes the radio would go out. So I tried the turn signals. Same thing. I made it to town  was there for an hour or so. Started the car and the amp gauge worked it showed postive 20 and went with the music  at idle it was center.  
I assume the gauge is bad. I had a friend with a 68 who had a simlar problem. He took the two wires on the amp gauge and put them together. He then hooked up a battery gauge and ran it under the dash to make sure it was 12 amps  would this work?  I don't want to burn my car up!
The car has stock everything minus the radio.

[Nacho-RT74]

you can get good conections on Radio and amp, BUT NOT the main ssytem what sources everything on the car

an ammeter its allmost imposible to get damaged so easy, unless burn and in that case it is noticeable.

the battery gauge your friend hooked must be a voltimeter, so registered 12 volts.

Check the BULKHEAD conections, thick red and black wires

hook both wires together on back of ammeter doesn't mean you are fixing IF the problem is somewhere else... it can be a fix OR not

[mpdlawdog]

Thanks Nacho...I will check them when I get home.....how do you know if the guage is bad...I smelled what smelled like hot wires when I got home.....would this explain why the meter is "stuck" in the middle and only works part of the time?

[dodgechar]

  may try auxlary fuse box for you tunes,  wired  from the battery hot.  this bypasses the dash wiring. takes the load off the dash harness.  wired my electric antena there too.   easy to get to.  still need a good charging system.  alternator, battery.    most problems are related to the bukhead connectors.  especially in wet areas. 4o years of vibration.

[mpdlawdog]

here are the pics I took.....
1 is at idle (where it was stuck it seemed)
2 is moving

I will wire another fuse box for the radio.....what guage wire should I run from the battery to the box?  Thanks again.

[Nacho-RT74]

wire from bat is wrong keeping ammeter

[mpdlawdog]

"wire from bat is wrong keeping ammeter"  Not sure what you mean Nacho...

OK so I finally got a chance to look at the car...I put the radio on a separate fused link off the battery...I went to start the car...it fired and shut off....turned the key ....nothing....I looked at the bulk head wire and the black wire on the starter rely melted in the bulk head...I got under the dash and looked at the amp gauge...it has a red wire coming off the left side a black wire going off the right side and a red wire stuck on a post in the middle...there is also a brown wire with the same connector as the red wire attached in the center on the back of the gauge....I am going to "hot wire" a line from the starter bypass the bulk head and put a fuseable link on it...then attach it to the red wire on the back of the bulk head....will see....if anyone has any other ideas let me know....

[Paul G]

First off, your 45 year old wiring wont handle an amp. Over loading the system in stock condition will burn the wiring. Don't let that stop you though, it never stopped me. To add accessory's safely you really need to replace the wiring from the alternator, straight through the bulkhead connector, and splice it in to the harness where the original wire soldered in at. Do the same thing for the wire from the battery/starter relay, straight through the bulkhead connector, and splice back in to the existing wiring where the original wire connected. The main problems with the system are the small size of the original wiring, and that very crispy 45 year old bulkhead connector. There are a lot of threads with great pictures showing how to do this, you can search "bulk head connector".

I just did my 72 this way. I used 10 gauge wire, cut open and discard the tape on the wiring harness from the alternator, and the battery/starter relay to the bulk head connector, remove the old wire, replace it with the new 10 gauge wire. Use a new fusible link at the starter relay. I separated the bulk head connector halves, pulled out the old burnt copper pins, to make the opening big enough for the new wire to fit through I drilled through the cavity in the connector the old wire went through, one cavity for the alternator, one cavity for the battery wire, plugged the bulk head connector back together and ran the new wires right through the it. You could solder or crimp the new wires to the same locations the stock wires went and be done, or do like I did. I installed a new auxiliary fuse box. It had a stud on the top to make the connections. I brought both new wires, alt and batt, to the stud, and connected the old wires under the dash that used to go through the bulk head connector for the alternator and the battery, to the same stud on the new fuse block. This will make the amp gauge useless. And it will not be stock if you are in to that. I added a volt meter under the dash to keep track of my charging system. Tape up the wiring harnesses similar to the factory job and your done. I feed my A/C compressor clutch and idle solenoid, electric cooling fan, radio, and the electric exhaust cut outs from the new fuse block. Lights stay bright, voltage stays up even with the A/C running. Best mod I did to the car, almost.   

Nacho has great drawings for this.

[mpdlawdog]

Thanks..I am going to disconnect the amp for now until I can get this figured out......I already started on the wire straight through the bulk head from the starter relay so it will by pass the bulk head...I didnt think about the alt wire.....it is a small wire....any idea where it leads to past the bulk head?  Is there only one wire that goes from the alt to the bulk head that I have to replace? 

I just figured out (Im gussing...) what part of the problem was...the wire on the interior side of bulk head was redone at sometime with a 12 guage wire....were it was "put together" at the bulk head is were it melted...I ran a wire through the bulk head to the wire so I think I will be good there.....the alt side is still origional...Im guessing its feeding back some how because of the difference  :shruggy:Thanks for the idea! 

[Nacho-RT74]

please check the link I posted and you will know...

for a while I explain better what you didn't get: when you have an ammeter on a car, to take power from battery is not right. Will get wrong ammeter readings and unnecesary stress on it

[mpdlawdog]

OK...got it!  Will look at it tomorrow....Thanks for the help!