How do I install and amp gauge? - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
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post #1 of 9 (permalink) Old Sep 11th, 00, 02:07 PM Thread Starter
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I've done searches for this but it is still unclear to me. I have a '69 Camaro with TPI, electric fuel pump, and all sorts of other wonderful battery robbing accessories. The amp guage never shows that my battery is charging -it's always a few amps into the draining. I have the two main post-type terminals connected to the car battery, but then I also have several connections to screw-type connections on the battery (computer, stereo amp, etc). I have an older style alternator with one large primary wire and a plastic two-prong plug.

I was hoping someone could explain to me where I would want to connect the amp guage? Or what should I check to get this thing working correctly?
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post #2 of 9 (permalink) Old Sep 11th, 00, 02:44 PM
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The amp gauge shows current flow to and from the battery, not actually the flow in the system. The alternator usually makes current for all the acc. and ignition and extra charge as necessary for the battery. You have to put all the current flow to and from the battery through the gauge, except the starter motor and sometimes the horns. To do this you have the big cable going to the starter with no other current connections at this terminal on the starter. Then you run a good sized wire to the + term on the battery back to the amp gauge terminal. The other gauge term. goes back out to the battery area and connects to all the current feeds to the car, and the big wire from the alternator. No wire connects to the battery except the big starter wire (regular battery cable) and the wire to the amp gauge.
It's really hard to come up with an actual diagram since the wiring has been changed over the years. The big problem with all this is you may have some pretty big current flows through the amp gauge if the alternator goes out or if the battery is low. Also it is hard to fuse or protect the wiring for the amp gauge as it would need a 100 amp fuse or so, and if the fuse blows or get jarred loose you lose battery connection, not good. All in all, a voltage gauge is a better deal I think. Anyway, you need to route the wiring so all the system is on one side of the gauge, and the battery on the other. If the gauge reads backwards, reverse the wires.
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post #3 of 9 (permalink) Old Sep 11th, 00, 03:37 PM Thread Starter
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Thank you, that's what I needed to know. Time to tear into my dash and rework most of my electrical now. Ever want to smack the previous owner of a car before?
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post #4 of 9 (permalink) Old Sep 14th, 00, 03:38 PM Thread Starter
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Alright...I love you guys and I need your help. I finally torn apart my car and here's what I found out tonight: http://www.members.home.com/hoy01/test2.jpg

All the wires show in black are actually red wires. So...here's my problemS starting with most important:

1. Car won't start using turn key, replaced ignition switch already. What else could be wrong? Horn relay? When I turn the key to the start position the "GEN" light doubles in brightness. I just CAN'T get power to that damned purple wire for the life of me.
2. Amp gauge shows the battery always draining. I think I understand that the guage is in the wrong place in the system. (It awlays reads -5 or so, and it isn't backward cause the blinker will make it drop off even more. I don't know how to check the voltage regulator, could that be a problem?
3. Constant drain on battery from somewhere...but that's not too important.
4. Alternator sounds like a supercharger. (Just in case that is in anyway related.

So you guys hate me yet? I really hate seeing my car torn apart like it is now so any help would be great. I guess I just want to get the thing to start using the turn-key and get the amp guage reading right.

I'm gonna go back out and dig some more...someone save me please!

[This message has been edited by Dan-69rallysport (edited 09-14-2000).]

[This message has been edited by Dan-69rallysport (edited 09-16-2000).]
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post #5 of 9 (permalink) Old Sep 14th, 00, 03:50 PM Thread Starter
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one more thing I just remembered...I took the top off of the horn relay and notice a little black wire connecting near the top, but the other end was cut...not sure where this goes...a really tiny wire though. When I hit the horn the relay click, but I don't have the horns hooked up. Just in case this relates at all......
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post #6 of 9 (permalink) Old Sep 15th, 00, 01:08 PM Thread Starter
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Okay...here's what I THINK needs to be done to get the amp guage reading correctly:
<A HREF="http://www.members.home.com/hoy01/new.jpg" TARGET=_blank>http://www.members.home.com/hoy01/new.jpg
</A>

That shows how I want to splice the red wire coming off the ign. sw. back together and then run new lines for the amp guage. This would place the guage in the middle -between the battery and the rest of the system, as Tom said. Does anyone see any problems with this???? I was thinking I could run the computer from the terminals on the Horn Relay and leave its (the computers) grounds still hooked up to the battery, is that a bad idea?

As for the no-start problem...screw it. As far as I can tell the purple wire from the starter plugs into the ign. switch on top of column right? The purple wire coming out of the ign. switch doesn't put out anything at all when key is turned to start position though. So I don't know...maybe it's two different purple wires alltogether. Ah well...at least I'm learning a lot though...heh.

I'd sure love to get this amp guage working correctly.

[This message has been edited by Dan-69rallysport (edited 09-16-2000).]
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post #7 of 9 (permalink) Old Sep 16th, 00, 11:09 AM
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Before doing more cutting, do a search on it in this section.

Hit the search link on this page, search on Ammeter.

If you are trying to make your factory amp guage read correctly, you should NOT run power through it like a normal amp guage.

The Camaro factory amp guage reads amps by reading differential voltages from two places on the cars electrical system. So it's really a VOLT meter that is calibrated in amps.

A regular amp meter measures two voltages before and after a SHUNT, usually the SHUNT is attached to the rear of the ammeter and looks like a little bar or strip of brass.
So the ammeter is measuring the difference in voltages before and after the SHUNT.

Think of the shunt as a resistor that will cause a very small drop of voltage from one side to the other.

The factory guage uses the Camaro wiring harness as the SHUNT. There is no shunt attached to the back of the meter. If you try to pass high amps through the factory ammeter you might burn it out, but probably it would just not pass any amps through it, as it has very high resistance.
It would be like trying to take pass all the car's load through a test light bulb.

On a stock Camaro wiring harness, the power comes from the battery using a small lead from the + terminal. It attaches to an insulated block attached to the radaiator support near the battery. It then leads to the horn relay and then splits to the fuse block, voltage regulator, and alternator.

There are fuseable links near the horn relay that can burn out. They can partially burn out and pass low amounts of current but fail when a higher load is applied.

I'm not shure where it goes from there but there are basically two halves to the fuse block, one for ignition, one for accesories. I think there are two separate sections on the ignition switch for each half to keep them separate.

The clipped small black lead near the horn relay might be for a small capactior to reduce alternator whine.

Do the search, I think you will find a lot of info.
David

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[This message has been edited by davidpozzi (edited 09-16-2000).]
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post #8 of 9 (permalink) Old Sep 16th, 00, 12:44 PM Thread Starter
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Hey David thanks for the response. I should've been clearer on the amp guage that I'm using. It is an aftermarket Autometer gauge.

I'm interested in that small black wire you said that might reduce alternator whine...funny that mine whines like nothing I've ever heard before.

So you think the aftermarket gauge will handle the load of the entire system? It has massive terminals on the back of it.
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post #9 of 9 (permalink) Old Sep 16th, 00, 05:51 PM
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Personally, I'd use a volt meter. It's easier to hook up and tells you if it's charging or not. If charging, volts will be over 14. If discharging, volts will be below 12.
You just need one wire to go to the battery + lead and a ground to chassis.

An ammeter should work like you show on your diagram. But keep the wires from getting cut or damaged.
David

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