My car starting running rough at the end of a 100 mile trip last weekend. Among other things the Autometer tach starting reading incorrect rpms. The car wouldn't start after I turned it off, so if figured alternator bad, fuel pump and fuel injection not getting enough juice causing it to run poor. So I had the alternator checked, failed test. They did not have the correct one, let alone a chrome one so I replaced the internal voltage regulator and took it back, passed test, everything ok... Except the voltage gauge points straight down now? Can't think of how I did not hook something back up?

Any ideas how I can fix this?

Pat
70 SS396

It's possible that you reversed the polarity to the gauge somehow. That depends on how deep you went into the wiring before you found the bad alternator.

Do you have a multimeter? If so, check the voltage at the inputs of your gauge. If you're meter shows good voltage, but your gauge doesn't, it's time to replace the gauge. Check for reverse polarity while you're at it. If you aren't getting good voltage to the gauge, then you need to trace the wires back. If you don't already have a multimeter, you can buy little cheap analog meters at Wal-mart or some parts stores for $10 or less. It's a good tool to have.

Chad

My amp gauge does this about every other crank. It's as if the current draw or charge that sudeenly takes place pulls the needle around 180 degrees.

I can usually turn the headlamps on and then hit the brights, and the needle rotates around another 180 back to the top center.

Any ideas out there why this would happen?

You did not say what kind of car you have but it does not matter. All ammeters or current meters work the same way. They dependent on voltage.
Suspect that you are having large voltage changes. Check the voltage out of the alternator. Is it dropping down below 13.5 volts? Have someone pull the lights on while measuring the alternator. Still staying up there?
Check the connections and voltage on the shunt resistor. Everything tight?

His signature says he has a 70 so I A.S.S.U.M.E. that's the car he is talking about.

My 70 does the same thing http://www.chevelles.com/forum/confused.gif

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Dean Call
Team Gold member #3
A.C.E.S. # 00235
N.C.O.A. # 4350
Mid America Chevelle Club (http://macc.chevelles.net) #001
chevelles.net (http://chevelles.net)

[This message has been edited by Dean (edited 02-19-2000).]

Sorry, I don't see any reference to a 70 Chevelle. The days are perfect in southern Califoria and only have some evenings.
Since nobody is providing help, I'm trying. Still have not heard back if this is occuring only at idle or all the time.

I do appreciate the all comments and help. Yeah it is a 70 Chevelle SS396. Original 402 block etc. The alternator is a chrome aftermarket unit. It is working fine now, I checked it with a meter, and the battery is charging but the guage points down. Sounds like I am not alone. It worked fine till the recent alternator problem.

Pat

Add the Bomber to the list of Chevelles with strange guage readings. Sometimes the tach goes a little crazy, kind of random in occurance. Now the voltmeter is more of a mystery. When I first got the Bomber, the volt meter had no reading, then one day it just upped and started working, and stayed working up until a few days ago. All I did was adjust a loose fanbelt, and then the voltmeter once again went into hibernation. Its most likely a loose connection, I checked for that with nothing amiss. I'll have to get out the multimeter to diagnose.

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"Bomber" '67 El Camino
Beater comes back to life
350/TH350 14.90 @ 93mph!

I think the car(s) really have an ammeter not a voltmeter, even though the face says volts. I don't have a schematic for a gauge model 70, only one with lights. If someone out there has an assembly manual on a 70, check it out. If there is a shunt resistor in the circuit the gauge is an ammeter. Need to know what it really is. I'll look around for an answer if nobody shows up. It decided to rain here anyway.