Amp meter gauge fluctuates

[rodb]

My amp gauge is fluctuating when turning on headlights, turn signals or when operating power windows, is this normal? Installed a new alternator and battery 6 months ago. Battery is charging normally. Any ideas?

 

[Bruces expo]

Yes its normal for mine , 91 Navajo , I have a newer Alt and battery and upgraded wiring and extra grounds for my previous car audio installs , and mine does the same , I get 15.1-3 Volts On a cold start and it normally makes my headlights flicker a little and makes my stock voltmeter Gauge act all sorts of funny lol .

 

[arco777]

In my opinion a large fluctuation is not normal; typically indicates poor connections at the battery terminal or internal corrosion on the battery cables/main power wires. If it is a small fluctuation like when your power windows hit their stops and the needle drops a little, no big deal, but larger fluctuations can be indicative of supply problems.

 

[rodb]

Yes it has only very small movement, so is it probably just an overly sensitive gauge? I don't know if it did that when new.

 

[arco777]

Normally turn signals do not make the gauge fluctuate; if yours do, it may indicate an issue...

 

[larrydd999]

Rodb, I'm assuming this has just started, not something that started when the alternator and battery were replaced. The voltmeter should not move more than a very small amount. It could be something like a bad ground connection between the chassis and the frame. Neither of our vehicles exhibit this. If you have a good quality voltage meter (i.e. digital multimeter or DMM) check the voltage at the battery with various loads (lights, wipers, turn signals, etc.) and observe whether the DMM voltage changes more than a few tenths of a volt.

 

[rodb]

Ok thanks, I will check the voltages as suggested.

 

[malohnes]

For turn signals to move the amp gauge is not normal, unless you all ready have a drain on the truck, like headlights, heater, defroster on etc., simultaneously. In my experience, ARCO is correct. First check the battery terminals, then go chasing down grounds and other sources for bad connections.

 

[rodb]

Checked the battery ground to chassis, it is good. At rest the battery reads 12.7, when running it is 14.8. When running with lights on voltage drops to 14.2. Noticed when running and activating turn signal gauge flickers very slightly, when power window stops at up position gauge goes from the "a" in normal to the "o" . Does this seem ok?

 

[malohnes]

No, not to me. I think the issue is not the voltage, but the current draw that pulls the voltage down. I still think you have bad connections in the battery. 12.7 volts at rest and mid 14 when running is strong, but the voltage is not doing the work, the current is. Having just enough connection to carry voltage is not to say that it is enough to carry heavy currents when on demand.

I found corrosion migrating up the wires, both positive and ground, from the battery to alternator and starting solenoid. Once replaced, this cured my power issues. I think are having a similar problem.

 

[Jason94sport]

For turn signals to move the amp gauge is not normal

Did on all mine. When the turn signal was on the needle fluctuated a little in time to the blinker. Even now with the redtop & 160amp alt it does it.

 

[malohnes]

Jason - check you wiring, you should not have any fluctuation in voltage with turn signals, especially with a high amp alternator and a good battery. Also check your grounds.

My modest stereo system, head lights and heater on full tilt will not budge the volt gauge unless the truck is shut off. Clean up corrosion and/or bad connections in the power and ground wires to chassis and battery posts should cure this. Don't judge the surface connections. Slicing the insulation back a few inches form the end and looking inside will reveal if there is corrosion migration. This is common on our trucks and MANY other vehicles too. You can reuse good wiring if you do slice the insulation back by using splicing tape (self adhering silicon tape), covered with electrical tape for strength or heat shrink tubing.

Often there is ample slack to trim off a couple inches from the stock wiring to remove corrosion. Often times, especially if stock wires, the corrosion can be present in the whole length of the wires. I find the positive tends to get the green powdery corrosion nd the negative wires tend to get a black moldy corrosion.