Hi, I have a 1995 K1500 with the 5.7L engine and am having issues with the reading from the dash voltage gauge. I have a brand new battery and alternator, both tested good at autozone, and when I hook my multi-meter to the battery while its running I get a reading of about 14.7 which tells me the alternator is working. Battery reads 12.6v after the vehicle is off so it is charged. For whatever reason though the volt gauge on the dash is only reading like 11-12 when I first start it, which eventually it moves to the 13-14 range but if I have my head lights on and turn the heater on, the guage drops down rapidly back to around 11, but sometimes goes back up to 12-13 ish, sometimes 14. But with all those things on I still get a reading around 14.5 on my multimeter hooked directly to the battery while its running. Lights do not seem to dim but this still makes me nervous seeing the gauge drop like that. I am running out of ideas as to what the issue may be.

 

Don't be nervous. The gauge is probably just misreading because it has a loose connection or ground somewhere.

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It's nothing to worry about. A true fix would be to change the alternator until you find one that has a better low rpm output and excite rpm. Or build one. Find a local alternator shop and get a better voltage regulator.
From my experience and your explanation, sounds like the alternator's not exciting at low rpm's ( low gauge after starting, at idle) and low rpm output, hence the low gauge reading with high load demand....

My issue the same, high load, low speeds, low gauge reading. I have a '98 C2500 Vortec 5.7L. Aftermarket alternator from one of the big 3 auto parts...

It is what it is.

 

frost i think you missed the part where he said no matter what the reading is at the dash his multi meter still reads 14v at the battery. meaning the alt is properly charging but the gauge isnt receiving the proper volts or its a weak gauge.

so does the battery light ever kick on or is it just a gauge issue?

 

I have virtually the same problem (With the batt lite on as well but only above 1100rpm. Lite is off @idle!)
Voltage at alt. and battery and cigarette socket 14.6v but dash gage never gets to 14.
suspect loose connection at instrument panel?
But not sure how that effects the idiot lite?
1wire alt testing good, batt testing good.
94 Silverado 5.7
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The voltmeter receives system voltage through the ignition switch when the key is on. At the gauges fuse, see what you have for voltage with the engine running - if it matches system voltage, the next step is to pull the cluster to test for voltage and verify ground at the IPC connector.

 

I'm not sure if your year vehicle uses stepper motor gauges or not, my 05 Trail Blazer does. I wouldn't worry too much about the dash gauge if you have good readings with a VOM at the battery. On e-bay you can fin little instrument cluster repair businesses, (Rock Auto, too) if the problem is that annoying. The stepper motors are repairable, and you might find the parts with a little searching. Plenty of off shore alternators have a hard time at low rpm. You might consider a quality (Auto Meter or other brand) under dash voltage gauge as an alternative to instrument cluster surgery.

 

I dealt with that for years on my 95 K1500. Worried the crap outta me thinking something was wrong. Anything that was turned on in that truck resulted in flickering voltage. Well I ignored it for a long time. It became the normal. This weekend I upgraded my gauge cluster to the 1999 Cadillac Escalade cluster because it shows 120mph instead of 100. Easy swap. Anyways. My volt gauge now is like new. No flickering and reads the same as multimeter. Even tho you may not want the Escalade cluster you can find one like yours for $20-$30

 

I just bought a 95 suburban and it's doing the same thing I was wondering myself b4 spending 💰💰 and listening to the wife nag I bought the family you know a POS.thanks in advance

 

@Turbo tim try the troubleshooting in this thread, and post your results in a new thread in the the suburban section.