Low and High Voltage

[TheNiceLips]

Hi everyone,

I have a bit of a head scratcher here. The other day, my '99 threw a "Check Gages" light when I used my turn signal. Oddly enough, the in-dash voltmeter dropped way down into the red (~9 V) when I first switched on my turn signal (including messing with the speedometer needle), and now every time the blinker is illuminated, it's just under that lower limit mark (maybe 12 V?). Anyways, then I turn off my turn signal and the Voltmeter goes back into the normal range (leaning slightly left of completely vertical). I also notice that when I accelerate, the Voltmeter drops a little bit, and turning the A/C system on drops it a fair amount. Although, if I'm cruising down the highway with the A/C on, the Voltmeter reads a bit above that lower limit mark.

But here's where things get interesting. I get home and grab a proper voltmeter out of my toolbox and put it on the battery posts. With the engine warm/just driven, but OFF, the proper voltmeter read 14.4V! And then I started the car and it jumped to 16.2V! I look at the dashboard voltmeter, and it's in the middle section, but definitely not close to or above the 14V mark. I then go to reproduce the problem using my turn signal, and the voltage drop occurred again on the dashboard voltmeter, with its needle moving based on when the blinker was actually illuminated, but my external voltmeter is reading 15.5V.

And here's the cherry on top, I switch on my 4-Way (Hazard) flashers, expecting twice the voltage drop because I'm using twice as many turn signal lamps/bulbs. But, the dashboard voltmeter doesn't move one bit, and the external voltmeter is still reading 15.5V!


I'm pretty good with cars, but have no idea what could possibly be the issue here. Any input would certainly be appreciated.

[TheNiceLips]

Update: just had the electrical system checked at an auto parts store. Their device measured the battery at 12.38V with the car off, and the battery at 14.4V with the car running/under load.

On my way home, I used my turn signal to merge into the highway, and the voltage drop was so severe that my speedometer was jumping up in 5 mph increments (up 80 mph indicated, despite the fact I was only doing 60 mph or so). I was driving with lights on, but A/C compressor off.

[J Wikoff]

I saw your post report. Can you post what you found to be the issue? It might help someone in the future.

[TheNiceLips]

I discovered the issue to be my aftermarket keyless entry/car alarm unit that I installed several years ago. I guess after several years, one of the leads (I believe the one running to the "On" position sensor for the ignition - the pink wire under the dash) developed a short, which is why there was such a large voltage drop, on the dashboard side, and why the battery would read fine (maybe the dashboard voltmeter uses this wire to determine system voltage?).

TLDR; If you're experiencing voltage fluctuations, check for a short in your aftermarket components.

[MKMike]

Thanks for the update.
Glad you've figured it out.