Digital gauges anyone? Question about the voltmeter.

[Happyfunballs]

I have a Dakota Digital setup in my 67 and I'd like to know if anyone's voltmeter fluctuates. Mine will go from 14.5 (above 1400 rpm) to 10.6 under load at idle. Seems to me a huge swing in voltage. I recently rebuilt my 10si alternator and upgraded it with 140amp(three wire) innards and I've tried a red top and blue top optima with the same results. 4ga monster cable ground wire from frame/body/engine and I'm convinced(based on numerous readings) it can't be a faulty ground. It never stalls and it seems to run fine, but honestly, it's buggin me.

[Yelcamino]

I have Dakota Digital in both cars and never had a problem like that with either. I did have an issue with the water temp gauge in the El Camino, but it turned out to be bad contact between the sending unit and intake manifold.

[Happyfunballs]

That's not the answer I was hoping for. Do you have electric fans? Which accessory wire did you use to power your DD brain? Hell, I get a .2 V drop when my turn signals are on. Electrical gremlins aren't fun. Thanks for your reply.

[TheJDMan]

Where are you measuring this voltage drop? I would test voltage across the battery terminals and see what the battery is actually reading at the time you have the low reading on the gauge. Could be a number of problems compounding the issue between the battery and gauge.

[Happyfunballs]

I don't recall trying that(surely I did?!). I'll do that this evening and report back. The biggest voltage drop is from the heater blower motor. The DD module displays the volts as read from the accessory wire that turns it on. Perhaps I have the wrong accessory wire? Thanks for your reply.

[Yelcamino]

That's not the answer I was hoping for. Do you have electric fans? Which accessory wire did you use to power your DD brain? Hell, I get a .2 V drop when my turn signals are on. Electrical gremlins aren't fun. Thanks for your reply.

Yes, twin electric fans on both cars. I'll see the voltage drop when both fans are running, a voltage drop when the A/C compressor is engaged (on the Elky), .1 or .2 with the headlights on, no drops from the turn signals.

I can't remember which specific wires I used, but they're both powered through the fuse box and grounded to clean spots under the dash.

[Happyfunballs]

I certainly have something happening then. Thanks very much for the help.

[Happyfunballs]

Checked the battery voltage at increased idle. 14.4. Turned on the heater blower motor and the dash voltmeter read 11.2 but the but my meter on the battery read 14.2. Verified continuity to ground all over the car with good results. Seems very odd to me. Maybe I didn't select the correct accessory wire.

[TheJDMan]

You definately have a voltage loss somewhere in the system. The most likely problem spots are the wire connections in the harness. Good luck, this will likely take a while to track down. Start close to the battery and work out testing each wire and connection.

[Happyfunballs]

Sounds good. I plan to start with the accessory wire I've used. Thanks for your responses. Sometimes it takes a village.

[Blevinator]

Did you call Dakotas tech support?

[Happyfunballs]

I did. He told me I had a loose ground somewhere.