Fuse Box / Voltage Regulator Electric Help

[Dan_P]

Running into an electrical issue and looking for any guidance. Few issues have come up, so this is kind of a messy post.

I installed a Dakota gauge. All went smooth and it seemed I had no issues.
I dont drive the truck a lot, and after a couple weeks I noticed the voltage was bouncing around (on the Dakota display) when at idle. Wasn't stuck on a consistent voltage but almost constantly bouncing up to 16V+. The voltage would return to normal (~14V) if if I reved the engine and brought up the RPM.

Voltage regulator looked to be original, so I installed a new voltage regulator.

After the new voltage regulator was in, the car started right up. However voltage still bouncing up to 16V at idle. Again, rev the engine and stabilizes around ~14V.

New problem arises. When I rev the engine the voltage regulator makes a loud a whine. My friend felt the voltage regular and said it was vibrating and it seems clear the noise is coming from the new voltage regular. So I turn off the car, and the car wont stop. Take out the key, car still on. I pull the coil plug to kill the engine.

Now the Dakota gauge remains powered at all times. Without key in. Like it's on constant power fuse.

Anyone have experience with this voltage regulator whining issue? I've got a 6mo old Alternator. Probably original ignition switch.
Any leads to the car staying running even when key is pulled?

To power the Dakota I used fuse jumpers to tap into fuses with 12V constant power and accessory power 12V (only when the key is turned). Testing the fuse box now with a multimeter it seems like almost all fuses are constant power. Does anyone know what fuses should be constant power (without key turned)? Seems like way more fuses with constant power than I remember. Attached pic shows the voltage (green circles) that I'm reading with the car off/key out. (Figuring this might help me triangulate if something has gone haywire).

 

[6872xtc]

I would start with checking the last two things that you worked on, the gauge cluster and the voltage regulator.
Unplug one at a time and check to see of the ignition hot fuses drop power.

Is the voltage regulator still external to the alternator?

 

[Dan_P]

Good recommendation. Yes, it’s an external VR.

anyone know if there is a schematic that shows what fuses are supposed to be on constant power? The 6v fuse seems weird, didn’t realize there was a 6v one?

 

[ashman]

Good recommendation. Yes, it’s an external VR.

anyone know if there is a schematic that shows what fuses are supposed to be on constant power? The 6v fuse seems weird, didn’t realize there was a 6v one?

Yeah, just google 67-72 chevy wiring diagrams. There are several that show everything.

 

[Dan_P]

I reinstalled the original voltage regulator. This fixed a few issues:
- No more loud whine from the VR
- Dakota display turns off when the key is turned off
- The hot fuse issue (same point as bullet two) returned to normal

Still experiencing a couple issues:
- Sometimes the car stays ON even when key is turned off and removed. I'm able to get it to turn off by hitting the gas a couple times.
- Voltage still jumps around when at idle (~14 but bounces up to 16+ randomly). Voltage stabilizes at ~14 when driving or higher RPM.

I'm getting another new VR to see if that addresses the voltage issue....seems like the VR isn't working properly. Maybe the other replacement was defective?

No plan for the staying on issue yet.

 

[bp71k5]

The staying on issue may be power back feeding into the ignition from the alternator. I had to add a diode on one of the wires when I switched mine over to TBI or when I took out the aameter and used a voltage gauge instead (can’t remember which it was), but I wonder if something similar is going on with yours.