Voltage Gauge wiggle w/ turn signal normal?

[aa909]

Hey guys, quick question

I've got a 2014 BDR and just had the engine rebuilt and reinstalled. Running down the check list after 100 miles to make sure everything is working properly (so far so good).

But I noticed the volt gauge needle on the dash will wiggle back and forth about 0.3 volts when the turn signal is on (FYI the needle stays pinned at 13.5-14V at idle and 14.5V when driving without the turn signal on). I never paid close attention to the Volt gauge when driving so I can't recall if this is normal or if I have a ground issue somewhere after reinstalling the engine.

Thanks in advance for your feedback!

[patrickt]

Originally Posted by aa909

But I noticed the volt gauge needle on the dash will wiggle back and forth about 0.3 volts when the turn signal is on (FYI the needle stays pinned at 13.5-14V at idle and 14.5V when driving without the turn signal on).

It is either: a) Perfectly Normal; or b) The voltage regulator (VR) is having trouble keeping up with the load change of the signal filaments blinking on and off. The most common reason for voltage (and current) fluctuation at idle, causing a wiggling or "wavering" needle, in these cars is a poorly grounded voltage regulator. A lot of VR mounts on our cars are on fiberglass, which is a pretty shi**y ground. Do this test: With the engine idling, put the turn signal on and watch the needle waver. Then run an alligator clipped wire from a known good ground to one of the corner bolts that holds the VR down. If that fixes it, make the ground permanent. Try that first before we explore other alternatives.

[aa909]

Originally Posted by patrickt

It is either: a) Perfectly Normal; or b) The voltage regulator (VR) is having trouble keeping up with the load change of the signal filaments blinking on and off. The most common reason for voltage (and current) fluctuation at idle, causing a wiggling or "wavering" needle, in these cars is a poorly grounded voltage regulator. A lot of VR mounts on our cars are on fiberglass, which is a pretty shi**y ground. Do this test: With the engine idling, put the turn signal on and watch the needle waver. Then run an alligator clipped wire from a known good ground to one of the corner bolts that holds the VR down. If that fixes it, make the ground permanent. Try that first before we explore other alternatives.

Patrick thanks for the quick reply. Here are some pics of the wiring on my alternator:





First pic shows the ground from the engine to the chassis. The alternator has 2 red wires, one I can trace back to the solenoid on the starter, the second is hidden under wiring mesh but I don't think it's the ground. Is it possible the ground is wired in there?

Am I missing something?

thanks again for everyone help!

[patrickt]

Alternators usually have a ground connection, labeled as such, on the back just like BATT, FLD, or STAT. But not always. And they usually take their ground from their bracket bolt to the side of the block. Snap a pic of the manufacturer's label on the Alternator. You know, like Delco-Remy Model #12345, etc.

And you can't really tell just by looking at a ground whether it's any good or not, or whether you need another one somewhere else. You have to measure the current and do voltage drop tests, which all are very easy to do once you learn how. FWIW, I have more than one ground and continued adding grounds until the current that was passing through each ground cable was down to an amperage level that I liked to see. On the other hand, the car ran fine, and the lights and fans worked fine taking their ground connection off the frame, with only a single 10 gauge ground wire from the head to the firewall/frame. But on the third hand, my amp gauge needle started wavering after a good 10+ years of never doing that. It was cured by adding an additional ground wire to the voltage regulator case to supplement the little ground wire that was in the harness.

[aa909]

Originally Posted by patrickt

Alternators usually have a ground connection, labeled as such, on the back just like BATT, FLD, or STAT. But not always. And they usually take their ground from their bracket bolt to the side of the block. Snap a pic of the manufacturer's label on the Alternator. You know, like Delco-Remy Model #12345, etc.

And you can't really tell just by looking at a ground whether it's any good or not, or whether you need another one somewhere else. You have to measure the current and do voltage drop tests, which all are very easy to do once you learn how. FWIW, I have more than one ground and continued adding grounds until the current that was passing through each ground cable was down to an amperage level that I liked to see. On the other hand, the car ran fine, and the lights and fans worked fine taking their ground connection off the frame, with only a single 10 gauge ground wire from the head to the firewall/frame. But on the third hand, my amp gauge needle started wavering after a good 10+ years of never doing that. It was cured by adding an additional ground wire to the voltage regulator case to supplement the little ground wire that was in the harness.

Hey Patrick

I googled the part # on the back at it's a Powermaster. here's the wiring diagram online



Looks like the small wire is just the "idiot light" on the dash if battery stops charging. The larger red wire goes to the solenoid or battery and I'm clearly missing the ground wire.

So what gauge ground wire should I get, 10 gauge? and can I piggy back it on the same ground on the chassis shown in the post above (the one that goes from the engine to the chassis)?

Interesting that this diagram shows the "ground as optional"

[patrickt]

"One Wire" alternators like yours do not have external voltage regulators, so you don't have to look for one. I see on the instruction a little bolt hole for a ground strap but I don't see that connected on yours. But that doesn't necessarily mean your alternator isn't sufficiently grounded. To answer that question, put your Volt/Ohm meter on the lowest voltage setting. Then start the car and turn on all the lights, fans, and anything else you have to create electric load. Have someone rev the engine to 2500 RPM and put one lead of your VOM on the negative terminal of the battery and the other lead on the outside case of your alternator. If you read more than .2 volts (or -.2 volts if the leads are reversed) then you need to run a supplementary ground to your alternator.

[NROTOXIN]

What's 300 millivolts between friends?

[ERA 626]

normal dont worry about it...

[aa909]

Originally Posted by ERA 626

normal dont worry about it...

Thank you for that, Appreciate the input! I took some pics of the alternator wiring (next post) to see if this is correct

[SBSerpent]

Off topic. Out of curiosity, what is your ground clearance with that oil pan?