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I’m with you it screams bad ground. I have two ground cables going to the alternator. The original one and a new one I added a year ago. Both go to the grounding stud on the engine block. I tightened that thing two or three times. Even wire brushed everything. That said, I’m gonna do it again. When everything you think it is isn’t what it is then you have to do things you don’t think it is. Hope that made sense.
Scarily enough, yeah, it did.
Is there a cable that goes from the block, to the battery??
The only reason why I have two ground cables going from the alternator to the ground stud on the block is because I decided to get a new cable (forgot why). When I hooked it up I noticed the other one was buried in a loom and not worth digging out so I just kept it there. Maybe I'll take that new one I added and reroute it to the battery neg terminal just for grins to see what happens.
Took one of the ground cables going from the block ground to the alternator (left the original one alone) and routed it to the neg batt terminal. Batt now has two ground cables going to the block ground. Went to fire up truck...failed twice (cranked for a nanosecond and died) before firing up on the third attempt. Voltage dash gauge still shakes. Put rerouted ground cable back to the way it was. Removed nut on block ground stud, cleaned everything again, retightened. Gauge still shakes.
PICTURE GALLERY (as you can see, I have lots of grounding) Tell me if anything looks suspicious to you.
This is my engine block ground stud after I took off all the cables. Looks OK to me.
This is my NOS voltage regulator & associated relay. The left side mounting bolt secures a ground connection to the relay. The upper right ground mount goes to the negative terminal on the battery. The lower right ground mount goes to a ground stud on the alternator.
Alternator. The ground stud on the left accepts a ground cable going to the regulator mount AND a ground cable coming from the block stud. The ground stud on the left also accepts a ground cable coming from the block stud.
If the battery is fully charged, what you are seeing might be the voltage regulator kicking in/out.... Maybe leave the headlights on for 30 minutes, so the battery is kinda low, and see if the condition goes away.
If the battery is fully charged, what you are seeing might be the voltage regulator kicking in/out.... Maybe leave the headlights on for 30 minutes, so the battery is kinda low, and see if the condition goes away.
Well worth a try HY. I'll crank em on and mow the back lawn while I wait.
Well, that was an interesting experiment. Lights on for exactly 30 minutes as prescribed. Fired up truck. Dash needle far closer to the 8 than the 18...unusually to the left. It wasn't dancing either but it took a slow but steady climb (about 10-15 seconds) before settling where it normally sits. Lights still on, needle nice and steady. I turn the lights off and it immediately goes to dancing around again. Turn the lights back on and it steadies up. Repeat several times...same thing. Steady with lights on, dancing when lights off. Never saw that before.
So with a load on it, it is stable.... Maybe it is the voltage regulator again....
It sure seems that's what it's telling us, huh? I have to run out in a little bit so maybe I'll take a bit of a ride and check it out again (once the batt gets fully recharged). Lights on, lights off. Wax on, wax off. Rinse and repeat. And maybe do your experiment again.
BTW, I have another NOS voltage regulator on hand so wouldn't take long to swap it out if that's what I do. I guess I remain curious HY. I've gone thru two aftermarket (presumably Chinese) regulators and now this NOS regulator. Kind of begs the question...are these regulators causing the problem or is something else (alternator) causing the regulator to go bad?
