In the charging sensing resistor inside the gauge? For a few years I’ve had an issue with the charging system, it charges 13.5volts cold no load. And 11.5v hot with headlights and cooling fan on.. so it’s been a close to home car.. no night driving. Well recently the charging gauge dropped to 0 while driving. I took the cluster out found 2 bad spots on the printed circuit. Could this have been my issue all along?

 

No, there is no alternator bias resistor built into the gauge.

What you really need to do is get a voltmeter, doesn't need to be an expensive "Fluke" meter, a cheapie harbor freight "centech" meter will do, and check your voltage at the battery both no load (engine running of course) and with everything on (headlights, fans, wipers, etc) and report back the results. If the results are the same (13.5 no load, 11.5 loaded) you've most likely got either a failed diode, or a failed stator coil in your alternator...

PS, as you can see in this handy diagram, the voltmeter is a simple two wire device, one connection to ground, and one connection to the "gauges" fuse, with no connections to the alternator. In other words, you could remove the voltmeter from the gauge cluster and the alternator would not be affected.

 

duplicate post....

 

How do you know "it charges 13.5volts cold no load. And 11.5v hot with headlights and cooling fan on"?

Depends on what "my issue" ACTUALLY IS. If "my issue" was a gauge problem, then yes, absolutely. If it was an actual charging problem, then probably not, unless one of the "bad spots" involves the "Choke" light.

In a word, not enough info to accurately answer the question(s).

 

I meant to say, 13.5v cold whether loaded or no load. And 13.5 hot no load. But it’s drops with a load when hot. I can turn everything on and itll
drop to 10.5-11volts in a few minutes.. I was really hoping it was within the printed circuit!

 

I’ve had it running, and monitored the voltage from cold to hot several times. I did read a lot about the choke light even though it’s TPI. It’s supposedly important. And I do believe the bulbs there. I’ll go check to see if it’s good or not right Now

 

If it's TPI, there isn't a choke light.......

 

oddly enough, there is, and the bulbs there. But it never comes on, I checked the bulb, it’s good. As previously stated, it charges without the cluster. I feel this car hasn’t been toyed with too much as its all stock. Bought it from a divorced couple, the wife got the car in divorce court in 2009, was parked since 1989 in a daylight basement in lenoir, nc with 42k miles on it.. she had the dealer they bought it together at haul it off and go through it in 2012 i bought it in 2014.

 

And this is measured... HOW? ... WHERE? ... WHEN? ... WITH WHAT? ... and so forth

So, is/was this a carbed car, originally? If so, or not, what is its induction system NOW? How much has the wiring been "improved"? How much are you asking us OUT HERE, where we can't even SEE the damn thing, to just RAW WILD-A$$-GUESS at? Give us something to work with.

 

it’s a all original 1985 TPI. Wiring hasn’t been improved. It’s all original with the exception of replacement parts such as battery, cables, alternator. And it’s pretty clean. I’ve checked the voltage at the battery terminal. And at the post on the alternator. I’ve checked continuity for the brown wire to the fire wall, I’ve checked continuity from battery to starter. From starter to firewall. It’s been an issue since I bought the car… I’d post pictures but everything I have is over the data limit… I did verify the alternators part number it is a 108amp alternator. But, I had to change the pulley from v to the 5s pulley. Not sure if that’s causing an issue with alternator RPM.. these systems are rather simple… but I don’t know where that 10 ohm resistor is. I was hoping it was in the gauge itself. But that is clearly not the case.

 

Agreed 100%, , , even the finest brain surgeon might end up working on your butthole instead of your brain if the room is dark enough .....

 

Okay. Crawled under the dash. Brown white wire from IGN switch to C100 has 10.0 ohms. That’s ruled out. Checked everything else again. All checks out. Now I did some research on this and im seeing a bad reputation with the brand. Maybe it’s worth buying a different brand. I have the oreillys: Ultima 108 Amp Alternator - Remanufactured - R111666B