Gen light issue

[Rvitko]

Searching this topic I find a few threads, but none post a resolution.

alts were both rebuilt with asp wholesale kits and hardware kits after my starter/wiring meltdown I have another thread about. Fusible links and all main cables were replaced, fuse block, grounds, terminal blocks were all stripped down and cleaned. Volt gauge is a new 24v datcom.

short drive- everything works as it should, gen lights both turn off after start, at start gauge is at the yellow/green border (this gauge has real number so 24-25v). After start, it climbs to 27-28v at idle. No issues at all in drives under 20 minutes in town.

long drive- after about 1 hr, the gen 2 light starts to strobe, volt gauge is at 28-29v border of green and red. After about 2hrs at highway speeds, gen 1 starts to do the same. If I lay off the pedal and engine returns to idle speed, both gen lights go out.

It it may be normal and related to fully charged batteries, but it is one last quirk I am trying to solve or reassure myself on. This only happens on long highway speed (55-75 mph) drives. Looking for any feedback or tips, but the batteries are new 6tmf, cables are new and professionally made, one gauge over stock. Everything seems to work right.

 

[pmramsey]

Drive 55 mph or less with only short bursts to 60 mph and the alternator light issue as described should resolve itself.

 

[Rvitko]

I should clarify this is an m1009.

The speed is plausible I suppose as it would be rpm related but on this particular drive I had a full mix of county and farm to market roads with 55 mph speed limits and a short highway run at 75 and I had about 2 miles off road. The gen lights do seem to be rpm related but once a certain distance/charge is passed only idle speed shuts them off.

 

[nyoffroad]

Sounds to me like a voltage regulator problem but it is odd that BOTH alt. do it.
Driving 55 or any speed should not have an effect on charging voltage.

 

[plym49]

I guess I would hang an accurate voltmeter on there to see what the voltages really are, and if OK then I suppose it is not a significant issue.

 

[Rvitko]

I have one hunch I am going to try, that little group of 3 capacitors on the fire wall between the hot and ground. I am kind of stickler for keeping things right and at least reversible so I made a new one myself from the proper capacitors. I am going to try removing it. I can say that this is my daily driver, I have not had this come back on, but at most I drive 20 miles a day unless I am going on a hunting or fishing trip which is when this last came up.

 

[Rvitko]

I removed my capacitor set between the 24v buss bars, no dice. The issue has gotten worse so even on short drives at low speed the gen lights come on. I do have another puzzle piece. Turning on the heater blower stops this problem. If it is on either of the lowest two speeds the gen 1 light goes off, if it is on high, gen 2 goes off as well. My first thought is overcharging and the load solves the problem, but at idle I get 14.68 volts from gen 1 and 14.75 from gen 2. My volt gauge stays pretty constant at 29-30v at all speeds. The gauge is a new 24v datcom. Thoughts? My current thinking is I have some sort of residual gremlin on the 12v side from my starter meltdown, I am leaning that way because my wiper motor struggles and stalls and it is 9 months old, at the same time I oiled the linkage with 30w oil, but maybe that has gone and I really need to get at with grease, everything else works right, I think there is some relation though because the wipers work when the engine is reved better than at idle. My electrical mods include adding a nostalgic air ac kit, a cigarette lighter, a clock, off road lights, a 7 pin trailer harness and brake controller, no splices, everything is fused and tied into a buss bar or the fuse panel auxiliaries wires are all in wire loom. The fuse box and all grounds were cleaned, the main cables were replaced and 1 gauge over stock, my only other gremlin is a very intermittent low coolant light that a new sensor and terminal cleaning did not resolve, it comes on very rarely, it came on often before new sensor and cleaning. Fwiw, blower switch and resistor are 2 years old, they were replaced and the console was removed, cleaned, new bulbs.

 

[dependable]

As suggested, it could be a voltage regulator. Another mechanic I know who maintains several CUCVs had the gen light strobing, he told me it was solved by replacing the voltage regulator, it was over charging, but it also fried the other alternator, or at least it died during the overcharge indecent. He was getting higher total voltage than 30 though.

Try setting a volt meter up so you can see what you are getting while driving at highway speed.

I believe wiper motor is on same circuit as fuel heater (in the rectangular Stanodyne mount). That caused me some problems once, short in fuel heater had caused wire insulating melt and more shorts.

 

[Rvitko]

Thanks, I have an NOS Stanadyne assembly so I will try swapping that and see if that solves the wiper motor issue and check my wiring while I am at it. I'll probably get flamed for not doing a spin on but I honestly like the Stanadyne unit.

Ugh, that will be the 3rd time I've rebuilt my alts but I think it is the most probable. I rebuilt them once and had my starter run on and fry them and had to do them again.

 

[Rvitko]

I was able to resolve this issue and it was quite simple. I had replaced the 2 pin connectors for each voltage regulator as mine were fairly corroded and cleaning didn't get me very far. In the rebuild kit from ASP Wholesale was a foam gasket square that inserts into the voltage regulator connection, they werent their initially but as crudded up as the originals were adding them seemed like a good idea. Well, on Gen 1, that gasket was preventing a full seat and contact, all I had to do was remove the plug, use a pick to move the gasket over and all the way down the socket, plug back in and no issue since and I drove my truck 450 miles since my last post as I took a 4 hr drive to a deer hunt on a friends ranch and back and the usual errands and going to work. I want to thank those who helped and while the coolant level light has been a non issue lately, I will report back once I install the new Standayne base, it has the heater and water sensor in it brand new.

 

[Rvitko]

I wanted to update this as my last solution did not last, I found that if the battery discharged a bit the strobing would go away but the excitor connections were not the culprit. In the end it was the main battery cable to the 12v buss bar. While it tested fine and looked fine, my electrical meltdown had caused a blow through of the insulation of the fusable link right at the terminal, overtime it got worse and worse until the voltmeter gauge and all accessories were strobing. I found it only by removing the 12v terminal and saw the hole in the insulation and corrosion of the wire. New fusible link and everything is solid again.