alternator help please

[cobia2017]

I feel like my alternator issues never end...currently I have an issue where alternator 1 is not correctly/fully charging battery number 1.... Alt 2 is charging battery 2 as battery 2 reads 14.6 while truck is running, however, interestingly, I cannot get a voltage reading at the excitor plug on alternator 2. The execitor plug on alternator 1 reads 11.5v on both the red and brown (when on) wires. Battery number 1 only reads 12.5 volts while running and will increase to 13.5v with a few seconds mild engine rev, but with morning work commute with lights and heater, battery 1 voltage will diminish and require trickle charging during the day. The dash lights are working (both gen lights) and the heater fuse is working as well. I did change the alternator 1 to a know good alternator and same problem, no changes for better or worse, which leads me to think its not a bad alternator, rather some wiring issue. I changed the battery to rule out the possibility of a bad battery, but the battery is not the culprit either. So, I have to assume its in the wiring. Any and all help is appreciated.

 

[WWRD99]

Dang you're having a bad week!! Is this a new problem since the glow plugs or did it do this before...ugh...I think when I was going through some weird stuff with mine I found using the alt sticky that are written up and go step by step as it says just to make sure I didn't miss anything. Drivers side should have a ground wire on the back then to the spot by the water housing...other than that making sure connections are clean and wires aren't burned.

 

[cobia2017]

Dang you're having a bad week!! Is this a new problem since the glow plugs or did it do this before...ugh...I think when I was going through some weird stuff with mine I found using the alt sticky that are written up and go step by step as it says just to make sure I didn't miss anything. Drivers side should have a ground wire on the back then to the spot by the water housing...other than that making sure connections are clean and wires aren't burned.

yea its a recurring problem but this time sort of followed the glow plug stuff, thanks I'll re review those threads as they are helpful for sure. I may too use this opportunity to go ahead with the Roscommon 12V conversion number 2, which at least seems simplified for future troubleshooting

 

[WWRD99]

I'd suggest a nice long low charge on each battery for a few days just to top them off...even with a new one they really like that...2 or 6 amp..it won't fix the charge issue but at least they'll be topped off good...I gotta get the small solar panel thing for all mine yet...help keep them going when they sit.

 

[ezgn]

I feel like my alternator issues never end...currently I have an issue where alternator 1 is not correctly/fully charging battery number 1.... Alt 2 is charging battery 2 as battery 2 reads 14.6 while truck is running, however, interestingly, I cannot get a voltage reading at the excitor plug on alternator 2. The execitor plug on alternator 1 reads 11.5v on both the red and brown (when on) wires. Battery number 1 only reads 12.5 volts while running and will increase to 13.5v with a few seconds mild engine rev, but with morning work commute with lights and heater, battery 1 voltage will diminish and require trickle charging during the day. The dash lights are working (both gen lights) and the heater fuse is working as well. I did change the alternator 1 to a know good alternator and same problem, no changes for better or worse, which leads me to think its not a bad alternator, rather some wiring issue. I changed the battery to rule out the possibility of a bad battery, but the battery is not the culprit either. So, I have to assume its in the wiring. Any and all help is appreciated.

Have you pulled the plastic electrical plug connector out from the alternators and cleaned the black goo out that is sometimes found in the original connections? Better yet, just replace the pigtail connector if it looks gummed up.

 

[cobia2017]

Have you pulled the plastic electrical plug connector out from the alternators and cleaned the black goo out that is sometimes found in the original connections? Better yet, just replace the pigtail connector if it looks gummed up.

Are you referring to the execiter plug? I not not sure what the pigtail is…but no I haven’t cleaned anything up so I will

 

[antennaclimber]

Check the fusible link wire at the 12v connection on the fire wall labeled ENG WRG HARNESS BLOCK
It should be the Orange to smaller Red wire connection. They can look good, so remove it and twist tug and pull on it some to ensure it is good. Then test it with an ohm meter for continuity.
It may be a good idea to remove and check the Heater fuse and clean all of the connections. I usually replace any older fuses to eliminate a possible issue.

 

[ezgn]

Are you referring to the execiter plug? I not not sure what the pigtail is…but no I haven’t cleaned anything up so I will

AC Delco professional PT2288 alternator pigtail $7.77 at Amazon

 

[cobia2017]

AC Delco professional PT2288 alternator pigtail $7.77 at Amazon

Awesome thanks just ordered it

 

[cobia2017]

Check the fusible link wire at the 12v connection on the fire wall labeled ENG WRG HARNESS BLOCK
It should be the Orange to smaller Red wire connection. They can look good, so remove it and twist tug and pull on it some to ensure it is good. Then test it with an ohm meter for continuity.
It may be a good idea to remove and check the Heater fuse and clean all of the connections. I usually replace any older fuses to eliminate a possible issue.

View attachment 861718

I will most

Check the fusible link wire at the 12v connection on the fire wall labeled ENG WRG HARNESS BLOCK
It should be the Orange to smaller Red wire connection. They can look good, so remove it and twist tug and pull on it some to ensure it is good. Then test it with an ohm meter for continuity.
It may be a good idea to remove and check the Heater fuse and clean all of the connections. I usually replace any older fuses to eliminate a possible issue.

View attachment 861718

I still haven't checked that fuseable link on account of time yet but I will, new issue: changed alternator to new one while old one was checked at shop and was checked out ok except voltage regulator needed rebuild and was done, new alternator (number 1) became super hot, too hot to touch so I parked truck...11.5 V going in at execitor and 12 v at terminals...today, put other alternator 1 on (with rebuilt voltage regulator) and same thing (too hot to touch) and same voltages...neither are charging battery number 1 consistently...that is ill get 13.5 for a few minutes only to fissile out to less than 12.6, so ineffective battery charging...also, both alternator 1's squeal horribly like metal on metal screeching

 

[antennaclimber]

Start the truck and verify that the GP relay is not applying voltage to the glow plugs after the proper time. It sounds like the GP's are still on.

The squealing and getting hot are both indicators that it is putting out all it can current wise. The GP system can draw 100 amps when all the GP's are on.

The proper NAPA relay is the ST85. It is rated for a much higher current, the ST81SB appears to be a much lighter duty relay and has been know to fail in the closed mode.

 

[cobia2017]

Ok I will most definitely do this...so the big amp draw may be cancelling out the alt charge? this makes sense as this all started when I replaced glow plugs and that gp relay and removed the GP resistor...I was suspecting something to do with the fact that the way i bypassed the gp resistor was to wire using the 12V bus on firewall to the gp relay but that also uses alternator wire connectors on same stud

 

[vanaisa]

Start engine and remove + wire from GP relay? Then it is sure that glowplugs are not on.

 

[antennaclimber]

Start engine and remove + wire from GP relay? Then it is sure that glowplugs are not on.

That is one way to test it, but I read on a few other vehicle forums, that the NAPA ST81 relays have been known to fail in the closed position.
So removing the control wires will not disengage the relay contacts.

It would be best to confirm that the wires going to the glow plugs do not have voltage on them with a test light or voltmeter.

 

[vanaisa]

This was my brainfart, i am not very wise in morning true, voltmeter is better choice.

 

[cobia2017]

sure enough like you suggested, voltmeter read 12-ish V at glow plug relay at connection going to GP's when it should not be...so I got and put in the ST85 relay and some but not all things improved....the GP's no longer are on after truck starts and the alternator 1 charges battery 1 to about 13.8 which is an improvement BUT the alternator still got super super hot/too hot to hold my hand on it for more than a few seconds and this occurred with truck running for about 3 -5 minutes...i noticed some "chirping" sounds from alt 1 but didn't drive down the road so not sure if it screeches yet, turned truck off on account of the alternator 1 heat...also, I checked the fuseable link as per the diagram you sent and it seems ok and intact...I get about 14 V at the relay going to the alternators with truck running and also I'm wondering if the resistor bank being out has something to do with this? At the 12V bus terminal on the firewall, I get about 14V at both studs and on the drivers side stud is both blue alternator fuseable link wires as well as the "bypassed" resistor wire going to the GP relay-is this perhaps too much amperage going to alternator 1? should I replace the resistor now that correct ST 85 relay is in place? Thanks

 

[cobia2017]

put resistor back in and GP relay stopped working showing no voltage to GP when wait light is on and truck will not start, tested voltage at top of relay and its 25 volts so I suppose resistor is not "resisting" voltage from 24 to 12...so back to napa for a new relay and I still no idea as to what is making the alternator so freaking hot...I feel like a dog chasing its tail

 

[MarcusOReallyus]

put resistor back in and GP relay stopped working showing no voltage to GP when wait light is on and truck will not start, tested voltage at top of relay and its 25 volts so I suppose resistor is not "resisting" voltage from 24 to 12...so back to napa for a new relay and I still no idea as to what is making the alternator so freaking hot...I feel like a dog chasing its tail

Whoa!

Hold on!

With the resistor in place, and the GPs NOT TURNED ON, you should measure ~25v at the top of the GP relay. That is NORMAL. That is CORRECT.

When the GPs are turned on, you should measure ~12v there.

That's right, Same place, two different voltages can be correct. It depends on whether the GPs are heating or not.


Please check out the GP theory of operation in the Helpful Threads sticky (top of the forum) before you start buying parts. You are jumping around, and that's going to leave you frustrated and confused.

 

[cobia2017]

with the help of everyone and in particular some crucial helpful phone calls with antenaclimber, the problem was narrowed down to the GP card under the dash, I’ve removed this card and can start the truck by short grounding the GP relay, now the alternator 1 charges battery 1 to 14.6V and it no longer gets scorching hot and it no longer makes screeching or chirping sounds, the glow plugs seem to be operating correctly as well, next step is to order a new card from hillbilly wizard…i did read numerous threads and sticky’s but obviously could use rereading them…thanks everyone