Alternator issue = Very frustrated!

[Sine Metu]

Okay to start off... when I bought my 84' M1009 the guy before me replaced the driver side alternator with a regular 100Amp from Advanced Auto. The passenger side alternator is still the original. Last week my front battery no longer was being recharged, my first thought was the driver side alternator, however when I had that tested it was fine. I also had the passenger side alternator "tested" that is once hooked up to the tester it did nothing, thus a bad alternator...

With the original alternator (passenger side) and the alternator the previous owner installed on the driver side my front battery is not charging and is at 11.7v the rear battery is 14.4v (engine running) and the whole series is 28.(something). both lights in the dash come when i turn the key to start.

So after I had the two alternators tested i purchased a new one for the passenger side, before I found out I needed an isolated ground alternator =/...I installed the same standard 100amp alternator and quickly realized once i connected the front battery terminal the wire that runs from the negative terminal on the rear battery, along the wall to the engine wire harness started to smoke. I quickly removed the positive cable from the battery, went and got the right alternator from NAPA a WIL 90014277 with an isolated ground, installed and as soon as I connected the front battery positive terminal the same wire jumps in place and heats up, it has already melted a little bit of the rubber coating but is not touching any other metal...the only way I can reconnect the batteries, is if I either remove the red wire that connects the the stud on the back of the passenger side alternator that the sound suppressor is also connected to. I can start the truck like that but none of the batteries charge. If I put the original alternator on (the one that wouldn't test and thus supposedly bad) the rear battery would charge but not the front...

Everywhere I read the driver side alternator charges the front battery and the passenger side alternator charges the rear battery... am I missing something or doing something wrong?

again both lights work fine, all my connections are correct the only thing that is not working is my front battery is not recharging...Any help would be greatly appreciated!

also if it is easier to discuss this on the phone just send me a PM and I will respond with my phone number.

Thank you very much,
-Anthony

 

[Westech]

sounds like you smoked something good. Really the only way you are going to fix it is get the TM and trace all your charging wires.
You are correct on the driver side charging the front and the passenger side charging the rear. I replaced my Driver side with a Stock GM unit and it worked fine, but like you said you needed a isolated ground on the passenger side.. NOTE... many of the NAPA units people were finding that they were NOT isolated grounds and having issues. You might want to bust out the multi meeter and take a look to see if that is really a isolated alternator.

 

[Patattack]

the right alt. charges both batterys which is spos to be 25-28v but can not go pass 30v the left alt charges the front batt. if your front isnt charging but your rear is then i check the left alt. look in the tm for trouble shooting and currect voltage. and trace the wires u may have fray a fusible link. i have a pass side alt over charging on mine and it jumped from 20v in the begining to 30v in the end so i know how u fell im think of converting to 12v. if im wrong anybody corrent me im just going off the tm.

 

[Sine Metu]

Thanks, yea I've been looking in the TM's its just so freaking confusing. I hate electrical problems...When you say left alternator is that driverside or passenger side?

 

[Patattack]

Thanks, yea I've been looking in the TM's its just so freaking confusing. I hate electrical problems...When you say left alternator is that driverside or passenger side?

my bad left is drivers if siting in the drivers seat, if u have adobe reader its pg954 in the 34 level tm for the eletrical drawling and pg 66 in the troubleshoot section also in the 34 level tm if u dont have it ill post it up for u

 

[Patattack]

oh yea then it will have the testing section in the link i forgot about that it will show u how to test the alt

 

[Sine Metu]

Thanks, yes I have that TM, I will look at it again with a "fresh updated mind" maybe I just overlooked something...I think one of the most confusing things is that if the driver side alternator is suppose to charge the front battery and my front battery is not charging, why would the alternator test at Advanced Auto say that (driver side) alternator is good?...I don't know... I'm going to put the old alternator on tomorrow and try to retest everything with my volt meter and make sure everything is connected properly.

If NAPA is notorious for this, maybe it isn't isolated. I looked at the section for test and repair of the alternator in the TM, anyone who has bought the repair kit, how difficult is it to rebuild it myself (the passenger side alternator). I knew nothing about alternators (aside from what their function is) before this so im definitely a novice.

 

[Warthog]

the right alt. charges both batterys which is spos to be 25-28v but can not go pass 30v the left alt charges the front batt. if ....... i have a pass side alt over charging on mine and it jumped from 20v in the begining to 30v in the end so i know how u fell im think of converting to 12v. if im wrong anybody corrent me im just going off the tm.

WHERE ARE YOU GETTING THIS INFORMATION......IT IS WRONG

Each alternator is a 12v alternator. When they are working properly they each will put out ~14.5v. When the voltage is combined you will have ~29v.

The driver side alternator charges the front battery and the passenger side alternator charges the rear battery.

 

[Warthog]

Thanks,....why would the alternator test at Advanced Auto say that (driver side) alternator is good?...I don't know.

The alternator can be fine but the wiring can be bad. More than likely it is a bad "fusable link" that has burnt in to.

 

[Sine Metu]

The alternator can be fine but the wiring can be bad. More than likely it is a bad "fusable link" that has burnt in to.

so Warthog, just to make sure I follow, you think that one of the charging wires/ fuseable links to/from my driver side alternator is bad?

 

[Sine Metu]

and also if it is the fusable link, than (and im sorry if this is a stupid question) how do I go about repairing/replacing it or them? I have not searched the TM for fusable link yet, so my apology for not previously looking

 

[Warthog]

and also if it is the fusable link, than (and im sorry if this is a stupid question) how do I go about repairing/replacing it or them? I have not searched the TM for fusable link yet, so my apology for not previously looking

The wiring diagrams are in the Appedix of the -34 or -20 manual. The manuals do not cover replacing wiring.

You will need to google for wire replacement. There are hundreds of youtubes that walk you thru replacing the wires.

 

[Warthog]

so Warthog, just to make sure I follow, you think that one of the charging wires/ fuseable links to/from my driver side alternator is bad?

Check the BIG red wire on GEN1 and the fusable link that is attached to the 12v Engine Wiring Harness Block that is next to the glowplug realy (or master cylinder)

Also check the BLACK ground wire that attaches to the engine block.

Have you read the first few pages of the troubleshooting section? It covers how to read and understand the wiring diagrams. It also explains how to read the wire sizes.

 

[Patattack]

oh man sorry sine metu my bad i was looking at the m1010 guide not the m1009 thank u for correcting me warthog on that they are 14.5v, just go in the eletrical diagram and looking for that bad link i seen one almost right off the alt if u peel the eletrical tape off and heat protective covering there will be a differnt color wire on it and the wire will say fusible link on it its just finding the needle in the haystack, i also hate eletrical problems, but i wander why the diagram says both carging and front charging do u know what that meens warthog?

 

[dependable]

Alt 1 circuit runs though heater blower fuse, not sure if this is in TM. check post Batteries dying in my cucv.

 

[Sine Metu]

Thank you all for the input and help! I fixed the problem!! The driver side alternator which when tested at Advanced Auto and tested good was the problem, not sure why it tested good but when I bought a new one and replaced it, the front battery was charging at at 14.5volts with the engine running! it cost me $111.(something) with $11.55 core charge.

Thanks again!

 

[dunedigger]

I didn't take the time to read this whole thread but had to add this. I bought a wilson alt from napa and burnt up my truck. Turns out they were selling isolated ground alts that really were not. It's a simple continuity check from the ground screw to the case to be sure it's isolated, I didn't do that. I assumed it was what it was. I spent 6 months personally making it my mission to get wilson to pull these and stop building them wrong so this didn't happen to anyone else. It never worked. I can't tell you how many alts I had shipped to napa and dealing countless hours on the phone with wilson. In the end it was for nothing. They can not build an iso alt. They can't even find the right size nuts to go onto their own studs. Wrong threads. I've never been so angry at a company. sorry for the rant, a lot of time wasted on them.

 

[Friar Mycgyver]

I have also had problems with my generators and haven't been able to find an exact replacement. I did however find a rebuild kit. alternatorparts.com part# D15027 $26.95 includes new brushes and springs, diode trio, regulator, front bearing and rear bearing along with instructions on how to replace the bearings. They also have statues and field windings should you need them.

 

[Friar Mycgyver]

I forgot to mention that when you are looking for parts for your generators you want to specify that it is a delco remy 27-SI / 100 type. When cross referencing part numbers look for delco remy part number 1105500.

 

[Friar Mycgyver]

They also have stators not statues.