Charging issue (i searched)

I just bought an m1009 blazer. Its got 27k miles on it and i dont believe it is a roll over, the frame even still jas the origional black paint on it.. When i got it the glow plugs were t working and i found the resistor to be bad, so i bypassed it to the front alternator to get my 12v that the solenoid needs. Glow plugs are now fixed. The problem is my alternators, neither of them work and they were both replaced woth known good ones. Uesterday i spent a few hours cleaning and greasing wvery connection i could find. Still wouldnt work. My volt meter does work, my blower motor for the heater works, and my gen 1&2 bulbs both work. With the key off and the little white plug on the alts off the red wire gets12v, the exciter wore gets nothing. Key on and the exciter wire as well as the other one in the white connector both get 12v like i read on here they should. After all this i went and bought another alternator for the driver side thinking it would fix the problem. Still isnt workig... Prior to replacing the alt with the new one the gen 1 light was on all the time, its off now when running like it should, but even testing voltage at the alternator im still only getting batter voltage. Im stumped. Please help!


Ignore the typos, im on a cell phone.

Checked relays under the dash? Read the TM?

I wish I were at this stage. My truck runs but won't charge. No light comes on and no volt meter reading. I'm curious if all my wiring fused or grounded. Please let me know if you lay new cable because I am clueless as to how to get it working. Good luck to you however it gets going. I'm searching TM's for alternator rebuild kits and grounding suggestions as we speak.

I would read the tm, but like i said im just on my cell phone. I feel bad asking for help because i know its here, i just cant look at it right now. Can you tell me where the relays are? Id really appreciate it bud.

I'm not sure myself. Definitely can't recall and it's dark outside. Maybe I can help next off day.

Its midnight and im outside with a flashlight trying to figure this sucker out haha im one determined sob!

I'm at work now and can look at the TM's. The new alternator i bought was an autozone PN - DL7157. The weird thing is though, it looks identical, but doesn't have a stud for the grounds like the one on the truck did. This alternator has the stud for the little wire that just pushes on, the stud for the (+) and a screw that bolts the little capacitor down to the back of the alt. There isn't another stud on it for the grounds like there is on the one i took off. I put the ground wires to the bolt that held the capacitor down, i figured a ground is a ground. no? It seems like the truck itself is doing what it should be. I tested the exciter circuit and it seems to be working, the volt gauge is working but shows right at red/yellow. any ideas why this new alternator doesn't have the stud for the grounds on it?

Because the new unit isn't the 'isolated ground" unit. Autozone doesn't sell them.

I sure hope you didn't give them your old unit as a core.

More than likely you have at least one burnt fuseable link that needs replaced.

everywhere i looked online said you can uses the DL7157 as a replacement for the driverside alt only. I gave them an tiny rx7 alt as a core, no way there were getting my good one. I have a rebuild kit on the way. so can i use this DL7157 or not?

I really appreciate the help guys.

Yes you can use the DL7157 on the drivers side only.

If you happen to install it on the passenger side you will see some great fireworks and maybe your truck burning to the ground.

i may be new to the CUCV, but I'm not about to go tossing parts around with out knowing what i am doing first. I found that one thread that said how to test the truck wiring and it seems like my truck is working fine, problem is in the alternators. but it cant be, the two that were on it were pulled from a running (and charging) M1009 blazer. and then the new one i got still doesnt work. I dont understand how i am getting battery voltage at the alternator big red cable, power with the key to the exciter wire, and im still not charging. i guess there can be problems with the heater motor not working but mine works fine and i already cleaned every ground and wire i could find. both gen lights light up with key on, then go off when running (before i installed the AZ alt, the gen one light stayed on while running but wasnt charging) the volt meter works too, but is red/yellos. Ive installed stand alone computer systems in cars, ive wire tucked engine bays and re routed under hood fuse boxes more times than i should of. I am very good with wiring and thats why this is getting to me so bad.

You will need to check the wiring between the alternator output and the terminal blocks where they tie back into the system.

the driverside connects to the 12v terminal block next to the master cylinder and the passenger side connects to the 24v terminal block behind the rear battery.

Without knowing the condition of those wires and fuseable links we will just be guessing.

i cleaned all those wires up two days ago and greased them up good, they were pretty nasty. If there was a fusible link in that wire that goes to the 12v block by the master cyl, wouldnt i still be getting my 14.4V or so right at the alternator if the exciter wires are working?

Have you downloaded the TMs and printed outthe wiring diagrams?

I have copied each wiring diagram and saved it to my computer. When I am working on a specific item, I bring up that diagram and use MS Paint to color the wires I am working with.

Also at the begining of the troubleshooting section of the TMs you will find instructions on how to read the diagrams and what all the connections and wire labels mean.

seems like all of my fuseable links are working or i wouldn't be getting voltages to the alternator like i am. the gen lights both work, so that makes me believe the relay is good, im not sure where the DIODE is, but it must be ok because im getting voltage at the exciter wire #1 on GEN 1. i am also getting 12V at #2 wire on GEN 1 so that leads me to believe those fuseable links are good. i suppose i could have a blown link coming from battery 1 ground to negative block on the pass side firewall, that i have not checked yet.

two questions regarding the charge circuit. where does the wire go coming off of the gen 2 relay leading off of the paper and what is the "slave receptacle"?

That diagram is taken straight from the TM 9-2320-289-20 tech manual. The wiring diagrams are in appendix F of that manual. Reading the diagram says to look at diagram F-4 for the continuation of the circuit. That wire goes to another fuse in the fusebox.

You really need to start reading all the TMs. Especially TM 9-2320-289-10 Operations Manual.

Have you downloaded the TMs yet?

The "Slave Receptical" is the NATO Plug on the front grill that is used for jump starting. You plug the jumper cable into it.

The diode is for the GEN2 circuit. It is behind the dash above the heater control

I knew i had everything tested right... took the "new" alternator and had it tested. FAIL went to buy another one (i really needed this to run) and had it tested, FAIL... they gave me my money back, money for the core charge, and i got to keep on of the junk alternators for all the hassle. I went to a different store and bought one, had it tested first, tossed it on and I'm good to go. I will NEVER buy an alternator from anywhere without getting it tested first. I wasted about 7 hours of install/uninstall, driving around to parts stores, and trouble shooting in 100* weather. Thank god the charging and my GP issues are all sorted out. Now i have to figure out the fuel/air leak. Takes for ever to start and i think yesterday I heard a hissing sound coming from by the tank, i hope its just the rubber line back there. They are all 3/8 fuel lines right?

When new parts fail out of the box, it really makes it hard to diagnose. Glad you figured it out.