Rear batt not charging

[melbatoast]

Hi fellows, this is a great forum that I use anytime I have a problem with my M1008. Thanks for all the great info. I've always searched the forum and found my answer, but not this time. So this is my first post. My rear battery, nearest the firewall, does not charge. I have been swapping the batteries back and forth once a week which has been working, but I'm sick of doing this. Both alternators are producing around 14 volts, and both batteries are new and in good shape. Any ideas?

 

[Warthog]

Sounds like the fusible link between the GEN2 and the 24v Positive Terminal block is bad.

You will have to chase wiring.

You do have the wiring diagrams that in the New and Improved tech manual section don't you?

 

[melbatoast]

Dead on... thanks Warthog. Found the short and replaced the wires, now she's charging like a champ! -Melbatoast

 

[Warthog]

Sometimes us oldtimers hit the mark.....

Glad you found the problem.

 

[howardc]

Does it matter which bolt the rear POS batt cable is attached to on the terminal board? I have been having the same problems, rear batt not charging. I have to charge it once a week it seems, since it is my daily driver. The front batt is fine, and both alternators are working. I opened the positive terminal board last night after pulling the TM's and deciding to go through wire by wire. The POS cable of the rear battery was connected to the second bolt, not the third as pictured in the -34, diagram E-9. Also, the Gen2 cables (fusible links) were attached to the third bolt, not the second. I swapped them and they are now wired correctly according to the diagram.

Sidenote: The starter wire? was connected to the same bolt as the POS rear batt cable, so I moved it over with it, now hooked up to the third bolt. Everything else seems to be correctly wired according to diagram E-9.

Batteries were dead so I have to get them charged today before trying again tonight to see if I fixed it or just made something else worse. Any input from the Electricity Gurus would be very nice!!

 

[howardc]

I think I fixed it this time. I pulled the dash and polished the PCB with an eraser to get better contact on Gen2. I replaced a handful of fusible links under the hood, and removed and cleaned all terminals on gen2. I found a blue (10 ga?) fusible link at the pos terminal board that was brittle, like it had been cooked. Also found a blue link at the wiring harness block that reminded me of the stretch armstrong toys, the wires had no contact in the wire. Looking at the TM's it looks like both of those links go to the gen2. The blue link that goes from gen1 to the wiring harness block was ok. I went to Auto Zone (those guys know me by name) and had them test the batts and alts. Both batteries were running 14.6-14.7, which puts me at 29.3 volts. My voltmeter is in the middle of the red now, but when gen1 was the only one working, the gauge was sitting at the white tick mark in the green. I think I'll just accept the 1 volt overcharge.