Did the factory make this mess ??

[Johnl48]

Originally Posted by Steeveedee

The only difference would be the crimp connectors in the OP. I don't think that GM used them?

The wires with the yellow crimp in op were added. The junction box wires appear factory

[chewychevy67]

Yes my 67 has the extra terminal boxes by the volt regulator. They aren't in the exact spots yours are though. No idea what they are for.

[Grumpy old man]

Ok , This is driving me nuts The digging I've done leads me to believe it's a harness for dual batteries / OEM Auxiliary Battery (RPO TP2) or a custom camper harness to enable adding dual batteries ?

[chewychevy67]

My 67 did not have dual batteries. This is how mine is wired. Thicker Red Wire from the fender junction block goes to a merger of 3 red wires and a black wire with a 4 amp fuse ( i believe is for the amp gauge). One to the alternator, one to the regulator and one to the block on the left . There is a back wire in between the 2 blocks on the rad support ( possibly a fuse link). Then after that block their is a thinner red wire that feeds power into the fuse panel plug. I'm not sure why they did this bit it's factory.

[Johnl48]

I don't know what it's for but I put it all back as per assembly manual

[HO455]

The two insulated terminals and the associated wiring were installed as part of the high output alternator package. Our trucks as delivered didn't need more amperage than the stock 37 amp Delcotron unit provided. However GM recognized that some customers may need to add accessories to their vehicle and in order to avoid warranty issues around battery charging they designed the harness to allow these extra loads to be easily hooked to the system without compromising the battery charging system.

With the 37 amp system the alternator output, battery charge wire and the supply wire to the truck's wiring are crimped together inside the engine harness where the driver's side fender meets the core support. This connection is not visible without cutting the harness apart. See photo below.

On trucks with the higher output alternators the 2 insulated terminal blocks are added to the crimped wires in the. So if you need to hook up an electric pump for a snowplow, motor driven siren, high powered 2 way radio or need to charge a dual battery set up you would simply hook new the load to one of the insulated terminals without having to cut the harness open. This will ensure that the alternator senses the load correctly and the battery wouldn't over or under charge. In addition the factory amp meter would still work as designed.

I've attached an excellent article on how GM alternator systems work to help explain what is going on.

http://madelectrical.com/electricalt...evymain1.shtml

After thinking more on this it may that the black jumper wire between the two terminals was removed for dual battery systems. Where one terminal would go to the second battery and the other one for the accessory loads.

It would be nice if someone with an unmolested truck or a dealer publication that could confirm this.

[chewychevy67]

The second battery I know nothing about but the 67 has a different style alternator than the 37 amp unit as well so that would support the need for more power at the terminals. It has a 62 amp alternator rpo k81. I am currently restoring this truck and had these parts restored already . That is why they look new but they are a original and a nos unit.