Did the factory make this mess ??

[Johnl48]

Is this how the factory mounted all these junction boxes on the radiator support ? Pic of yours ??
Thanks
70 C20

[57taskforce]

I don’t believe the factory made that mess. Mine had/has nothing more than the voltage regulator and wiring and the horn in that general area.

[Steeveedee]

Nope, not with that style of crimp connectors.

[Johnl48]

Phew...thanks

[FirstOwner69]

The factory did as shown in pics below. You probably don't have the 12 gauge red wire. It's part of the factory camper wiring option. I'm not sure of when the factory moved the washer bottle to the fender.

[Johnl48]

Originally Posted by FirstOwner69

The factory did as shown in pic below. You probably don't have the 12 gauge red wire. It's part of the factory camper wiring option. I'm not sure of when the factory moved the washer bottle to the fender.

Wasn't sure what all those junction boxes were for. What is that black disc on the lower left ? Mine didn't have that

[FirstOwner69]

Originally Posted by Johnl48

...What is that black disc on the lower left ? Mine didn't have that

High note horn option.

[Johnl48]

Thanks

[57taskforce]

Those red wires taped to the harness do not look factory at all to me.

[Grumpy old man]

None of that red wire belongs there , The factory didn't crimp wire ends that way and I'm more interested in WHAT all that mess is feeding power to ?? Aftermarket fog lights ? I'd start by chasing the wires to see what it's sending power to ?

https://www.youtube.com/watch?v=nW_TtiNDSI0

[Johnl48]

Originally Posted by Grumpy old man

None of that red wire belongs there , The factory didn't crimp wire ends that way and I'm more interested in WHAT all that mess is feeding power to ?? Aftermarket fog lights ? I'd start by chasing the wires to see what it's sending power to ?

https://www.youtube.com/watch?v=nW_TtiNDSI0

The truck is being restored I'm in the process of cleaning up the harness and putting it back in. Only thing I saw was a trailer brake.
The photo was taken before I stripped the truck

[Johnl48]

Originally Posted by Grumpy old man

None of that red wire belongs there , The factory didn't crimp wire ends that way and I'm more interested in WHAT all that mess is feeding power to ?? Aftermarket fog lights ? I'd start by chasing the wires to see what it's sending power to ?

https://www.youtube.com/watch?v=nW_TtiNDSI0

The red wires going to the blocks look factory. They are coming out of the harness

[HO455]

Was your truck a fleet or commercial truck? The SPID should indicate a larger alternator. Like K76 or K81?

The truck I parted that had those terminal blocks was a ex-Weyerhaeuser fire response Suburban. The factory provided those terminal blocks for fleet or commercial customers to hook up their aftermarket accessories for correct voltage sensing by the charging system.

I have been unable to find any kind of wiring diagram that shows the extra wiring for these larger alternators.
If yours still has the original 61 amp style alternator it should look like the one below if it is a 67-68. I've only seen this set up on 68 and earlier trucks.

The wiring in your last post looks like what I've seen before in trucks that came from the factory with higher output alternators.

[Johnl48]

Originally Posted by HO455

Was your truck a fleet or commercial truck? The SPID should indicate a larger alternator. Like K76 or K81?

The truck I parted that had those terminal blocks was a ex-Weyerhaeuser fire response Suburban. The factory provided those terminal blocks for fleet or commercial customers to hook up their aftermarket accessories for correct voltage sensing by the charging system.

I have been unable to find any kind of wiring diagram that shows the extra wiring for these larger alternators.
If yours still has the original 61 amp style alternator it should look like the one below if it is a 67-68. I've only seen this set up on 68 and earlier trucks.

The wiring in your last post looks like what I've seen before in trucks that came from the factory with higher output alternators.

It does have a k76 61 amp code on spid.. not sure what the truck was in its previous life

[Johnl48]

[Johnl48]

Look what I found...guess they were factory

[Steeveedee]

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

[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.