Help, ideas, battery drain 79 K10 details

[chengny]

This caught my eye:

I reconnected everything on the alternator, then split the 2 wire connection on top, the lug on the drivers side (redish wire) will cause the light to go out when interrupted. The other wire on the left had no effect.

What's strange is - that, depending on the year (1979 and up) and how the alternator is clocked - if the connector plugs in at the top, the RED lead is generally either on the outboard/RH side. Or if the connector is indexed off the vertical plane, it is the lower of the two. The BRN wire connects to the inboard/LH terminal - or the upper - of the two terminals.

However, prior to 1979 those connections were reversed - RED was inboard/LH and BRN was outboard/RH.

Is it possible you have a earlier model alternator installed?

From the 1979 Service Manual and wiring diagrams:

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And 78 down:

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Don't trust me on this - but it is something you might want to look into.

 

[Mike Curtis]

I'm going to go back and confirm the wires going into the alteranator but mine is exactly as the one pictured with the brown and red wires (Terminal 1 - Brown, Terminal 2 Red, Bat to the lug on the rear. If someone has a wiring of the area showing what connects to what in one view, please post. Otherwise I'll search that today. I believe the brown wire goes to the alternator light and the red wire is suppose to be hot(12V). I'm not sure if that red wire is carrying current for everything else under the hood. If it does, disconnecting it just means I stopped the flow of power and the fault is somewhere else in the system.

Tonight is more trouble shooting. When I say ground fault, I mean I have a test light between the negative ground cable and the negative post of the battery and the test light is dim but on.

What I know for certain, is when I disconnect the 2 wires that are also connected to the same lug on the starter solenoid coming from the battery, the ground fault goes away, and, when I disconnect the 2 wires at Term 1&2 on the alternator the ground fault goes away.

The battery is grounded to the engine block and the engine block is grounded to the cab (factory connections).
I've removed every fuse in the fuse block under the dash and it does not remove the ground fault.

 

[Mike Curtis]

FOUND AND FIXED! Thanks everyone for the input and between looking at the wiring and the picture of the alternator, I discovered that when the guy put the motor in the truck for me, he had twisted the wiring harness around and force plugged the alternator in backwards. It was exactly as I described in my first post and after looking at the picture and inspecting the plug, I saw where the form of the plug had been crushed allowing it to go in backwards. So, with it in backwards, it gave me the ground fault and my test light was on when grounded to the frame, once I connected it the correct way, the ground fault went away. I repeated it several times just to make sure. Everything is back together, and the battery is charged. Unless it goes dead in a few days, I believe its fixed and the problem was found. Thanks and hope this help somebody else one day. These forums are great!

Now, on to a leaking PS pump and putting all the AC brackets and compressor back on the truck. I'll post some pics in a build thread coming up.

 

[Richard Schultz]

Check the red hot wire to the distributor,isnt between the tranny and engine bell housing?Door switches work,open door dome light comes on?