What are these?

[88trailblazer]

I have a 78 K10, 350/t350/203. I have to rewire almost everything on this truck. Because the prev owner half assed the build up. Can someone, please tell me what these cables go to? Right now the only gauges that work are the speed and fuel.

The 1st one is the green wire. It is live, but very weak.

 

[azblazer]

Well since i'm in the middleofthe wyoming oil patch sitting on my a-- i can take a guess. Without my library at home i can't confirm my guess.

2nd pic looks to be the type of connector body used for the wiper motor.

3rd picture i'm not so sure as it has at least five wires in it. 78's were the first year for an electric tailgate...and the entire harness changed in 79 and stayed the same till 91 when the R/V series was no more. The tail lights are going to one of the three plugs on the firewall that plug into the the main fuse panel. Also in these years you could have a manual oil psi gauge....and the harness behind the motor also had a pigtail so a electric gauge could be used also. Speedo is a cable...so its mechanical. Fuel gauge wire is purple...comes up the right hand frame rail and should be routed thru the heat shield (tube) that uses one attachment bolt on the starter solenoid and the other bolt is a bellhousing bolt. There is a green wire that goes to the left side of block for your temp gauge....and a brown wire to excite the altenator. You can remove the dash bezel....and the clear gauge cover and black cover so all you have are gauges...remove the volt gauge and use a good dvom and see if you have voltage there. And likewise with the oil and coolant if they are electric and use the ohm test....

But you really need the factory 78 wiring booklet. It lists all the ava options and color codes for each circuit. Assuming you used a test light to determine the circuit was weak..allways use a dvom with alligator clips or custome made terminals so you don't damage the terminals in the connector bodies you are working on. A test light will tell you if voltage is present...but it won't tell you how much....as the dvom will...and thats what is all important.
Also your 78 could have had cruise....but that 6 way connector does not look like a cruise servo connector....plus i don't see the bundled vacum line with harness going back in thru the firewall. The tailgate wires will plug into a grommet above the drivers side valve cover in the curvature of the firewall. If memory serves methere are only three wires which are blue-orange...and i forget the third one....but like i said the 78 tailgate wiring was a first for the blazer so it was kinda wierd like the 30 amp cb mounted on the firewall behind the brake booster...

To words of advise....make damn sure the body has the ground strap to the rear of the passenger side head....and the battery ground is to the block not thealt bracket....makes a huge diff inhow thegauge will read.

Sorry i'm not home near my book to ident some of those circuits...

Doug W.

 

[88trailblazer]

Thanks, you lost me with 3rd pic explanation because the electric tailgate would be on a k5 and I this is from my k10 pickup... But I currently have the battery ground to a header bolt (not the block) and I do not have the ground strap from the firewall connected to anything. I'll have to take of that asap.
Also that green wire in the 1st pic is probably the water temp, like you said, because I found it running along the passenger side of the engine. I just installed a new temp sender so I'll try that wire out this week.
Thanks

 

[Zeus33rd]

I believe the horn wire is also green.