Wiring identification help...

[BENEFIELD02]

I have a 1986 K5 Blazer I bought in pieces and and trying to rebuild. It came with a manual shift transmission originally. I have 2 wires (Purple & Yellow) behind the gauge cluster that I am having trouble figuring out where they went. any help would be appreciated.

 

[Wes Harden]

purple and yellow @12 ga dia, normally are the clutch safety switch. The picture you posted appears to show them connected together, this is common by passing the clutch switch. If the switch were and wiring were there in working ordered the clutch peddle would need to pressed down to crank the engine

 

[BENEFIELD02]

purple and yellow @12 ga dia, normally are the clutch safety switch. The picture you posted appears to show them connected together, this is common by passing the clutch switch. If the switch were and wiring were there in working ordered the clutch peddle would need to pressed down to crank the engine

So i should not need to do anything with these as I am going to an auto? Thanks for the info!

 

[Jim 0814]

The yellow is "constant 12 V. "so, maybe you can tap off it for something else that needs 12V all the time. (If you don`t use it for clutch).

 

[Wes Harden]

wow i did not see this reply. an auto will need a different type neutral safety switch. Those two can be connected to new switch. Are you swapping to an automatic steering column or going with a floor shifter ?

 

[Jim 0814]

Sorry, neither. I just know yellow is a constant.

 

[500$k5]

Sorry, neither. I just know yellow is a constant.

Yellow is Not constant hot. This wire is hot only when the ignition switch is in the crank position. Put ign in crank position= yellow gets power. Clutch is pushed in = yellow is connected to purple. Purple goes to the "S" terminal on the starter solenoid. Starter cranks. This is also true on an A/T except yellow and purple go to a neutral safety/ back up light switch mounted to the column. The switch is on top of the column close to the floor board.

 

[Jim 0814]

Well, I beg to differ. WHY do they call it constant? Because, it has constant power to it when the key is in the "OFF" position. If you put the key "ON" the wire is "RED", also called "Switched Power". Just take a circuit tester to the Yellow wire (with the key OFF or removed) and the tester should illuminate. The reason the Purple wire is connected to the "S" terminal and cranks the engine (ignition switch ON is because it`s connected to a Red "Switched" wire somewhere in the ignition circuit. Anyway, that`s how I was taught.

 

[Wes Harden]

No the purple, or yellow for manual, wire for the crank signal has no power in the on or run position, only in the momentary crank position.
see yellow arrows. That is the 86 wiring diagram from GM

@Jim 0814

 

[Jim 0814]

That`s what the diagram shows but, why are they connected together if the yellow is for manual and purple is automatic???

 

[Wes Harden]

That shows yellow from the ign switch to the clutch pedal switch, then purple from clutch switch to bulk head connector to start solenoid for manual.
Purple from ign switch to neutral safety switch on column, then purple to bulk head connector and starter solenoid. I cropped out the switch and the starter side to make the image larger. You can see the ignition switch terminal cavity marked sol, this only has power in the crank position.

Original poster PO has the yellow and purple tied together to bypass the clutch switch.

 

[dyeager535]

*Generally* red is 12V constant (look at the wires off the battery) black is ground, and orange is 12V switched.

However. Going strictly off wiring color is a great way to burn things up. Use the manual, identify what the wire should be, then use a multimeter to ensure that wire operates as it should via the manual. Most people don't ensure they buy the same/proper color and gauge (or quality!) wire when they need to replace or add something. They use what they have lying around or which is readily found at a store.

These trucks are too old, too tampered with, and the manuals not 100%, to *think* we know what a wire is because of its color. If that was the proper way to do things, and people knew what they were actually doing, we wouldn't have the wiring messes we invariably see, such as the first pic in this thread.

People can do what they want with their rigs. Just hate seeing the nightmares improper wiring turns into.

My take on it anyway.

 

[Wes Harden]

Orange and white are usually the courtesy circuit, and hot all the time.

Yes nothing is written in stone, double check