Hey guys,

I need some help with a wiring diagram that I have looked at for too long. Normally I would just grab a circuit tester and figure this out by trial and error, but my car is in so many pieces right now that isn't a possibility. My wiring harness is laying all over the inside of the car and I have no battery at the moment. I am removing the factory clock and using the left over wiring to power the AFR gauge for my wideband. To correctly install the AFR gauge I need a ground, an IGN switched 12v wire, and a headlight powered wire to cause it to dim at night. Anyway....

I am trying to decipher what each of the four wires do that connect to the clock for a 1984-1985. They are as follows:

BLACK: Ground (obviously)

RED/GREEN: Is this the power wire for the light bulb/illumination when the headlights are on?

GREEN/YELLOW: This appears to be the "switched" power source? But is it an "ignition" switched source or an "accessory" switched source? I don't understand why is this even needed if the clock is always hooked to the battery? What is it doing?

BLUE/WHITE: Is this constant hot? Right off the battery with a 15A fuse?

I have also attached the wiring diagram for the clock below from the FSM. If someone could give me some guidance here it would be much appreciated. I have looked at this diagram for too long.....

Thanks,
Jamie

 

Here's my go at it. I was an Electronic's Technician in the Navy but that was over 25 years ago so my skills are a little rusty.

Yes
BLACK: Ground (obviously)

Yes
RED/GREEN: Is this the power wire for the light bulb/illumination when the headlights are on?

This is active in Ignition and Accessory. I believe this is needed to make the display active. The constant wire, BLUE/WHITE, keeps the time when the ignition is off and the GREEN/YELLOW make the display appear.
GREEN/YELLOW: This appears to be the "switched" power source? But is it an "ignition" switched source or an "accessory" switched source? I don't understand why is this even needed if the clock is always hooked to the battery? What is it doing?

Yes
BLUE/WHITE: Is this constant hot? Right off the battery with a 15A fuse?

 

i agree.

black is ground.

red/green is the illumination wire

green/yellow switched power

and blue/white. the clock needs a constant power so it knows what time it is, but as Mr Repu says, it needs the switched power to run the display.

 

Thanks fellas! That makes sense to me. So here's another question for you guys. It has been too long so I don't really remember. On an 84-85 FB does the display for the clock work when the key is removed, or does it only display the time when the key is in ACC or IGN?

 

I just checked the clock on my GSL-SE, but any 1984-1985 would be the same, and the clock display is on even with a ignition off. This means that the BLUE/WHITE constant 12V not only keeps the time, but also drives the display when the key is in the off position. I'm not sure of the true function of the GREEN/YELLOW. I still believe it's driving the display when key on but can't be sure unless looking inside the clock.

For your use with the gauge, your assessment of what the wires do is correct and should work great.

 

I have owned my 84' since it was new. The clock is always displayed regardless of presence of the key in the ignition. I believe that the function of GREEN/YELLOW is to only allow the clock light to turn on when the key is turned to ACC or Ignition. Unfortunately, my headlights are currently stuck down so I can't go home and check my theory.