List of electrical connections that are unused or unplugged (and whether they should be that way).
This has come up a number of times both recently and over the years. Electrical connectors that aren't plugged into anything. Is it supposed to be that way? Why? What was supposed to go there? Do I need it?
I thought we could compile a list of these connections along with pictures, parts manual page reference, part number if applicable, and an explanation of why it is like that (or what is supposed to get plugged into it). After everyone has had a chance to add to the thread, myself or someone else if they're so inclined, will put it all together into a forum post or PDF file as a resource here.
I thought we might be able to group some of the connections according to manual versus automatic transmission variations as well as by car evolution or chronology. Some of the unused connections are meant for automatics and so manual trans cars don't need anything plugged in there. Others were changes to the car as production went along, like provisions for heated mirrors or to reduce radio interference.
Here are some of the ones I've had in mind:
The WOT (wide open throttle) switches on the throttle spool. The automatics use two switches (and so both of the connectors) while the manual cars use only the one. The switch all cars use is the microswitch with flap one (p/n 102784). The second one that only automatics use is the microswitch without flap one (p/n 102785). The confusion that can come is that all cars have both connectors on the engine wiring harness regardless of transmission. These connectors have been called the "Tetris puzzle piece" looking connector and are located just above the throttle spool. The connectors are dedicated and have separate wiring colours so it does matter which one you plug in for each microswitch.
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Also relating to the automatic transmissions, underneath the shifter plate, there is a small lightbulb which lights up the PRND21 bar. This lightbulb is not needed on the manual trans cars, but the wiring is still there. I do not believe the bulb receptacle is there, but the wiring to power it is. It tends to be taped over and wrapped out of the way.
Here is a photo of the lightbulb on the automatic and the approximate location of where that same wiring would be on a manual trans car:
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