1972 Jeep Cj5 T15 Trans - What Is This Switch For?

I have a 1972 CJ5 with the T15 trans 3-spd. I know the one switch on this trans is the reverse light switch, but I cannot find in my manual or looking at schematics as to what the other switch is for. Anybody know, as it needs to be replaced if I knew what it was.

 

Transmission controlled spark (TCS). It's in the TSM in section 4A.

 

I think it’s an emissions switch, the other is back up lights

 

Transmission controlled spark switch!

 

You guys are funny. Will keep looking

 

For what ?
Two folks have told you what it is.
I'll be # 3.
Transmission controlled spark switch.

 

Seriously, it's in the manual like Timgr said. It's an emissions control system to retard the spark in lower gears for reduced NOx. A simple Google search for "Transmission Controlled Spark" shows it was commonly used by Ford and GM in the 70s too.

Here's the page from the Jeep manual:

 

It's even in the '72 TSM:

 

that sounds like piston return springs, but i guess it's a thing. ya learn something new everyday.

 

Piston return springs are in the Engine Maintenance section of the TSM.



These are for the 232 however the 258 uses similar springs.
They are color coded for different compression ratio.

 

wut? thats a thing?

 

Not trying to argue with anyone, but this jeep does not have one single vacuum switch like shown in the diagram. It is also a 304V8. It is entirely possible that whatever it hooked to was removed long ago.

Timgr, I have also tried to find a TSM for this 1972 Jeep CJ5, but looked all over RockAuto like you mentioned a CD was available and many other jeep sites, If you could send a link to a TSM for this 1972 Jeep CJ5, I would certainly appreciate, because I need one so I don't have to ask these types of questions.

Anyway, I certainly appreciate all the feedback and am learning as I go with this first jeep.

 

1972 JEEP CJ5 5.0L 304cid V8 Repair Manual | RockAuto

Not Haynes.

 

Tim, Thank you very much for that. They both looked like good manuals to own so I ordered both of them. I already had the Haynes manual and it is not much help but those two Detroit Iron look like just what I need. Thanks again.