What The Heck?

Hey guys I was cleaning up the transmission and I saw a couple items I did not recognize. I went pouring over the TSM and had no luck finding out and information. Thanks for any help I greatly appreciate it!

 

Look like switches to me, maybe neutral safety switch and backup (reverse) switch?

 

Ah great. I haven't checked the wiring diagram yet on the TSM going to give it a look over. Thanks for your thoughts!

 

At least one of those is the switch for the back-up light.

"Safety Switch?" We don't need no steekin' safety!

 

Yes the one with 2 prongs is the back up switch. The other says on the wiring diagram just "transmission controlled" both end up at the ignition at the instrument panel.

 

other = "transmission controlled spark switch"

 

Forgive my ignorance, but can you elaborate on what that is?

 

TCS is an emissions device. Controls a vacuum solenoid that retards the spark in top gear. Covered thoroughly in the TSM.

 

It sends a signal that the trans is in top gear so that the timing can be retarded and the mixture can be leaned out to conserve fuel.

 

Close. Does retard the spark by blocking the vacuum advance, but has no effect on the mixture or economy. Indeed, I would assume less advance makes fuel economy slightly worse. Later spark reduces the combustion chamber temperature and reduces NOx.

Page 4A-27 http://oljeep.com/gw/74_tsm/4A-EmissionControl.pdf

EGR affects the mixture, but that's always on at operating temperature and above idle, at least in 1974.

 

Yeah haha I would have never check emissions section of the manual. Thanks Tim