fj40 4speed---sensor on top?

[olddodge]

my 4 speed trans has a sensor plug on top of tranny with a one wire connector. don't know what it is--any suggestions appreciated thanks

 

[brian]

reverse lights

 

[Catfish28]

What he said.

 

[Fast Eddy]

A '78 also has a high-gear indicator that feeds into the emissions computer, in addition to the reverse light switch.

 

[lostmarbles]

A picture to match the words (courtesy of Danny/ @pngunme):

 

[Fast Eddy]

When I swapped my h42 to an h41 I swapped the top cover over to retain that little guy.

 

[65swb45]

If my understanding is correct, it is a last-ditch override that, even if all other thermal switches have told the computer to let the vac advance thru to the dizzy, will still not let vacuum complete the circuit unless you are in 4th gear. That being the case, your motor would be a lot happier if you found that wire in the harness and grounded it.

 

[olddodge]

A picture to match the words (courtesy of Danny/ @pngunme):
View attachment 1244264

 

[olddodge]

thank you all! thanks for the detailed pic Tom

 

[Fast Eddy]

If my understanding is correct, it is a last-ditch override that, even if all other thermal switches have told the computer to let the vac advance thru to the dizzy, will still not let vacuum complete the circuit unless you are in 4th gear. That being the case, your motor would be a lot happier if you found that wire in the harness and grounded it.

I'm pretty sure my '78 has a vacuum retard dizzy. I have a bb in that vacuum line.