It's a top gear switch, with spade connectors instead of the bullet connectors on the reverse switch. It's used with the vaccum advance system, so there is no advance in 1st, 2nd or 3rd, only in 4th gear. This is an emissions part & was introduced in 1976. There are also temp senders in the head & vaccum canisters on the inlet manifold, as they only wanted the system to work after the motor warmed up. Easiest fix is to run a vaccum line straight from the carby outlet to the distributor, because ADR27a has been superceded & is no longer enforced. Don't use the top gear switch as a reversing light switch, either, as the reverse lights will be constantly on, except when you put it in reverse.

Top: 4th gear switch
Bottom: reverse switch



In some countries it is used as a signal to cut vacuum advance.

it is a top gear sensor and yes it was put into sunny's, my ute had it as well but when i changed it over for a fresh build gbox that had the neutral sensor in it i just didnt hook the plug up as it only changes the fuel mixtures in the stock carbys

i think some sunnys had them for some pollution thing in top gear from memory.

it has the revers switch then a switch down the end of gearbox where the tailshaft enters. i dont recall having it on my original 74.

All 120Y came with 56A gearbox.

Quote:In 1973 to comply with ADR 27/27A.

Gearboxes have
* Reverse Switch
* Top-gear Switch (some)
* Nuetral Switch (some)

Which two switches does your gearbox have?

my 74 120y has a differant gear box in it. A 4 speed with 2 eletric sensors and No 56A on side. when did they start putting pollution gear on Aust 120y's as i am told this is why the second sensor on housing. any ideas what this box has come out of