Another mystery plug

[broncoswede61]

I've owned my bronco for 10 years now and never thought to ask what this plug is.(center of throttle linkage)

 

[broncow72]

I may be wrong but I think that goes to your H block for the "BRAKE" light.
Is yours hooked up?

 

[72Sport]

I've owned my bronco for 10 years now and never thought to ask what this plug is.(center of throttle linkage)

Part of the emission system. I think it had to do with vacuum advance control solenoid.

Actually it is part of the "Transmission Regulated Spark Control System. The system includes the ambient air temp sensor on your drivers side door post above the top hinge. There is also a switch on the transmission to sense when your transmission is in high gear. The plug on the firewall supplys power to the deceleration valve which cuts off the vacuum advance when the ambient air temperature is above 65F and the tranny is not in high gear. Better said your vacuum advance does not work unless you are in high gear and the temperature is above 65f. Below 49f the system is off and it runs like a real car.

 

[Eoth]

I've owned my bronco for 10 years now and never thought to ask what this plug is.(center of throttle linkage)

Hair Dryer...

 

[broncoswede61]

Part of the emission system. I think it had to do with vacuum advance control solenoid.

Actually it is part of the "Transmission Regulated Spark Control System. The system includes the ambient air temp sensor on your drivers side door post above the top hinge. There is also a switch on the transmission to sense when your transmission is in high gear. The plug on the firewall supplys power to the deceleration valve which cuts off the vacuum advance when the ambient air temperature is above 65F and the tranny is not in high gear. Better said your vacuum advance does not work unless you are in high gear and the temperature is above 65f. Below 49f the system is off and it runs like a real car.

Ah ha....Thanks Jerry....now it's all coming together Do you have yours hooked up?

 

[fireman1749]

Mines unhooked also

 

[72Sport]

Ah ha....Thanks Jerry....now it's all coming together Do you have yours hooked up?

No I don't. When I first bought my Bronco I rebuilt the engine and took it to a shop to make sure it would pass smog. Smog checks were required then. The shop person said don't worry about. If it was him he would take the stuff off because no one would know it was supposed to be there anyway. I saved it but as the shop owner said no one knew it was missing. I never failed a smog check.

 

[broncoswede61]

No I don't. When I first bought my Bronco I rebuilt the engine and took it to a shop to make sure it would pass smog. Smog checks were required then. The shop person said don't worry about. If it was him he would take the stuff off because no one would know it was supposed to be there anyway. I saved it but as the shop owner said no one knew it was missing. I never failed a smog check.

Yeah I remember when I first got my Bronco it did not have anything resembling emissions equipment left on it....my first smog check cost me an extra $20 slipped under the table;D

 

[broncnaz]

I know the blue plug is hooked to the throttle solenoid on my 71. I dont think I have the bigger plug also I didnt see anything in my wiring diagrams what color are the wires?

 

[72Sport]

The bigger plug is a black wire and my diagram shows it going to the caburetor solenoid. My carb solenoid is now part of the ac system. I found my book The smaller plug which I think is below the big plug it is for the transmisson regulated spark control sensor switch. I borrowed both of them for other things. I can't see the smaller one cause I have it all taped up.

Broncow72

The h-block wire is taped up with the large plug and seems to be in the same loom.

My book doesn't show the spark control system on a 71. It is shown on the 72 and 73 wiring diagrams. My book only goes to 73.