Idle speed solenoid (1 Viewer)

[madinal]

My engine (79 FJ40 2F desmogged) only runs at high speed. When I push in the choke it dies. It was suggested that I test the idle speed solenoid. I do not hear a click when I turn the key to run. I do not get a meter reading between the two leads or between either lead and ground.

What voltage should I expect at the connector for the solenoid?

Where does the power come from so I may trace it back?

 

[myquestoyota]

The power comes from the fuse panel, the fuse that is designated ENGINE, second from the bottom on my '77.

 

[madinal]

So, is it 12 volts across the two leads or are there two different signals between the leads and the case ground? I'll check my fuse, though, thanks.

 

[1911]

12V across the leads. usually when the fuel cut solenoid doesn't work, it's because the emissions "computer" is not grounding it. Try grounding the white wire with the red stripe from the solenoid; if the truck idles with that grounded then the solenoid is good and the "computer" is bad (or more commonly, the soldered connection where that wire enters the circuit board).

 

[madinal]

I checked the fuse and it was good. I have no reading across the connector. I'll try to follow it to the little box behind the clutch which I guess is the computer. Thanks

 

[1911]

Yes, the computer is on the driver's side kick panel near the main fuse box. The easiest way to check the solenoid itself is to disconnect it at the carb connector, and run jumper wires from the carb connector, one to the positive terminal of the battery and the other to a good ground. Then start the truck and see if it idles.

 

[madinal]

Thanks 1911, I checked the solenoid by touching a wire to the battery and all was well. Now for some shade tree rigging. Can I just run a lead from the solenoid to the battery and keep it activated all the time or is there time when it is supposed to be off? That is until I can get into the "computer."
Thanks again.

 

[1911]

Thanks 1911, I checked the solenoid by touching a wire to the battery and all was well. Now for some shade tree rigging. Can I just run a lead from the solenoid to the battery and keep it activated all the time or is there time when it is supposed to be off? That is until I can get into the "computer."
Thanks again.

It's even easier than that - all you have to do is ground the white wire w/ red stripe for the solenoid to be activated all the time the ignition is on. Lots of folks (me included) fix it that way and leave it as a permanent fix. I just put a piggy-back jumper connector on said wire, right before it enters the "computer" box and a small ring terminal on the other end connected to a convenient bolt under the dash. Practically invisible, and removable if I'm ever seized by some strange urge to fix the "computer" in the future. If you did it your way, there always be current flowing to it 24/7 even with the ignition off.