My choke magnet just recently stopped functioning. the only thing i can think of is i removed the whole rats nest minus the solenoid for the trailing ignition advance. 1980 model.

 

Choke hold magnet is driven direct from the ECU, based on the signal from the #1 coolant temp sensor on the rear of the water pump which is input to the ECU.

 

unplug/remove this sensor and the choke won't stay out.

 

Not really driven by the ECU. Blue/white wire goes direct from the #1 water temp switch to the choke magnet. Black/white wire to the #1 water temp switch gets 12V from ignition switch. When the water is below 158 degrees #1 WT switch closes, 12v goes to the choke switch magnet terminal and the magnet is energized. Above 158 #1 WT switch opens, no 12v to choke magnet. If you connect a wire from + coil terminal (ign 12v) to one terminal of the #1 WT switch and another wire from the other terminal to the appropriate terminal on the choke magnet the choke magnet would work like normal.

 

So anything else to investigate? I did just rebuild the engine so i had everything disconected. Time to bust out the multimeter.

 

So most likely a faulty water temp switch\ broken switch wire... i swear the magnet energized on the first startup of my rebuild.

 

Beg to differ, sir... on a US-build 1980, the Choke Magnet V+ lead (BrR) goes from the choke connector B-09 straight to pin K of B-01, the ECU connector. The other, black lead from the magnet goes to ground at X-15.

Likewise, both leads of the No 1 water temp switch go to pins D (the LB lead) and O (the BL lead) on the ECU, via B-10 (switch connector) and X-01 (engine harness connector). The BL lead also splits off in the body harness to go to the Hot Start relay.

There is no direct connection between the temp sensor and the choke magnet on a 1980 - - EXCEPT in the CANADIAN build, which (since this is all emissions stuff) is very different from the Fed/Cali builds.

 

I stand corrected. The old school 2, 3, 4, and Cosmo and later model FB are direct connected to the magnet. I didn't realize the 80 and maybe 79? was different.

 

Looks like in 79 the system was as you described, except for Cali-spec cars. They are more similar to the 80.

More evolution of the creeping smog requirements. Cali leading the way... to engineering hell!

 

Likely from disturbing the wires. I just swapped an aluminum water pump housing for the extra hole to run a fan switch. Now that temp sensor leaks and the wires broke off. I was quite careful as well. I'm going to bypass it for now, and remember to push the choke lever back in when up to temp driving.

Last I checked that switch wasn't cheap.