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Question, induction worked fine. After removing Qjet for rebuild/restoration it simply stopped working. I see the switch, see pics, and I can push the plastic side stud up. Seems to move freely and spring back down.
That switch also activated the automatic transmission kickdown, if you have an auto that is correct for the car. If you flip the switch with the ignition on, you should hear the hood flap move. Mine is pretty loud and obvious. I had to replace the switch, since I noticed the transmission kickdown wasn't working. For me, it was the switch that was bad.
That switch also activated the automatic transmission kickdown, if you have an auto that is correct for the car. If you flip the switch with the ignition on, you should hear the hood flap move. Mine is pretty loud and obvious. I had to replace the switch, since I noticed the transmission kickdown wasn't working. For me, it was the switch that was bad.
mine is a 4 speed. I did put ignition on and pressed accelerator and no sound or move. Should I have 12 volts at the switch wire?
Doug
If you have a way to check for continuity when the switch is on, do that. If you have a good battery, you should have 12 volts on at least one side of the switch when the ignition is on. If you do not have one, I recommend getting a wiring diagram for your car so you can easily see which wires should be hot, etc.
If you have a way to check for continuity when the switch is on, do that. If you have a good battery, you should have 12 volts on at least one side of the switch when the ignition is on. If you do not have one, I recommend getting a wiring diagram for your car so you can easily see which wires should be hot, etc.
Hi again Doug,
Here is a little tip recommended by some to get your kick down ( as it's called ) switch to activate your Cowl induction Solenoid. I've tried it and it does work. Just cut a small piece if vacuum hose (what I used) and slip it on the switch in the location shown below in the photo. It allows the throttle rod to make contact to the switch sooner. These pics are from my '73. I believe my switch to be original. Your switch doesn't look exactly like mine but it just might be your camera angle, or it might be a newer switch. Better yet, it just might need to be reset!
However, I've also been told there is a way to reset the switch by using the directions in the GM Service manual, and the "trick" isn't needed! If you have one, try that first. I have one, but I won't be able to check it out until late tomorrow.
I'd suggest trying these tips first before purchasing another switch.
Jimmy
Switch with added piece of rubber! Original '73 Cowl induction Solenoid activation switch. Also serves as the THM400 'kickdown' switch.
The hood solenoid wiring harness was disabled on my SB 73 Manual car. After installing a new harness the solenoid would still not open at full throttle. I bought a new switch and still nothing. I finally used a test wire to jumper the switch and got the solenoid to work. Tried to “index” both switches but never got either one to close the circuit whenever the accelerator was pushed to full throttle. Finally read a post about adding a rubber doughnut on the round switch post, (it makes the switch hit the accelerator) and sure enough the solenoid opened when the car is floored. I used an extra rubber round doughnut that goes on the tire iron for the car jack. The problem was the switch was not being engaged by the accelerator pedal. It is very hard place to work, and it may be helpful to remove the seat unless you are tripled jointed. I can look for a picture if you need it.
Ok I'll try the above things, take a closer look at the switch to pedal.
Funny thing is it did work just fine before, then stopped working. I can push the switch side post
and it snaps up and springs back down, is that how the switch works?
Doug,
Since the air door stopped working after the carb was replaced, there is a possibility that a wire came loose/broken between it and the firewall. Check the connections starting at the solenoid in the hood. Also Check the plug/socket by the headlight actuator (picture attached) as it may have come loose. Follow the wiring the entire length to look for anything that was disturbed.
Doug,
Since the air door stopped working after the carb was replaced, there is a possibility that a wire came loose/broken between it and the firewall. Check the connections starting at the solenoid in the hood. Also Check the plug/socket by the headlight actuator (picture attached) as it may have come loose. Follow the wiring the entire length to look for anything that was disturbed.
Fran
wire connected. Per assembly manual to set switch I pushed switch stud up, seated in place. Manual says next WOT will reset switch. I pressed accelerator with my hand and pedal rod did contact switch stud and move switch arm. So, will take a ride later and see it it works.
You can hear if it works without taking it for a ride. Turn the ignition to ON, do not start engine. Press the accelerator pedal to the floor; If it works, you will hear the flap door open. Release accelerator pedal and you will hear it close. Sounds like a "thump thump".
You can hear if it works without taking it for a ride. Turn the ignition to ON, do not start engine. Press the accelerator pedal to the floor; If it works, you will hear the flap door open. Release accelerator pedal and you will hear it close. Sounds like a "thump thump".
Fran
Well not working. After my ride and no sense it's working I had my wife watch the flapper with a flashlight. Ignition on pedal down and nothing. I then pulled the switch down by hand in case pedal rod was not moving it enough, and nothing.
So it would have to be the switch or the solenoid on the hood flapper gone bad?
Pulled wire from accelerator pedal switch, with key on I have 12 volts at the wire. And hooked up and key on, press accelerator and no flapper function. So next step:
Can I safely pull tan wire near headlight actuator and run a lead wire from alternator battery stud to the tan wire, and should hood solenoid click door open? If it opens then my accelerator switch is bad. If it does not open then the solenoid is bad?
Doug,
Note that 2 wires go from the plug near the headlight actuator to the flapper solenoid. Tan is positive and the dark one (black or dark blue in my picture) is the ground. Both have to have "juice" to make it work, especially the ground. Check the metal tangs of the plug and socket; they may need cleaning.
PS: get a good ground and 12V + source and hold to terminals of solenoid to check if it is good.
Fran
Last edited by Blue73Shark; Apr 24, 2022 at 12:43 PM.
Reason: Add more ideas.
Doug,
Note that 2 wires go from the plug near the headlight actuator to the flapper solenoid. Tan is positive and the dark one (black or dark blue in my picture) is the ground. Both have to have "juice" to make it work, especially the ground. Check the metal tangs of the plug and socket; they may need cleaning.
PS: get a good ground and 12V + source and hold to terminals of solenoid to check if it is good.
Fran
Ok, so best is to remove hood panel, remove wire from solenoid, then just apply 12V from alternator stud to the solenoid itself plus ground the solenoid also?
Ok, so best is to remove hood panel, remove wire from solenoid, then just apply 12V from alternator stud to the solenoid itself plus ground the solenoid also?
Tks. Doug
Yes. It might be a little stiff from non use. Give it a nudge or light tap to free up. Lubricate shaft if needed after seeing that it works.
Doug,
Note that 2 wires go from the plug near the headlight actuator to the flapper solenoid. Tan is positive and the dark one (black or dark blue in my picture) is the ground. Both have to have "juice" to make it work, especially the ground. Check the metal tangs of the plug and socket; they may need cleaning.
PS: get a good ground and 12V + source and hold to terminals of solenoid to check if it is good.
Fran
Ok, tested and tell me if i'm right.
12 volts showing at wire to accelerator switch, and key on WOT there is no hood flapper movement.
Took solenoid out of hood, ran battery wire to it with ground and although it looks grungy it does pop arm out and in. Smooth as silk.
So, see pic, I hooked my volt meter to hood wire lead and ground wire, ignition on and pressed accelerator and I get no volt reading. So, does this verify the accelerator switch is bad, 12 volts not getting to hood wire?
This is a NCRS recent restoration so the wires and wire at headlight actuator are in excellent shape.
Doug,
Good to know solenoid works. Your test does not indicate your switch is bad; it may be the wires between it and the solenoid. I suggest checking the wires and connecteors first (bypassing the switch) as they may look OK but have failed somehwe along the way. Hook up a 12V source (+ and - or ground) to the two wires that connect to the solenoid.
Go to the connector by the headlamp actuator and see if it shows 12V; check both sides (solenoid side "other" side). If you have 12V there, measure at the switch, which I think would be the next connection point withou tearing into the harness. If 12V is there, then it most likely is the switch. If not there is a break in the wire harness. Also check where the black wire connects to ground; it may look OK but be corroded.
Use both test probes from the meter to make each test.
Doug,
Good to know solenoid works. Your test does not indicate your switch is bad; it may be the wires between it and the solenoid. I suggest checking the wires and connecteors first (bypassing the switch) as they may look OK but have failed somehwe along the way. Hook up a 12V source (+ and - or ground) to the two wires that connect to the solenoid.
Go to the connector by the headlamp actuator and see if it shows 12V; check both sides (solenoid side "other" side). If you have 12V there, measure at the switch, which I think would be the next connection point withou tearing into the harness. If 12V is there, then it most likely is the switch. If not there is a break in the wire harness. Also check where the black wire connects to ground; it may look OK but be corroded.
Use both test probes from the meter to make each test.
Fran
Ok, I already have 12 volts at the wire connector which plugs into the accelerator switch. I can also just do a continuity test from the accelerator wire to the headlight actuator location, then the other side of that connector up to the wire ending at the hood.
If that all shows full continuity then I can assume the accelerator switch is bad.
Do you think I should use the 50 year old solenoid or get a new one (China made?).
73 hood induction stopped working
If you have one, try that first. I have one, but I won't be able to check it out until late tomorrow.
