The Dodge Challenger Message Board

My Challenger did not come with an idle solenoid and I am having some trouble understanding how this thing is supposed to work. I have acquired a solenoid that works and it has the proper bracket to mount it to the intake. My problem is that I can't seem to find where the wire from the solenoid attaches to the engine harness. I would assume that the harness would have had a place (from the factory) for this hook-up. If anyone can help me understand--
1. Is this solenoid necessary?
2. What is its' actual function?
3. Where on the harness should I look for the connector?
4. Should the solenoid plunger activate with the key off or key on?

Any help would be greatly appreciated. I have been told that the solenoid is supposed to prevent the engine from "Dieseling" or "running on" after shut down. Thanks in advance.

Bill, The idea of the idle solenoid is to completly close the thottle blades on the centre carb as you turn off the engine effectivly choking it to prevent "running on". If you turn the ignition on the soleniod will open the carb back to your preset idle setting. My six pack didn't have one either but I can see that it would be a good idea to fit one. Sorry I can't help you with with your harness enquiery.

If the wiring harness is the correct 6-pack harness there will be a blue or purple (I can't remember exactly) wire that exits the loom around the distributor area and loops around the front of the intake. It has a connector on the end. Someone may have cut it off.

Mine has a butt connector from the harness that goes under the coil along the valve cover from the firewall. The wire is blue and comes out of the tape under the distributor cap.

Thanks Gentlemen. I will investigate the wiring routing and see what I can find as soon as I get off these long hours.

I saw mine at the weekend. Randy is indeed correct. The wire is blue. If you don't have the wire you can always just run one from the coil +ve terminal I guess.

Q: My Challenger did not come with an idle solenoid and I am having some trouble understanding how this thing is supposed to work.

A: It's simple. When the ignition is on then power is applied to the solenoid and extends it's plunger upwards. The fast curb idle speed adjustement screw on the arm on the curburator sits against the top of the plunger and you adjust the idle speed (900 RPM) with it. But when you turn off the ignition, the plunger retracts and the carburator closes even further to a position BELOW the normal idle speed position. This helps cut off the air and fuel flow into the engine and helps stop "run on" or dieseling.

1. Is this solenoid necessary?

No, not really. In IIRC this was only used on a few 1970 cars. It was required in California but not on the other 49 state cars. Starting in 1971 it was used on all cars.

2. What is its' actual function?

Above.

3. Where on the harness should I look for the connector?

The only schematic that I have that shows it is for a 340 4 bbl engine. On that one it's a dark blue wire and it comes from the I (field) terminal of the altenator.

4. Should the solenoid plunger activate with the key off or key on?

It extends (activates) with the ignition on. It retracts by spring pressure when the ignition is off.

NOTE: Some (all?) solenoids have two terminals, one at the top of the plunger and another at the bottom of the solenoid. Use the one at the bottom. The top one is is for an ignition timing retard system. This one shorts to ground via the carburator arm when the trottle is closed so make darn sure that you don't connect the blue wire there. Or you'll let the magic smoke out of your wiring harness!