Topic: 70 428CJ w/AC - Throttle solenoid wiring question

[wjgrnp]

HI
I have recently restored my carburettor and replaced the air conditioning throttle solenoid with a NOS model.
I am unsure where the solenoid plugs into the wiring harness.I have also purchased the extension wire.
I have read in the service manual that the solenoid should come on once the air conditioner is operating and assume I am looking for a female connector.
Any direction would be greatly appreciated.
Thanks
Ward

[J_Speegle]

Guessing this is for your 70 428CJ. Often it helps to confirm since it seems many here have multiple cars, years, plants , engines ........

Well you might be able to find it by turning on the AC and testing the gang of female plugs that should be sticking through the firewall about in the center.

You'll need one hot for your AC compressor.  Haven't looked at the wiring diagram to confirm if the solenoid hooks to the same (with a Y somewhere in the system) plug in some way or another plug

A fair number of 70's have solenoid but they often are installed for a number of reasons and not all are triggered by the AC so showing that other routing might mislead you so I need to look for something more similar to what you have.

[midlife]

The wire you're looking for just past the firewall grommet is a greyish blue wire with a white large female bullet (1970 only).  The extension plugs into that and to your carb solenoid.

[specialed]

and is used only on 70 428 cj with A/C  both auto & 4-speed

[J_Speegle]

Great help guys

Different engine  - same principle. From a post I was preparing. Don't know if the same solenoid and mount was used on the 70CJ. This is a 70 Autolite 4300.

[wjgrnp]

Thanks for the advice however I am still having problems.
I have identified a black female connector where the loom comes out through the firewall.
It has 2 wires coming from it. One black and another that appears to be olive with orange.
Have turned on the air and put the test light on it however there appears to be no power.
I have identified that fuse 4 is either spare or required for emission control and/or throttle solenoid. Replaced the fuse but still no power.
Is this the correct connector?
Thanks

[midlife]

The black female with two wires is unique for 1970, and that is the PRNDL lamp wire for a Mach 1 with sportslamps.  No, you need to look for a white molded female bullet for the carb solenoid.

[wjgrnp]

Hi Midlife
The only other female bullet I can locate at the firewall is white however it is in use.
I have not traced it yet however it heads to the rear of the car along the top of the bell housing.
Are there 2 white bullets?
Thanks for your continued help.

[midlife]

No, there are not two white bullets.  I suspect that it is currently used for the PRNDL shifter lamp.  If true, the shfiter lamp will only light up with the key in RUN position.  It is supposed to light in the ACC and RUN positions.  Another key to look for is whether the mating male bullet matches the white molding and whether the mating wire is of the same color as from the main harness side (female bullet's wire colors).  The two wire affair will have a brown wire and a blue/red wire. 

[wjgrnp]

You are correct in your assumption that the shift lamp is connected to the white female.
I have now connected the shift lamp to the two wire bullet. Shift lamp now only comes on with the key in run and the lights on. Is this correct?
I have also connected the solenoid to the white female. However the solenoid is engaged as soon as the key is turned to run. Having the air conditioning off does not disengage the solenoid.
Thanks for your continued help

[midlife]

Both conditions as you describe are correct, at least electrically.  I have no clue as to how the carb solenoid works or under what conditions, other than power is only supplied when the key is in RUN.

I overlooked the fact that the PRNDL shifter lamp is controlled by the headlight switch, so it has to be pulled out to the first or second detent.  Actually, the shifter light will work without the key engaged.

[67gtasanjose]

Both conditions as you describe are correct, at least electrically.  I have no clue as to how the carb solenoid works or under what conditions, other than power is only supplied when the key is in RUN.

+1, I have no idea how the solenoid is intended to operate ON THIS APPLICATION, but I can add this to the discussion. FIRST, a FORD produced Service Manual would be the best source of how the circuit was intended to function, a detailed wiring diagram would easiest answer every question, which I do not have for this year vehicle to reference. .

This above being said to next describe how I think the circuit was intended, based on the discussion so far.

In an effort to prevent "Dieseling", this solenoid is often added to drop the idle speed, effectively cutting off the fuel which prevents the dieseling (afterrun) of the engine. IT DOES NOT ALWAYS HAVE TO BE AN IDLE SPEED COMPENSATOR FOR AIR CONDITIONING as the O.P. seems to be describing. There are occasions, that people will call it such. AGAIN, refer to original wiring diagrams and if possible, assembly manuals for an exact account of the purpose this solenoid was designed to do and the correct method of making any connections. It seems Randy has helped sort some of the misconnections already but without a vehicle-specific wiring diagram, it would be difficult for any bystander to assist further...at least without pictures, such as Jeff is known for. Also, most of the time, the connections at the firewall are sprayed with a sealant at time of assembly, rendering a photograph only "some help" at best. Maybe somebody has a photograph of your exact optioned vehicle, but these years (1970) are ALL OVER THE PLACE when it comes to "exact list of options", making it rather daunting to be "correct" for your specific needs.

[J_Speegle]

In an effort to prevent "Dieseling", this solenoid is often added to drop the idle speed, effectively cutting off the fuel which prevents the dieseling (afterrun) of the engine. ............

Not a big thing but believe the solenoid cuts off the air part of the triangle - allowing the throttle plates to close enough to chock the engine - below the idle point

At least that was my understanding from reading the descriptions

[WT8095]

Found a couple of interesting blurbs in the September, 1969 issue of Shop Tips (Vol. 8 Issue 1).

The entire issue can be found in PDF form here:
http://www.mustangtek.com/Library6/PDF/ShopTips8-1.pdf

I would imagine the shop manual would have more detailed info.

[67gtasanjose]

Not a big thing but believe the solenoid cuts off the air part of the triangle - allowing the throttle plates to close enough to chock the engine - below the idle point

At least that was my understanding from reading the descriptions

CORRECT! The carburetor cannot draw fuel into the manifold without the passing "air" though the venturies, so yes,...we're on the same page, your explaination helps to add further depth to the principle causes of dieseling.. (and helps those learning )

NO FUEL, no DIESLEING,... NO AIR, Fuel cannot detonate (from heat & compression)  the two causes of the trifecta are simultaniously terminated which = Engine Shuts off.
Early diesel engines used to use the "Air-Choke" method to shut them off (e.g. Detroit Diesels). Today's gasoline & diesel engines generally use fuel solenoids to shut them down. (better idea) "Diesel ignition" (dieseling) is caused from the friction between air/fuel molecules under extreme compression. The friction itself creates the ignition of a good air/fuel mixture ~no spark needed. Every fireman knows this Many older gasoline engines had very high compression causing this "dieseling" when the ignition switch is turned off. Solenoids were developed to assist in terminating this condition.