I had never heard of the Anti-Diesel Solenoid, until I looked at the drawings you posted. Where is it located?
Apparently it is mounted on the LH side of the carburetor and is designed to kick up the idle speed - but only when the truck has HD emissions and a 4 manual transmission
Campaign - Carburetor Anti-Dieseling Solenoid Connection
NUMBER: 86-E-11
Group: 6E-Emission Controls
DATE: June, 1987
SUBJECT:
CARBURETOR ANTI-DIESELING SOLENOID CONNECTION
MODELS: 1985-1986 C/K 25 LIGHT DUTY MODEL TRUCKS EQUIPPED WITH 5.7L GAS ENGINES (LT9), HEAVY DUTY FEDERAL EMISSIONS (H5D/NAS), AND 4 SPEED MANUAL TRANSMISSION (M20)
General Motors has determined that the engine electrical harness pigtail was not connected to the
anti-dieseling solenoid on the
carburetor of Flint production 1985-1986 light duty C/K 25 models equipped with 5.7L gas engines and manual transmissions and heavy duty Federal emissions. Not connecting the engine harness to this solenoid results in a curb
idle speed of 600 rpm rather than the specified 800 rpm curb idle. It is necessary to connect the existing engine electrical harness pigtail to the anti-dieseling solenoid to bring these vehicles into conformity.
VEHICLES INVOLVED Involved are all 1985-1986 light duty model C/K 25 trucks equipped with 5.7L gas engines (RPO LT9) with heavy duty Federal emissions (H5D/ NA5) and 4-speed manual transmissions (M20) within the following vehicle identification and manufacture date parameters:
Flint Plant 1985 From Through 1986
Line #1 FF710952 GF724660
1/1/85 4/24/86
Line #2 FF514844 GF523016
1/1/85 4/24/86
The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin.
DEALER CAMPAIGN RESPONSIBILITY Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of mileage, age of vehicle, or ownership, from this time forward.
Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service in the future, you should take the steps necessary to ensure the campaign correction has been made before reselling or releasing the vehicle. Owners of vehicles recently sold from your new vehicle inventory are to be contacted by the dealer and arrangements made to make the required correction according to instructions contained in this bulletin. If no owner's name and address were available to GMC Truck Division at the time of campaign initiation, the dealer will determine the owner's name and address from the dealership sales records. Please provide this information directly on the second copy of the listing next to the applicable VIN so that our records may be updated and the appropriate notification mailed to the owner. This second copy should then be submitted to the address listed below in the previously supplied yellow campaign envelopes.
GMC Truck Division General Motors Corporation 101 Union Street Plymouth, Michigan 48170
OWNER NOTIFICATION Owners will be notified of this campaign on their vehicles by GMC Truck Division (see copy of the Owner Letter included with this bulletin). A listing of owner names and addresses has been furnished to the involved dealers to enable dealers to follow up with owners involved in this campaign. This listing may contain owner names and addresses obtained from state motor vehicle registration records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to this campaign.
You must be registered for see images attach
SERVICE PROCEDURE Refer to Figure No. 1
1. Remove the air cleaner assembly.
2. Locate the carburetor solenoid.
3. Inspection:
^ If there is a single wire pigtail which is pink with a black stripe connected to the
anti-dieseling solenoid no further action is required. Proceed to step 4.
^ If there is nothing connected to the antidieseling solenoid locate the pink with a black stripe pigtail which is part of the engine harness and connect it to the antidieseling solenoid. Proceed to step 4.
^ If there is a dark green electrical pigtail connected to the
anti-dieseling solenoid unplug it and tape it back out of the way. Locate the pink with a black stripe pigtail which is part of the engine harness and connect it to the solenoid.
4. Reinstall air cleaner assembly.
You must be registered for see images attach
Here is a better view - in this dwg it's called a carburetor air fuel solenoid:
You must be registered for see images attach
And that's all I know about this component - I certainly wouldn't stress about it. They forgot to even hook the stupid thing up at the Flint plant for two years. If you read between the lines of the "Campaign Notice" (that's the worst kind of TSB) - some people got their asses kicked - and probably fired.
