DTC 23

Fig. 036 - Wiring Diagram for Code 23 M/C Solenoid Circuit Low. VIN C:

CODE 23, M/C SOLENOID CIRCUIT LOW

Trouble Code 23 says the ECM has seen the low voltage at ECM terminal "14" stay low instead of rising and falling as the M/C solenoid is turned "ON" and "OFF". This could be caused by an open in the M/C solenoid circuit or a ground on the ECM side of the M/C solenoid.
An open would cause a full rich condition and cause poor fuel economy, odor, smokey exhaust or poor driveability. A ground would cause a full lean condition and cause poor driveability.

Fig. 035 - Chart - Code 23 M/C Solenoid Circuit (Open Or Grounded.:

1. Checks for a complete circuit from the battery to the M/C solenoid dwell lead. It should be battery voltage. Battery voltage means there might be an open circuit between the dwell connector and ground. No voltage could be either an open between the connector and battery or a ground on the ECM side of the M/C solenoid.
2. Checks for voltage on the pink/black ignition source wire. Test light should light between the ignition source to ground.
2a. Checks for an open in the solenoid to ECM circuit. A normal circuit would read about battery voltage at the ECM Terminal "14".
3. This step determines whether the fault is in the M/C solenoid or a ground in the circuit to the ECM or the ECM. A light would indicate a ground in circuit to Terminal "14" or a faulty ECM. A voltmeter can't be used because it is normal to have enough current flow through the ECM to make a voltmeter read, but not enough to light a test light.
3a. This step determines if the M/C solenoid is shorted. A good solenoid will have over 10 ohms resistance. A shorted solenoid could cause the ECM to fail.
4. This checks for ground in the wire to ECM Term. "14". If it is grounded, the light will stay "ON".