Code 23: Mixture Control (M/C) Solenoid CKT Low

Code 23 indicates that the ECM has sensed a low steady voltage at ECM term. "18". Normal voltage at term. "18" is rising and falling as the solenoid is turned "ON" and "OFF". This code could be caused by a ground on the ECM side of the M/C solenoid or an open in the M/C solenoid circuit. A grounded circuit will cause a full lean condition and very poor driveability. An open circuit will cause a full rich condition and poor economy, odor, smoky exhaust or poor driveability.

1. 1)  This test checks for a complete circuit from the battery to the M/C solenoid dwell lead. Normal reading should be battery voltage. Battery voltage means there might be an open circuit between 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. 2)  This test checks for battery voltage on the pink ignition source wire. Test light should light between the ignition source and ground.
3. 2A)  This test checks for an open in the solenoid to ECM circuit. Normal circuit will read about battery voltage at Term. "18" of the ECM.
4. 3)  This test determines whether fault is in the M/C solenoid, a ground in the circuit to the ECM or the ECM. A light will indicate a ground in circuit to term. "18" or a faulty ECM.
5. 4)  This checks for ground in wire to ECM terminal 18. If it is grounded, light will stay ON.