Code 23 - M/C Solenoid Circuit Low

Code 23 indicates that ECM has sensed a low steady voltage at ECM terminal No. 18. Normal voltage at terminal No. 18 is rising and falling as solenoid is turned on and off. This could be caused by a ground on the ECM side of solenoid or an open in the M/C solenoid circuit. A grounded circuit will cause a full lean condition and poor driveability. An open circuit will cause a full rich condition, along with poor economy, odor, smokey exhaust or poor driveability.

1. 1) This test checks for a complete circuit from battery to M/C solenoid dwell lead. Normal reading should be battery voltage. Battery voltage means there might be an open circuit No. 411 between dwell connector and ground. No voltage could be caused by either an open between connector and ignition source or a ground on ECM side of M/C solenoid.
2. 2) This test checks for battery voltage on circuit No. 439 to ignition source. Test light should illuminate between ignition source and ground.
3. 2A) This test checks for an open circuit No. 411 in solenoid to ECM circuit. Normal circuit will read about battery voltage at ECM terminal No. 18.
4. 3) This test determines whether fault is in M/C solenoid, a ground in ECM circuit No. 411, or ECM. A light will indicate a ground in circuit No. 411 to terminal No. 18 or a faulty ECM. A test light must be used in this step. A voltmeter may give an inaccurate indication.
5. 4) This test checks for ground in circuit No. 411 to ECM terminal No. 18. If circuit is grounded, light will stay on.

Fig 1: Code 23, M/C Solenoid Circuit Low Flow Chart

Fig 2: Code 23, M/C Solenoid Circuit Low Flow Chart