Mercury F5AZ-7A247-A Switch Assembly - Starter Inhibitor

To check the operation of the neutral safety switch, apply the parking brake and try to start the engine in each position of the selector lever. The engine should start only in Park and Neutral. If it starts in any other position, adjust the shift linkage and retest. If the engine still starts in any position other than Park or Neutral, replace the switch. To replace the switch, disconnect the cable from the negative battery terminal, place the shift lever in Low and apply the parking brake. Raise the vehicle and place it securely on jackstands. Unplug the electrical connector from the neutral safety switch. Carefully unscrew the switch and O-ring. Install the switch and new O-ring, tightening it to the specified torque. Be cautious not to crush or puncture the walls of the switch. Install the electrical connector and connect the negative battery cable. Verify that the engine starts only when the selector is in the Neutral and Park positions. The AODE transmission used on 1992 through 1994 models does not have a neutral safety switch. That function has been incorporated into an information sensor known as the Manual Lever Position (MLP) sensor. And 1995 and later models, which are equipped with a 4R70W transmission, use a transmission range (TR) sensor, a similar device.

The MLPS adjusting tool should be used to adjust the MLPS.

The engine should start only with the transmission lever in Park and Neutral.

For more information on the MLP or TR sensor, refer to Section 4 in Chapter 6. For adjustment, see Section 7 of this Chapter.

Yes, the EEC system can detect sensor problems and set trouble codes to indicate specific faults.

You should check for signal voltage (10 volts or more). Replacement involves disconnecting the electrical connector, removing the retaining bolt, and lifting the VSS from the transmission.

The TR sensor serves as an information sensor for the powertrain control module (PCM) and performs functions similar to a Park/Neutral switch. It prevents the engine from starting in any gear other than Park or Neutral and activates the back-up lights when the shift lever is in Reverse. It also includes the sensing circuit for Neutral in 4X4 Low range on 4WD models.

To check the operation of the neutral start switch, apply the parking brake and try to start the engine in each position of the selector lever. The engine should start only in Park and Neutral. If it starts in any other position, adjust the shift linkage and retest. If the engine still starts in any position other than Park or Neutral, replace the switch.