Chart C-1A - Park/Neutral Switch Relay

Park/Neutral switch contacts are closed to ground in Park or Neutral and open in all other ranges. ECM supplies voltage through a resistor on Pink/Blue wire from ECM to relay. ECM senses when switch is closed and voltage decreases to less than one volt on Pink/Blue wire. ECM uses this input to control idle speed, EGR operation and vehicle speed sensor diagnostics.

If Pink/Blue wire indicates Park or Neutral (grounded) while in Drive range, EGR will not operate, resulting in possible detonation. If Pink/Blue wire indicates Drive (open), a decrease in idle speed may occur when gearshift is placed in gear.

1. This step checks for a closed switch to ground in Park position.
2. This step checks for an open switch in Drive range.
3. Ensure Scan tester indicates Drive even while slightly moving gearshift. This will check for an intermittent or misadjusted switch in Drive or Overdrive range.

Fig 1: Chart C-1A Schematic - Park/Neutral Switch Relay

Courtesy of ISUZU MOTOR CO.

Fig 2: Chart C-1A Flow Chart - Park/Neutral Switch Relay

Courtesy of ISUZU MOTOR CO.