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Home >> Geo >> 1991 >> Storm Base, 2D Hatchback, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Engine Sensors & Switches >> Park/Neutral Switch
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Park/Neutral Switch

  1. Park/neutral switch contacts are closed in Park or Neutral and open in all other gears. Park/neutral switch provides current to neutral relay when in Park or Neutral. Neutral relay contacts close, causing signal voltage on Pink/Blue wire from ECM to decrease.
  2. ECM monitors signal voltage and determines vehicle is in Park or Neutral when signal voltage decreases to less than one volt.
  3. To check switch and circuit operation, turn ignition on with engine off. Install Scan tester. Scan tester should display "P/N" with transaxle in Park or Neutral and "R-D-L" in all other gears.
  4. If Scan tester displayed correctly, park/neutral switch and wiring circuit are okay. If Scan tester does not display correctly, disconnect electrical connector from neutral relay. Neutral relay is located in relay box in right corner of engine compartment, near strut tower.
  5. With transaxle in Park or Neutral, Scan tester should display "P/N". If "P/N" is displayed, proceed to step 6). If "P/N" is not displayed, Pink/Blue wire between neutral relay and ECM is grounded or ECM is defective. The ECM is located under left side of instrument panel, left of steering column.
    CAUTION: Automatic transaxle Electronic Control Unit (ECU) on 4-speed transaxle may be mounted on left side of steering column. DO NOT confuse this with the ECM. The ECM contains 24-pin and 32-pin connectors, and the ECU contains 16-pin and 20-pin connectors.
  6. Using fused jumper wire, ground Pink/Blue wire terminal at neutral relay electrical connector. Scan tester should now display "R-D-L". If "R-D-L" is displayed, proceed to step 7). If "R-D-L" is not displayed, check for open circuit in Pink/Blue wire between neutral relay and ECM or for defective ECM connector. If wiring and ECM connector is okay, ECM is defective.
  7. Connect test light between White/Blue wire terminal on neutral relay electrical connector and ground. Test light should come on when transaxle is in Drive or Reverse.
  8. If test light comes on in Drive or Reverse, proceed to step 12). If test light does not come on, proceed to step 9).
  9. Using test light, probe Red/Black wire at park/neutral switch, located on top of transaxle, near the battery. Test light should come on. If test light comes on, proceed to step 11).
  10. If test light does not come on, check for open circuit in Red/Black wire between park/neutral switch and fuse C-11 (15-amp fuse for Storm) or C-12 (10-amp fuse for Storm GSi), located in junction block behind left kickpanel.
  11. If test light comes on, check park/neutral switch adjustment or for open circuit in White/Blue wire between neutral relay and park/neutral switch. If wiring and switch adjustment are okay, park/neutral switch is defective.
  12. It test light comes on with park/neutral switch in Drive or Reverse, check for defective electrical connection at neutral relay. If electrical connection is okay, check for open circuit in Black ground wire to neutral relay. If wiring is okay, neutral relay is defective.
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