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DTC 27: Park/Neutral Position Switch System (Open Circuit)

CIRCUIT OPERATION
^ Battery positive voltage is applied to the Park/Neutral position switch (terminal 8) when the ignition switch is turned "ON."
^ Battery positive voltage is applied to the PCM (terminal 101) when the selector lever is in the "P" range. The PCM judges that the selector lever is in the "P" range when the battery positive voltage is applied.
^ Battery positive voltage is applied to the PCM terminal 108 (121, 102, 109, 122 or 110) when the selector lever is in the "R" range ("N." "D," "3," "2" or "L" range). The PCM judges that the selector lever is in the "R" range ("N." "D," "3," "2" or "L" range) when the battery positive voltage is applied.

DTC SET CONDITIONS
If the PCM detects no Park/Neutral position switch input signal from any selector position for a continuous period of thirty seconds or more, it is judged that there is an open circuit in the Park/Neutral position switch and DTC 27 is set.

TROUBLESHOOTING HINTS
(The most likely causes for this code to be set are:)
^ Malfunction of the Park/Neutral position switch
^ Malfunction of the ignition switch
^ Damaged harness or connector
^ Malfunction of the PCM

DIAGNOSIS

Required Special Tool:
^ MB991502: Scan Tool (MUT-II)

STEP 1.Using scan tool MB991502, check data list item 61: Park/Neutral Position Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Set scan tool MB991502 to data reading mode for item 61, Park/Neutral Position Switch.
^ Move the selector lever to "P," "R," "N," "D," "3," "2," "L" positions and confirm that the selected selector lever positions match the positions shown on scan tool M B991502.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the switch operating properly?
YES: It can be assumed that this malfunction is intermittent.
NO: When the selector lever position does not match any of the positions shown on scan tool MB991502: Go to Step 2. When the selector lever position does not match the "P" position on scan tool MB991502: Go to Step 6. When the selector lever position does not match the "R" position on scan tool MB991502: Go to Step 12. When the selector lever position does not match the "N" position on scan tool MB991502: Go to Step 17. When the selector lever position does not match the "D" position on scan tool MB991502: Go to Step 22. When the selector lever position does not match the "3" position on scan tool MB991502: Go to Step 27. When the selector lever position does not match the "2" position on scan tool MB991502: Go to Step 32. When the selector lever position does not match the "L" position on scan tool MB991502: Go to Step 37.

STEP 2. Check the Park/Neutral position switch.

Measure the resistance between the terminals for each selector position as indicated in the table above.
Q: Does the resistance measure less than 2 ohms for each selector position?
YES: Go to Step 3.
NO: Replace the Park/Neutral position switch.

STEP 3. Check Park/Neutral position switch connector B-16, intermediate connector C-123 and junction block connector C-210 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition?
YES: Go to Step 4.
NO: Repair or replace the damaged components.

STEP 4. Check harness for open or short circuit to ground between Park/Neutral position switch connector B-16 terminal 8 and junction block connector C-210 terminal 12.

Q: Is the harness wire in good condition?
YES: Go to Step 5.
NO: Repair or replace the harness wire.

STEP 5. Using scan tool MB991502, check data list item 61: Park/Neutral Position Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

Q: Does the resistance measure less than 2 ohms for each selector position?
YES: Go to Step 7.
NO: Replace the Park/Neutral position switch.

STEP 7. Check Park/Neutral position switch connector B16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition?
YES: Go to Step 8.
NO: Repair or replace the damaged components.

STEP 8. Measure the Park/Neutral position switch output voltage at PCM connector C-114 by backprobing.

1. Do not disconnect connector C-114.
2. Turn the ignition switch to the "ON" position.
3. Move the selector lever to the "P" position.

4. Measure the voltage between terminal 101 and ground by backprobing.
^ The voltage should measure battery positive voltage.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the voltage measure battery positive voltage?
YES: Go to Step 11.
NO: Go to Step 9.

STEP 9. Check PCM connector C-114 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition?
YES: Go to Step 10.
NO: Repair or replace the damaged components.

STEP 10. Check harness for open circuit or short circuit to ground between Park/Neutral position switch connector B16 terminal 3 and PCM connector C-114 terminal 101.

Q: Is the harness wire in good condition?
YES: Go to Step 5.
NO: Repair or replace the harness wire.

STEP 11. Check PCM connector C-114 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition?
YES: Go to Step 5.
NO: Repair or replace the damaged components.

STEP 12. Check the Park/Neutral position switch. Measure the resistance between the terminals for each selector position as indicated in the table above.

Q: Is the measured resistance less than 2 ohms for each selector position?
YES: Go to Step 13.
NO: Replace the Park/Neutral position switch.

STEP 13. Check Park/Neutral position switch connector B16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition?
YES: Go to Step 14.
NO: Repair or replace the damaged components.

STEP 14. Measure the Park/Neutral position switch output voltage at PCM connector C-114 by backprobing.

1. Do not disconnect connector C-114.
2. Turn the ignition switch to the "ON" position.
3. Move the selector lever to the "R" position.

4. Measure the voltage between terminal 108 and ground by backprobing.
^ The voltage should measure battery positive voltage.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the voltage measure battery positive voltage?
YES: Go to Step 11.
NO: Go to Step 15.