Inspection Procedure 3

INSPECTION PROCEDURE 3: The ambient air temperature display does not change normally.

Ambient Air Temperature Sensor Circuit Part 1:

Ambient Air Temperature Sensor Circuit Part 2:

CIRCUIT OPERATION
The ambient air temperature display in the multi-center display unit is controlled by input signals from the ambient air temperature sensor and vehicle speed signals from the ECM or PCM .

TECHNICAL DESCRIPTION (COMMENT)
- If the vehicle speed does not exceed 20 km/h (12.4 mph) for 30 seconds or more, the rise in the ambient air temperature is not displayed.
- The ambient temperature sensor circuit is suspected to be open or short.

TROUBLESHOOTING HINTS
- Malfunction of the ambient air temperature sensor.
- Malfunction of the multi-center display unit
- Malfunction of the ECM or PCM
- Damaged wiring harness and connectors

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

- MB991223: Harness Set
- MB992006: Extra Fine Probe

STEP 1. Check the display of the multi-center display.

Q: Is error "-" displayed?

YES: Carry out INSPECTION PROCEDURE 2: "-" (AMBIENT AIR TEMPERATURE SENSOR ERROR) IS DISPLAYED ON THE AMBIENT TEMPERATURE DISPLAY.

NO: Go to Step 2..

STEP 2. Check while driving the vehicle.

Drive the vehicle at 20 km/h (12.4 mph) or more for 30 seconds or more to check that the ambient air temperature display changes.

Q: Did the ambient air temperature display change?

YES: There is no action to be taken.

NO: Go to Step 3.

STEP 3. Using scan tool MB991958, read the MFI system diagnostic trouble code.

Check if an MFI system diagnostic trouble code is set.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool.

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch "ON" position.
3. Read the MFI system diagnostic trouble code.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES: Diagnose the MFI system by referring to MFI Diagnosis - Diagnostic Trouble Code Chart <2.4L ENGINE> or MFI Diagnosis - Diagnostic Trouble Code Chart <3.8L ENGINE>.

NO: Go to Step 4.

STEP 4. Check multi-center display unit connector C-06 and ECM or PCM connector B-18 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are multi-center display unit connector C-06 and ECM or PCM connector B-18 in good condition?

YES: Go to Step 5.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the ambient air temperature display works normally.

STEP 5. Check the wiring harness between multi-center display unit connector C-06 (terminal 11) and ECM or PCM connector B-18 (terminal 14).

NOTE: Also check intermediate connectors C-28 and C-24 for loose, corroded, or damaged terminals, or terminals pushed back in the connectors. If intermediate connectors C-28 and C-24 are damaged, repair or replace the damaged component(s) as described in Harness Connector Inspection.

1. Disconnect multi-center display unit connector C-06 and ECM or PCM connector B-18, and measure the resistance at the wiring harness side.
2. Measure the resistance between multi-center display unit connector C-06 terminal 11 and ECM or PCM connector B-18 terminal 14.
- The resistance should be 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES: Replace the multi-center display unit.

NO: The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Verify that the combination meter works normally.