MANUAL A/C DIAGNOSIS
TSB Revision
HEATER, AIR CONDITIONING AND VENTILATION
55A-31
STEP 4. Check the wiring harness between ambient air
temperature sensor connector A-44 (terminals 2 and 1) and
ETACS-ECU connector C-312 (terminals 7 and 14).
• Check the sensor signal line and ground line for open and
short circuit.
Q: Is the wiring harness between ambient air temperature
sensor connector A-44 (terminals 2 and 1) and
ETACS-ECU connector C-312 (terminals 7 and 14) in
good condition?
YES : Go to Step 5.
NO : Repair the wiring harness.
STEP 5. Check the ambient air temperature sensor.
Measure the resistance between connector terminals 1 and 2
under at least two different temperatures. The resistance val-
ues should generally match those in the graph.
NOTE: The temperature at the check should not exceed the
range in the graph.
Q: Is the ambient air temperature sensor in good
condition?
YES : Replace the A/C-ECU. Then go to Step 6.
NO : Replace the ambient air temperature sensor. Then go
to Step 6.
STEP 6. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect scan tool MB991958 to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : The procedure is complete.
NO : Return to Step 1.
AC209192
10
8
6
4
2
0
AB
10
(50)
30
(86)
Resistance
(k
Ω)
Temperature ºC (ºF)
0
(32)
40
(104)
-10
(14)
20
(68)