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Home >> Mercedes Benz >> 2012 >> CL 600 (216.376) V12-5.5L Turbo (275.953) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Manufacturer Code Charts >> 202A

202A


Ambient temperature values are implausible. (P0071, P0072)


Possible cause:

- B14 (Ambient temperature display temperature sensor)
Affected functions:

- Engine diagnosis

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Test 1: Ambient temperature values are implausible.

1. Ambient temperature values are implausible.
Preconditions for test Ambient temperature
Test prerequisite

- Air filter and associated hoses are correctly fitted.
Test sequence

- Drive vehicle with constant engine load at a speed of > 50 km/h (> 31 mph) for approx. 5 min.
Status of the relevant actual values:
- B14 (Ambient temperature display temperature sensor):Warning! Communication with ECU required.

- B17/8 (Charge air temperature sensor):Warning! Communication with ECU required.
Question

- Is the temperature difference between component B14 (Ambient temperature display temperature sensor) and component B17 (Intake air temperature sensor) greater than 40° C?


YES

Test 1.1: Check component B17 (Intake air temperature sensor).

Test 1.2: Check component B14 (Ambient temperature display temperature sensor).

1.1. Check component B17 (Intake air temperature sensor).

Test 1.1.1: Check component B17/8 (Charge air temperature sensor) using actual value.

Test 1.1.2: Check low-temperature circuit.

Test 1.1.3: Check internal resistance of component B17/8 (Charge air temperature sensor).

1.1.1. Check component B17/8 (Charge air temperature sensor) using actual value.
Test sequence

- Switch on ignition.
Status of relevant actual value:
- B17/8 (Charge air temperature sensor):Warning! Communication with ECU required.
Specified value

- If the connection is unplugged at component B17/8 (Charge air temperature sensor), the value is approx. -40° C.
- Bridge pin 1 in pin 2 at the unplugged connection of component B17/8 (Charge air temperature sensor).Value may be within the range from 140° C to 170° C.
Question

- Is the actual value o.k.?







YES
The actual value is okay.Further possible causes of fault

- Air in low-temperature circuit
- Check low-temperature circuit.


NO
The actual value is not o.k.Possible cause and remedy

- Check lines from component B17/8 (Charge air temperature sensor) to component N3/10 (ME-SFI [ME] control unit).
End of test

1.1.2. Check low-temperature circuit.
Information

- The low temperature coolant circuit cap may only be opened when the low temperature circuit is cold (ambient temperature).To cool the low temperature circuit quickly, detach component N10/2kQ (Circulation pump relay) and link circuits 30 and 87.At the same time, actuate the electric suction fan via DAS.
Continue to test with button F2













Note

- WIS is not available on this system.
- It is not possible to display the requested WIS document [ ar2000p1145h ].
- You can start WIS on another system and display the WIS document by entering the document number [ ar2000p1145h ] in the 'Contents' field.


1.1.2. No further information available.

1.1.3. Check internal resistance of component B17/8 (Charge air temperature sensor).
Test prerequisite

- The actual value is not o.k.
Test sequence

- Switch off ignition.
- Measure resistance with multimeter between pins (B17/8) 1 and (B17/8) 2
Specified values

- Resistor(20° C): [5763...6370]ohms
- Resistor(30° C): [3792...4191]ohms
- Resistor(40° C): [2473...2733]ohms
- Resistor(50° C): [1679...1856]ohms
- Resistor(60° C): [1165...1288]ohms
- Resistor(70° C): [822...909]ohms
- Resistor(80° C): [591...654]ohms
- Resistor(100° C): [321...355]ohms
Question

- Are the measurement values OK?







YES
The measurement values are OK.End of test

NO
The measurement values are not OK.Possible cause and remedy

- B17/8 (Charge air temperature sensor)
End of test

1.2. Check component B14 (Ambient temperature display temperature sensor).
Test prerequisites

- The power supply of component N10/1 (Front SAM control unit with fuse and relay module) is OK.
- Fault code 9103 is current, and (or) at least one of the relevant actual values is not OK.
Status of relevant actual value:
- B14 (Ambient temperature display temperature sensor):Warning! Communication with ECU required.
Test sequence

- Detach coupling at component B14 (Ambient temperature display temperature sensor).
- Connect resistance simulator to the connector of component B14 (Ambient temperature display temperature sensor).
- Connect resistance substitution unit between sockets (B14)1 and (B14) 2
- Adjust resistance values one after another and compare them with the actual value.
Specified value

- Resistor9.6 kohms :Temperature: [0° C]
- Resistor5.9 kohms :Temperature: [10° C]
- Resistor3.7 kohms :Temperature: [20° C]
- Resistor2.4 kohms :Temperature: [30° C]
- Resistor1.6 kohms :Temperature: [40° C]
Question:Is the actual value o.k.?







YES
The actual value is okay.Possible cause and remedy

- Component B14 (Ambient temperature display temperature sensor) is defective.
End of test







NO
The actual value is not o.k.Possible cause and remedy

- Test cable from control module N10/1 (Front SAM control unit with fuse and relay module) (connector MR7, pin 26) to component B14 (Ambient temperature display temperature sensor) (connector 1, pin 1).
- Test cable from control module N10/1 (Front SAM control unit with fuse and relay module) (connector MR7, pin 18) to component B14 (Ambient temperature display temperature sensor) (connector 1, pin 2).
- Inspect cables, connectors, plug connections, fuses and electrical components for signs of damage, correct connection, loose contact, corrosion etc.
- Component N10/1 (Front SAM control unit with fuse and relay module) is defective.
Note:Connector assignments with key F7End of test













NO
Ambient temperature
The temperature difference is not greater than 40 °C.End of test

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