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Home >> Mercedes Benz >> 2005 >> CLK 320 (209.365) V6-3.2L (112.955) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P20D4 >> The Load Limit Is Active >> Part 3

Part 3




The Load Limit is Active

Test 1 Check Self-adaptation of Mixture Formation
Test 2 Check Component B2/5 (Hot Film MAF Sensor)
Test 3 Check Component B2/5b1 (Intake Air Temperature Sensor)
Test 4 Check Component M16/6 (Throttle Valve Actuator)



2 Check Component B2/5 (Hot Film MAF Sensor)

Test 2-1 Test Signal Voltage of Component B2/5 (Hot Film MAF Sensor) By Means Of Actual Value.
Test 2-2 Test Voltage Supply of Component B2/5 (Hot Film MAF Sensor).


2-1 Test Signal Voltage of Component B2/5 (Hot Film MAF Sensor) By Means Of Actual Value.

Test requirement
- Battery voltage is o.k..
- The 5 voltage supply of component B2/5 (Hot film MAF sensor) is OK.
- The 12 voltage supply of component B2/5 (Hot film MAF sensor) is OK.
- Engine not running
- Ignition ON

Status of relevant actual value:
- HFM-SFI voltage: Note! Communication with ECU required

Specified value:
- Voltage [0,980...1,030] V

Question
- Are the measured values okay?
Yes
The actual values are okay.
Possible cause and remedy
- Check assignment of component B2/5 (Hot film MAF sensor) to engine model designation.
No
The measured values are not o.k.
Possible cause and remedy
- Test voltage supply of component B2/5 (Hot film MAF sensor).
- Inspect cables from component N3/10 (ME-SFI control module) to component B2/5 (Hot film MAF sensor).
- B2/5 (Hot film MAF sensor)

** End of Test **


2-2 Test Voltage Supply of Component B2/5 (Hot Film MAF Sensor).


Test 2-2-1 Test Voltage Supply 5V of Component B2/5 (Hot Film MAF Sensor).
Test 2-2-2 Test Voltage Supply 12V of Component B2/5 (Hot Film MAF Sensor).


2-2-1 Test Voltage Supply 5V of Component B2/5 (Hot Film MAF Sensor).





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

Test sequence
- Switch off ignition.
- Detach the socket at the component B2/5 (Hot film MAF sensor).
- (B2/5) 3 <--> 4 (B2/5)
- Switch on ignition.

Specified value
- Voltage[4.75...5.25] V

Question
- Is the measured value okay?
Yes
The measured value is o.k. ** End of test **
No
The measured value is not o.k. Possible cause and remedy : Test voltage supply of component B2/5 (Hot film MAF sensor). Test voltage supply of the following components for short circuit:
- B28 (Intake manifold pressure sensor)
- B37 (Accelerator pedal sensor)
- B40 (Oil sensor (oil level, temperature and quality))
- M16/6 (throttle valve actuator)
- B4/3 (Fuel tank pressure sensor)(only )

** End of Test **


2-2-2 Test Voltage Supply 12V of Component B2/5 (Hot Film MAF Sensor).





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

Test sequence
- Switch off ignition.
- Detach the socket at the component B2/5 (Hot film MAF sensor).
- (B2/5) 3 <--> 2 (B2/5)
- Switch on ignition.

Specified value
- Voltage[11.0...14.5] V

Question
- Is the measured value okay?
Yes
The measured value is o.k.
Further possible causes of fault
- Unmetered air
- Signal wire
- B2/5 (Hot film MAF sensor)
No
The measured value is not o.k.
Possible cause and remedy
- Cable for voltage supply

** End of Test **


3 Check Component B2/5b1 (Intake Air Temperature Sensor)

Test 3-1 Check Component B2/5b1 (Intake Air Temperature Sensor) Using Actual Value.
Test 3-2 Check Plausibility of Actual Value B2/5b1 (Intake Air Temperature Sensor) in Control Module N3/10 (ME-SFI Control Module).
Test 3-3 Test Voltage Supply of Component B2/5b1 (Intake Air Temperature Sensor).
Test 3-4 Test Internal Resistance of Component B2/5b1 (Intake Air Temperature Sensor).


3-1 Check Component B2/5b1 (Intake Air Temperature Sensor) Using Actual Value.

Test sequence
- Switch on ignition.

Status of relevant actual value:
- B2/5b1 (Intake air temperature sensor): Note! Communication with ECU required

Specified value
- Current temperature in area surrounding component B2/5b1 (Intake air temperature sensor)

Question
- Is the actual value o.k.?
Yes
The actual value is okay. ** End of Test **
No
The actual value is not o.k.
Possible cause and remedy
- Check plausibility of actual value B2/5b1 (Intake air temperature sensor) in control module N3/10 (ME-SFI control module).
- Test voltage supply of component B2/5b1 (Intake air temperature sensor).
- Test internal resistance of component B2/5b1 (Intake air temperature sensor).

** End of Test **


3-2 Check Plausibility of Actual Value B2/5b1 (Intake Air Temperature Sensor) in Control Module N3/10 (ME-SFI Control Module).





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

Test sequence
- Detach socket at component B2/5 (Hot film MAF sensor).
- Switch on ignition.

Status of relevant actual value:
- B2/5b1 (Intake air temperature sensor): Note! Communication with ECU required

Specified value
- °C If the connection is unplugged at component B2/5b1 (Intake air temperature sensor) , the value is approx. [ ].
- Bridge pin 1 in pin 3 at the unplugged connection of component B2/5b1 (Intake air temperature sensor).150 °C The value is approx. [ ].

Question
- Is the actual value o.k.?
Yes
The actual value is okay.
Further possible causes of fault
- Test voltage supply of component B2/5b1 (Intake air temperature sensor).
- Test internal resistance of component B2/5b1 (Intake air temperature sensor).
No
The actual value is not o.k.
Possible cause and remedy
- Signal wire

** End of Test **


3-3 Test Voltage Supply of Component B2/5b1 (Intake Air Temperature Sensor).





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

Test sequence
- Switch off ignition.
- Detach the socket at the component B2/5 (Hot film MAF sensor).
- (B2/5) 3 <--> 4 (B2/5)
- Switch on ignition.

Specified value
- Voltage[4.75...5.25] V

Question
- Is the measured value okay?
Yes
The measured value is o.k.
Further possible causes of fault
- Test signal voltage of component B2/5b1 (Intake air temperature sensor).
- Test internal resistance of component B2/5b1 (Intake air temperature sensor).
No
The measured value is not o.k.
Possible cause and remedy
- Cable for voltage supply

** End of Test **


3-4 Test Internal Resistance of Component B2/5b1 (Intake Air Temperature Sensor).





Test sequence
- Switch off ignition.
- Detach the socket at the component B2/5 (Hot film MAF sensor).
- (B2/5) 1 <--> 3 (B2/5)

Specified value
- Resistor(20 °C ): [2350...2500] ohms
- Resistor(30 °C ): [1600...1700] ohms
- Resistor(40 °C ): [1100...1200] ohms
- Resistor(50 °C ): [800...900] ohms

Question
- Are the measured values okay?
Yes
The measured values are o.k. ** End of Test **
No
The measured values are not o.k.
Possible cause and remedy
- B2/5b1 (Intake air temperature sensor)

** End of Test **


4 Check Component M16/6 (Throttle Valve Actuator)

Test 4-1 Check Component M16/6 (Throttle Valve Actuator) Using Actual Value.
Test 4-2 Test Component M16/6m1 (Actuator Motor) by Actuation.
Test 4-3 Test Internal Resistance of Component M16/6m1 (Actuator Motor).
Test 4-4 Test Internal Resistance of Component M16/6 (Throttle Valve Actuator).
Test 4-5 Test Voltage Supply of the Potentiometers of Component M16/6 (Throttle Valve Actuator).


4-1 Check Component M16/6 (Throttle Valve Actuator) Using Actual Value.

Test requirement
- Ignition ON

Status of the relevant actual values:
- M16/6 (throttle valve actuator) Signal 1: Note! Communication with ECU required
- M16/6 (throttle valve actuator) Signal 2: Note! Communication with ECU required

Specified values
- M16/6 (throttle valve actuator)Signal 1(Accelerator not operated): [0.30...0.90] V
- M16/6 (throttle valve actuator)Signal 2(Accelerator not operated): [4.20...4.60] V
- M16/6 (throttle valve actuator)Signal 1(Kickdown switch operated, accelerator fully depressed):[1.30...1.70] V
- M16/6 (throttle valve actuator)Signal 2(Kickdown switch operated, accelerator fully depressed):[3.30...3.70] V

Question
- Are the actual values o.k.?
Yes
The actual values are okay. ** End of Test **
No
At least one of the relevant actual values is not okay.
Possible cause and remedy
- Test internal resistance of component M16/6 (throttle valve actuator).
- Test voltage supply of component M16/6 (throttle valve actuator).

** End of Test **


4-2 Test Component M16/6m1 (Actuator Motor) by Actuation.

Test requirement
- The engine is running.

Note
- If the throttle valve angle is < 1,1� DK, there is unmetered air present.

Note: Component M4/3 (engine/AC electric suction fan) runs with an on/off ratio of 50 % during the actuations for safety reasons.

Note! Communication with ECU required.


4-3 Test Internal Resistance of Component M16/6m1 (Actuator Motor).





Test sequence
- Switch off ignition.
- Unplug the socket 1 at component N3/10 (ME-SFI control module).
- (N3/10) 1.6 <--> 1.3 (N3/10)

Specified value
- Resistor[1...10] ohms

Question
- Is the measured value okay?
Yes
The measured value is o.k. ** End of Test **
No
The measured value is not o.k.
Possible cause and remedy
- Wiring between N3/10 (ME-SFI control module) and M16/6m1 (Actuator motor)
- M16/6m1 (Actuator motor)

** End of Test **


4-4 Test Internal Resistance of Component M16/6 (Throttle Valve Actuator).





Test requirements
- The throttle flap of component M16/6 (throttle valve actuator) should operate freely and must not stick or rub.
- At least one of the relevant actual values is not okay.

Test sequence
- Switch off ignition.
- Remove air scoop at component M16/6 (throttle valve actuator).
- Unplug the socket 3 at component N3/10 (ME-SFI control module).

M16/6r3 (Actual value potentiometer (sliding contact 1))
- (N3/10) 3.21 <--> 3.22 (N3/10)
- Slowly operate throttle flap by hand up to full load.

Specified values
- Idle speed[ca. 1380] ohms
- Full load[ca. 480] ohms

M16/6r4 (Actual value potentiometer (sliding contact 2))
- (N3/10) 3.20 <--> 3.22 (N3/10)
- Slowly operate throttle flap by hand up to full load.

Specified values
- Idle speed[ca. 650] ohms
- Full load[ca. 1490] ohms

Question
- Are the measured values okay?
Yes
The measured values are o.k.
Further possible causes of fault
- Test voltage supply of the potentiometers of component M16/6 (throttle valve actuator).
No
The measured values are not o.k.
Possible cause and remedy
- Leads to component M16/6 (throttle valve actuator)
- M16/6 (throttle valve actuator)

** End of Test **


4-5 Test Voltage Supply of the Potentiometers of Component M16/6 (Throttle Valve Actuator).

Test requirement
- At least one of the relevant actual values is not okay.

Test sequence
- Switch off ignition.
- Unplug the socket 3 at component N3/10 (ME-SFI control module).
- Connect adapter cable no. 210 589 05 63 at component N3/10 (ME-SFI control module).
- (N3/10) 3.19 <--> 3.22 (N3/10)
- Switch on ignition.

Specified value
- Voltage[4.75...5.25] V

Question
- Is the measured value okay?
Yes
The measured value is o.k.
Possible cause and remedy
- Inspect cables from component M16/6 (throttle valve actuator) to component N3/10 (ME-SFI control module).
No
The measured value is not o.k.
Possible cause and remedy
- N3/10 (ME-SFI control module)

** End of Test **
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