P0726
The input signal of the engine speed has a malfunction. (P0726)
Possible cause:
- B70 (Crankshaft Hall sensor)
- Smooth engine running
Affected functions:
- Engine diagnosis
-------------------------------------------------
Test 1: Check smooth engine running.
Test 2: Check component B70 (Crankshaft Hall sensor).
1. Check smooth engine running.
Test 1.1: Check self-adaptation of mixture formation. ( Check by means of actual values )
Test 1.2: Check water and diesel content in gasoline fuel. (Fuel quality)
Test 1.3: Test fuel pressure and delivery of component M3 (Fuel pump).
Test 1.4: Compression test
1.1. Check self-adaptation of mixture formation. ( Check by means of actual values )
Warning!Communication with ECU required.
1.2. Check water and diesel content in gasoline fuel. (Fuel quality)
Safety note
Warning!Risk of explosion, poisoning and injury!Fuels are highly inflammable and toxic if inhaled. Fuels may cause skin damage. fuel vapors are explosive, invisible and spread out at floor level, they are toxic if inhaled and produce giddiness and an anaesthetizing effect.Rules of conduct and protective measures
- Wear suitable protective clothing.
- Pay attention to national safety precautions and regulations.
- No fire, sparks, naked flames and smoking.
- Ensure the work place is adequately ventilated.
- Never drain or pour in fuels over assembly pits.
- Store drained fuel in a suitable and sealed vessel.
- Immediately eliminate any fuel which has flowed out.
First-aid measures
- Clean moistened skin with water and soap.
- Change moistened clothing as quickly as possible.
- If fuel gets into your eyes, rinse out your eyes immediately with water and contact a doctor if necessary.
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Check proportion of water in gasoline fuel.
Figure legend
- 043Pressure gage
- 055Measuring beaker
- 069Pressure hose(119 589 04 63 00)
Test sequence
- Switch off ignition.
- Connect test pressure gauge.
- Hold the open fuel line in measuring beaker (055).
- Switch on ignition.
- Insert bridge.:
- Bridge between sockets (F.2) 98 and (F.17) 113 of the 126-pole socket box tester.
- Component M3 (Fuel pump) runs.
- Drain off about 0.5 l fuel.
- Remove bridge.
Specified value
- Testing If water is present in the fuel, the fuel is cloudy.After being left for a few hours, the water settles on the bottom of the measuring beaker.
- In cases of doubt, compare the fuel drained with proper fuel.
Question
- Was the test o.k.?
YES
Check proportion of diesel in gasoline fuel.
Test sequence
- Allow a few drops of the drain fuel to drip onto a sheet of paper.
Specified value
- Testing The fuel should evaporate within a few minutes practically free of stains.If diesel portions are present in the fuel, a clearly visible oil stain remains after the gasoline has evaporated.
- In cases of doubt, compare the fuel drained with proper fuel.
Question
- Was the test o.k.?
YES
The test was okay.End of test
NO
The test was not okay.Possible cause and remedy
- Diesel is present in the gasoline fuel.Replace the fuel.
End of test
NO
The test was not okay.Possible cause and remedy
- Water is present in the fuel.Replace the fuel.
1.3. Test fuel pressure and delivery of component M3 (Fuel pump).
Safety note
Warning!Risk of explosion, poisoning and injury!Fuels are highly inflammable and toxic if inhaled. Fuels may cause skin damage. fuel vapors are explosive, invisible and spread out at floor level, they are toxic if inhaled and produce giddiness and an anaesthetizing effect.Rules of conduct and protective measures
- Wear suitable protective clothing.
- Pay attention to national safety precautions and regulations.
- No fire, sparks, naked flames and smoking.
- Ensure the work place is adequately ventilated.
- Never drain or pour in fuels over assembly pits.
- Store drained fuel in a suitable and sealed vessel.
- Immediately eliminate any fuel which has flowed out.
First-aid measures
- Clean moistened skin with water and soap.
- Change moistened clothing as quickly as possible.
- If fuel gets into your eyes, rinse out your eyes immediately with water and contact a doctor if necessary.
Test 1.3.1: Test fuel pressure and internal leaks of fuel system.
Test 1.3.2: Test delivery of component M3 (Fuel pump).
Test 1.3.3: Test current consumption of component M3 (Fuel pump).
Test 1.3.4: Test current consumption of component N10/2kA (Fuel pump relay).
1.3.1. Test fuel pressure and internal leaks of fuel system.
Question
- Can the vehicle engine be operated at idle speed?
YES
Figure legend
- 043Pressure gage(103 589 00 21 00)
- 055Measuring beaker
- 069Pressure hose(119 589 04 63 00)
Warning!On USA vehicles with code 917 ( PZEV ), the sealing ring of the service valve for the protective cap must be replaced.Test sequence
- Switch off ignition.
- Connect test pressure gauge.
- Engine at idle
Specified value
- Pressure[3.7...4.2] bar
Question
- Is the measurement value OK?
YES
The measurement value is OK.Test prerequisite
- Test pressure gage is connected.
Test sequence
- Run the engine for a short time and switch off again.
- Switch off ignition.
Specified value
- Pressure after 30 minutes:[> 2.5] bar
Question
- Is the measurement value OK?
YES
The measurement value is OK.Further possible causes of fault
- Test delivery of component M3 (Fuel pump).
NO
The measurement value is not OK.Possible cause and remedy
- In the event of slow pressure drop:Check component Y62 (Fuel injectors).
- In the event of rapid pressure drop:Check valve in component M3 (Fuel pump)
NO
The measurement value is not OK.Possible cause and remedy
- Test current consumption of component M3 (Fuel pump).
- Fuel filter with integrated pressure regulator
NO
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Figure legend
- 043Pressure gage
- 055Measuring beaker
- 069Pressure hose(119 589 04 63 00)
Warning!On USA vehicles with code 917 ( PZEV ), the sealing ring of the service valve for the protective cap must be replaced.Test sequence
- Switch off ignition.
- Connect test pressure gauge.
- Connect socket box (126-pin) to component N3/10 (ME-SFI [ME] control unit).
- Insert bridge.:
- Bridge between sockets [F.4] 100 and [F.17] 113 of the 126-pole socket box tester.
- Switch on ignition.
- Component M3 (Fuel pump) runs.
- Warning! Insert bridge only for a short time.
Specified value
- Pressure[3.7...4.2] bar
Question
- Is the measurement value OK?
YES
The measurement value is OK.Test prerequisite
- Test pressure gage is connected.
Test sequence
- Switch off ignition.
- Insert bridge.:
- Bridge between sockets [F.2] 98 and [F.17] 113 of the 126-pole socket box tester.
- Switch on ignition.
- Component M3 (Fuel pump) runs.
- Switch off ignition.
- Remove bridge.
Specified value
- Pressure after 30 minutes:[> 2.5] bar
Question
- Is the measurement value OK?
YES
The measurement value is OK.Further possible causes of fault
- Test delivery of component M3 (Fuel pump).
NO
The measurement value is not OK.Possible cause and remedy
- In the event of slow pressure drop:Check component Y62 (Fuel injectors).
- In the event of rapid pressure drop:Check valve in component M3 (Fuel pump)
NO
The measurement value is not OK.Possible cause and remedy
- N10/2f4 (Fuse 4)
- N10/2kA (Fuel pump relay)
- Test current consumption of component M3 (Fuel pump).
- Fuel filter with integrated pressure regulator
1.3.2. Test delivery of component M3 (Fuel pump).
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Figure legend
- 055Measuring beaker
Test sequence
- Switch off ignition.
- Connect socket box (126-pin) to component N3/10 (ME-SFI [ME] control unit).
- Separate fuel feed hose at the fuel line and hold in a suitable measuring beaker.
- Insert bridge.:
- Bridge between sockets [F.4] 100 and [F17] 113 of the 126-pole socket box tester.
- Switch on ignition.<-->Component M3 (Fuel pump) runs.
Specified value
- 1 liters of fuel should flow in a maximum of 20 seconds.
Question
- Is the measurement value OK?
YES
The measurement value is OK.End of test
NO
The measurement value is not OK.Possible cause and remedy
- Inspect fuel lines for restriction points (in particular pinching).
- Fuel filter
- Test current consumption of component M3 (Fuel pump).
1.3.3. Test current consumption of component M3 (Fuel pump).
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Figure legend
- 003Multimeter
- N10/2f3 (Fuse 3)
- N10/2kA (Fuel pump relay)
Test prerequisite
- Carry out test only if complaint exists.
Test sequence
- Switch off ignition.
- Insert bridge.:
- Bridge between sockets [F.4] 100 and [F.17] 113 of the 126-pole socket box tester.
- Unplug component N10/2f3 (Fuse 3) from component N10/2 (Rear SAM control unit with fuse and relay module).
- Measurement is performed at the contact slot of component N10/2f3 (Fuse 3).
- Measure direct current with multimeter between sockets [F10f3] -.- and [F10f3] -.-
- Switch on ignition.
- Component M3 (Fuel pump) runs.
Specified value
- Amperage[4...9] A
Question
- Is the measurement value OK?
YES
The measurement value is OK.Further possible causes of fault
- M3 (Fuel pump)
End of test
NO
The measurement value is not OK.Possible cause and remedy
- N10/2f4 (Fuse 4)
- Test cables
- M3 (Fuel pump)
End of test
1.3.4. Test current consumption of component N10/2kA (Fuel pump relay).
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Test sequence
- Switch off ignition.
- Connect socket box (126-pin) to component N3/10 (ME-SFI [ME] control unit).
- Measure direct current with multimeter between sockets [F.4] 100 and [F.17] 113 of the 126-pole socket box tester.
- Switch on ignition.
Specified value
- Amperage[0,1...0,3] A
- Component M3 (Fuel pump assembly) is switched on and is heard to run.
Question
- Is the measurement value OK?
YES
The test was okay.End of test
NO
The measurement value is not OK.Possible cause and remedy
- Lines to component N10/2kA (Fuel pump relay)
- N10/2kA (Fuel pump relay)
End of test
1.4. Compression test
Test prerequisite
- Connect battery charger.
- Ignition ON
- Engine not running
- Coolant temperature between 70° C and 90° C
Actual values:
- Coolant temperature:Warning! Communication with ECU required.
Note
- If the rpm difference is greater than 28 1/min, a cylinder leak test must be performed on all cylinders as per the repair instructions to pinpoint the fault.
Proceed to 'Actuation' with F2
2. Check component B70 (Crankshaft Hall sensor).
Test 2.1: Test signal voltage of component B70 (Crankshaft Hall sensor).
Test 2.2: Check power supply of component B70 (Crankshaft Hall sensor).
2.1. Test signal voltage of component B70 (Crankshaft Hall sensor).
Test 2.1.1: The engine does not start.
Test 2.1.2: Engine running
2.1.1. The engine does not start.
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Settings
- Trigger level: 50 %
- Time range: 5 ms
Test sequence
- Switch off ignition.
- Connect socket box (126-pin) to component N3/10 (ME-SFI [ME] control unit).
- Observe oscilloscope pattern between sockets (M.80) 80(A7) and (M.81) 81(A4) of the 126-pole socket box tester.
- Start engine.
Specified value
- Measuring system
Warning!The rising signal edge in the gap (see arrow) may vary.Note
- Measuring system:Communication with ECU required
2.1.2. Engine running
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Settings
- Trigger level: 50 %
- Time range: 5 ms
Test sequence
- Switch off ignition.
- Connect socket box (126-pin) to component N3/10 (ME-SFI [ME] control unit).
- Observe oscilloscope pattern between sockets (M.80) 80(A7) and (M.81) 81(A4) of the 126-pole socket box tester.
- Operate engine at idling speed.
Specified value
- Measuring system
- Signal (4,7 - 5,3) V
Warning!The rising signal edge in the gap (see arrow) may vary.Note
- Measuring system:Communication with ECU required
2.2. Check power supply of component B70 (Crankshaft Hall sensor).
Figure legend
- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!
- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2
Test sequence
- Measure direct voltage with multimeter between sockets (M.80) 80 and (M.44) 44 of the 126-pole socket box tester.
- Switch on ignition.
Specified value
- Voltage[4.8...5.3] V
Question
- Is the measurement value OK?
YES
The measurement value is OK.Possible cause and remedy
- Signal wire
- B70 (Crankshaft Hall sensor)
End of test
NO
The measurement value is not OK.Possible cause and remedy
- Lines to component B70 (Crankshaft Hall sensor)
End of test