W251 R-Class EGR Issues

[ber5ien]

I checked the connector with the rear probe with the ignition on.
I think I should expect two 12V cables or at least one.
Is there a short circuit somewhere?

5 pin 533mV
4 pin 0.8mV
3 pin 5V
2 pin 261mV
1 pin 261mV

Disconnected plug:

5 pin 4.1V
4 pin 8mV
3 pin 5V
2 pin 12+V
1 pin 32mV

I checked the EGR ground again and found that the positive battery terminal had 12V so the ground was good.

 

[Mersovod]

You have a 12V drop when connecting a load. Search here. In the future, specify the VIN. The diagrams may differ.
The plug is connected!

 

[ber5ien]

Should I check to see if one of the cables has come loose causing an open circuit and if the EGR valve is leaking 12V somewhere else after being connected?

 

[Mersovod]

Unwind the wiring, check the Z-shaped couplings and the wire to the ECU.

 

[ber5ien]

Unfortunately, this wiring is designed for 3 contacts, and I have 5.
I checked the wiring harness, they seem to be fine.
Someone had damaged these cables, but I checked the one that looked damaged and it was fine inside.
Why does the ECU disconnect 12V from the EGR?

 

[Mersovod]

5 pins and 3 wires, this is normal. The control unit will cut off the output power if it detects a short circuit or no load. Check all engine wiring, sometimes it wears out and shorts to ground. X25/2 also hangs on F105 F58. And try to disconnect the connector from the fuel filter heater, ventilation, M55 one by one and check the power supply. In general, disconnect components from terminal 87 one by one until you find the culprit of the short circuit.

 

[Mersovod]

Wiring diagram for 5 wires in 2011 W251 model. Z14 powers 3 components. Power supply from N3/9 M (pin 56) colored wires GYBK and RDBK.

• B70 Crankshaft Hall sensor
• B6/1 Camshaft Hall sensor
• Y27/9 Left exhaust gas recirculation positioner

 

[Mersovod]

When you remove the EGR connector, there should be nothing on pin 5. This means that wires 3 and 5 have a short circuit. There are only two power supplies, 12 V and 5 V, you have 3.

 

[ber5ien]

Thanks for the info. Should I try disconnecting these sensors first or try removing this pin from the plug? So that leaves only 4 pins to check?

 

[Mersovod]

No. Disconnect plug M from N3/9 and Y27/9 and check wires GYBK and BUWH for short circuit.