DM-TL (diagnosis Module - Tank Leakage)

A new Fuel System Leak Diagnosis Pump is equipped on the M5. The pump will eventually replace the current vacuum LDP on all vehicles.

The pump is manufactured by Bosch to BMW specifications.

• Bosch ECMs identify the electrical function of the pump as DM-TL.
• Siemens ECMs identify the electrical function as "LDP-M1".

Fig 1: Identifying DM-TL (Diagnosis Module - Tank Leakage)

Courtesy of BMW OF NORTH AMERICA, INC.

Functional Overview: 

The DM-TL is located in the drivers side rear wheel well in the M5.

1. In it's inactive state, filtered fresh air enters the evaporative system through the sprung open valve of the DM-TL.
2. When the DME activates the DM-TL for leak testing, it first activates only the pump motor. This pumps air through a restricter orifice (1.0 or 0.5 mm) which causes the electric motor to draw a specific amperage value. This value is equivalent to the size of the restricter.
3. The solenoid valve is then energized which seals the evap system and directs the pump output to pressurize the evap system.

The evap system is detected as having a large leak if the amperage value is not realized, a small leak if the same reference amperage is realized or no leak if the amperage value is higher than the reference amperage.

Fig 2: Identifying EVAP System

Courtesy of BMW OF NORTH AMERICA, INC.