P1482

P1482

DMTL - Tank Leakage Diagnostics Module, heater output stage

Diagnostic conditions
- Supply voltage 10 V ... 16 V
- Engine start

Possible fault causes
- Open circuit, short circuit to B+ or short circuit to ground of activation line for DMTL heater
- Open circuit in the power supply to the DMTL
- DMTL - Tank Leakage Diagnostics Module faulty
- DME control module faulty

Function description

Tank leakage test/DMTL - Tank Leakage Diagnostics Module

NOTE: The tank leakage test is performed only on USA vehicles.

Construction of the tank leakage diagnostics module:
The diagnostics module consists of an electric motor with a small air pump, switch-over valves and a reference nozzle.
In addition, the module is heated so as to prevent the forming of condensation and ice.

Procedure of the function:
- The pump is operated via an electric motor and conveys air through the reference leak. The power consumed during this process is determined.
- The switch-over valve switches and the air current is now directed into the fuel tank. The power consumed during this process is also determined. After a waiting period dependent on the fuel tank fuel level, it must be at least as high as the power consumption was during the reference leak test if the tank system is leak-free.
- The system is identified to by leaking if the power consumption is lower during the actual leakage test as it was during the reference leak test.
- An evaluation of the power consumption levels when the pump is started and after the switch-over valve has switched serves to identify faults within the tank leakage diagnostic module (e.g. pump blocked, motor spins at idle speed, valve does not switch etc.).
- The diagnosis of heating, motor and switch-over valve is performed via the output stage of the DME control module.