Air Mass Meter (HLM)

Air mass meter (HLM):

Check HLM signal:

•D• 200 - The load signals provides an indication relating to the measured air throughput in the HLM, see - Technical Data - for idle speed value. When air is injected in the HLM, the load signal can be seen to change when the engine is stationary.

Check 12 V voltage supply at the HLM Pin 2(+) and 4(-). Measure hotwire resistance at Pin 5(+) and 3(-). For technical data, see - Technical Data -.

Check burn-clear function:

Increase engine speed once to above 200 rpm (engine temperature >60° C). After switching off the engine, a voltage increase to approx. 3.5 V can be measured at the HLM between connection 1 (+) and 5(-).