Sep 21, 2020 (1 month ago)
Could be this .
Increased idle speed
Customer complains of an increased idle speed up to 1150 rpm.
Increased idle speed signal is managed by the engine ECU but based on a signal coming from the BCM
(Body Control Module).
If the state of charge (SOC) for the battery is too low the BCM urges the engine ECU to increase idle
speed in order reload the battery in a proper way. There are three possible idle speed steps going from:
-- step 1 (= 925 rpm) to
-- step 2 (= 1000 rpm-1050 rpm) and
-- step 3 (= 1100 rpm-1150 rpm)
The step is dependent on the SOC as well as the outside temperature, which also affects the SOC.
Other possible reasons for increased idle speed also managed by the engine ECU based on a BCM
a.) During auxiliary heater on the idle speed will be set to step 2.
b.) During HVAC operation the idle speed will be set to step1-3 based on the thermal load.
c.) During DPF regeneration mode the idle speed will be set to step1-3 based on the engine
In case of customer complaint please explain this technical content to the customer.