The control signal to the cab fan (M3) is short circuit to battery.
â–¶ How to fix
Check the control signal cable harness.
What you'll see
No driver-visible symptom recorded.
System reaction
The cab fan will run at full speed.
Diagnostic depth
Detection
The climate control system (E17) has detected that the control signal is stuck at high level, when it should be a PWM signal. The test is performed when the cab fan is not running at full speed and the starter motor (M1) is not running.
Possible cause
The control signal cable harness is short circuit to battery.