Micro Autonomations LLC – Fan Controller v3
5
Document Rev 1.0
Signal Descriptions
Switched 12v – Red - 1
Main power input to the controller. This must be from a switched source so the controller is off when
the vehicle is off and during cranking. A 5 amp inline fuse is recommended.
Ground – Black - 6
Main ground for the controller. This must have a good connection to ground. This should be wired such
that it is near the main ground point near the battery. The engine ground strap, and the ground for the
fan, should also be located in the same spot.
Note:
Power and Ground to the fan are separate from the controller power and ground, and should include an
inline 50A fuse/breaker minimum
Trigger Output – Green - 2
This is the On/Off signal to the Mercedes Fan. Do not apply any external voltage or ground to this pin.
Do not reverse this wire with the Speed wire. This signal is required for the fan to operate.
Speed Output – Yellow - 7
This is the variable duty cycle speed signal to the Mercedes Fan. Do not apply any external voltage or
ground to this pin. Do not reverse this wire with the Trigger wire. This signal is required for the fan to
operate.
Air Conditioning Input – Brown - 3
This input indicates that the air conditioning (AC) system is operating, and that the fan should be turned
on. This pin may be either grounded, or tied to +12v by the air conditioning system, typically through
the trinary switch. This may also be controlled by a switch to manually turn the fan on. There is a 5
second delay after this signal is active before the fan turns on, and another 5 second delay before it is
turned off. When activated, the fan will operate at 50%. If the engine temperature requires it, fan
speed will automatically increase above 50%.
Note:
This input is optional, and may be left unused.
Standalone Temperature Sensor (+) – Orange - 4
Two Terminal Temperature Sensor
– Either terminal may go on this pin. The other terminal
should go to Standalone Temperature Sensor Return (GND).
Single Terminal Temperature Sensor
– The one terminal must go to this pin. The body of the
sensor must have a good connection to ground.
