Control Unit 12v for Eberspacher Airtronic B4 - 225101003015

Control block.

Errors and description of actions when they occur:

74 * Faulty control unit

• The overheating threshold is not detected by the control unit -> replace the control unit.

90 Faulty control unit (internal fault)

• Replace the control unit.

91 External interference voltage

• Malfunctions of the control unit due to voltage disturbances in the on-board network. Possible reasons: The battery is discharged, the charger is -> eliminate the interference voltage.

92 Faulty control unit (ROM fault)

• Replace the control unit.

93 * Defective control unit

• Replace the control unit.

94 Faulty control unit (EEPROM fault)

• Replace the control unit.

95 * Defective control unit

• Replace the control unit.

96 Faulty internal temperature sensor

• Replace the control unit or use an external temperature sensor.

97 Faulty control unit

• Replace the control unit.

98 * Defective control unit

• Replace the control unit.

99 * Defective transistor in the control unit

Check the control unit with a diagnostic device if it is OK -> check the cable harness of external components for correct installation and for damage, if it is OK -> check the cable harness for permeability if it is OK -> replace the control unit.

* This DTC or resistance value is displayed only when using a new generation control device. It differs from the previous control unit of the cable bundle in the winding and the laterally mounted temperature sensor, which is visible when the cover is removed.

Dismantling the control unit

Open both latches, lift the cover and remove it forwards.

ATTENTION! 

The cover of the heater must be removed when performing all phases of repair work. 
If necessary, wait for the device to cool. Hole for cable harness outlet on the housing of choice, left or right.

• Unscrew the fixing screw. 
• Tighten the clamp. 
• Remove the control unit upwards. 
• Disconnect the wires from the holders on the control unit (observe the position of the wires) 
• Remove the sleeve from the outer casing (bottom). 
• Remove the plug from the control unit - now you can remove the control unit.

ATTENTION!

When mounting the control unit, make sure that the wires are fixed in the holder on the 
control unit and the plug is inserted into the control unit (do not mix it up). 
Tightening torque of the mounting screw Pos. 1: 2 +0.2 Nm.

Check control unit.

An EDiTH maintenance program is required to check the control unit in a dismantled state.