Control unit without protective housing
Note: If the engine control unit is being replaced, connect a tester to the vehicle and carry out the function "Replacing the control unit", If the engine control unit contacts the positive pole of the battery, the control unit fails.
Release retainer in -direction of arrow- and remove control unit -1-. Unlock and disconnect connectors for engine control unit -J623-.
Installation
Installation in reverse order. After installing the engine control unit, the following work must be performed. Connect tester. Activate the control unit in "SWM" mode" and "Guided functions", function "Change control unit".
Control unit with protective housing
Note: If the engine control unit is to be replaced, connect a tester to the vehicle and carry out the "Change control unit" function".
Release shear bolts -arrows- for removing protective housing -1- as follows.
Cut through the head of the shear bolt -1- with a screwdriver slot -2-.
Note: The threads of the shear bolts are coated with threadlocker. Heating the shear bolt when grinding the slot for a screwdriver makes it easier to unscrew it. If shear bolts do not come out, heat them up with a heat gun.
Heating shear bolts with an industrial hair dryer
Set the temperature setting potentiometer -2- to the maximum heat output and the air volume on/off switch -3- to position 3.
Heat the head of the shear bolt -1 for about 20-30 seconds.
Further, if the bolts are loose: Unscrew shear bolt -1- with a screwdriver -2-.
Remove protective housing -1-.
Attention! If the engine control unit contacts the positive pole of the battery, the control unit fails.
Release retainer in -direction of arrow- and remove control unit -1-. Unlock and disconnect connectors. engine control unit -J623-.
Installation
Installation in reverse order. Always close the engine control unit -J623- with protective cover again. Clean the threaded holes for the new shear bolts to remove any remaining threadlocker. You can clean the thread with a tap. Use new shear screws when installing. After installing the engine control unit, the following work must be performed. Connect tester. Activate the control unit in "SWM" mode" and "Guided functions", function "Change control unit".