SEAL AS 9X4584 - Caterpillar

Proper welding procedures are necessary in order to avoid damage to the A4 Electronic Control Module (ECM), A5 ECM, Diesel Exhaust Fluid Control Unit (DCU) if equipped, sensors, and associated components. Also consider components that are for the driven equipment. Remove the component that requires welding. When welding on an engine that is equipped with an ECM and removal of the component is not possible, the following procedure must be followed. This procedure provides the minimum amount of risk to the electronic components.
Stop the engine. Remove the electrical power from the ECM.
Ensure that the fuel supply to the engine is turned off.
Disconnect the negative battery cable from the battery. If a battery disconnect switch is installed, open the switch.
Disconnect all electronic components from the wiring harnesses. Electronic components include the following components:
Electronic components for the driven equipment
A4 ECM
A5 ECM
DCU
Sensors
Do NOT use electrical components (ECM or sensors) or electronic component grounding points for grounding the welder.
Illustration 1 g01143634
Service welding guide (typical diagram)
When possible, connect the welder ground clamp directly to the engine component that will be welded. Place the clamp as close as possible to the weld. A close connection will reduce the possibility of welding current damage to the engine bearings, to the electrical components, and to other components.
Protect the wiring harnesses from welding debris and/or from the welding spatter.
Use standard welding procedures to weld the materials together.