Ignition Control Module

This procedure replaces the ignition control module on a 2019 Mercedes-Benz G-Class with the 4.0L Turbo V8 engine, including removal of engine covers, disconnection of electrical connections, and installation of the new module.

Warnings

Tools required

Parts

• Ignition control module × 1 — A0009063503 or equivalent
• Thermal paste/compound × 1 — Use Mercedes-Benz approved thermal compound

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure engine is completely cool to the touch
3. Open hood and secure in raised position
4. Disconnect battery negative terminal and wait 10 minutes
5. Photograph engine bay layout and all electrical connections for reference

Procedure

1. 1

   Remove Engine Cover Assembly
   Locate and remove the plastic engine cover assembly. The cover is secured by multiple quick-release fasteners and rubber grommets. Grasp the cover firmly at the front edges and pull upward with steady pressure to release the grommets from their posts. Lift the cover away from the engine bay and set aside.
2. 2

   Remove Air Intake Components
   Disconnect the air intake duct from the throttle body by loosening the hose clamp. Release the wiring harness clips along the intake duct. Remove the air filter housing cover by releasing the spring clips on both sides. Lift out the air filter element and set aside. Remove the lower air filter housing by releasing the mounting tabs and lifting upward. This provides access to the ignition control module area.
3. 3

   Locate Ignition Control Module
   The ignition control module is mounted on the driver's side (left side when facing the vehicle) of the engine compartment, typically near the firewall or on the inner fender area. It is a rectangular metal-cased unit with multiple electrical connectors. Identify the module by tracing the wiring harness from the ignition coils back to the control unit. The module will have 2 large multi-pin connectors.
4. 4

   Disconnect Electrical Connectors
   Locate the connector locking mechanisms on both electrical connectors attached to the ignition control module. Press down or slide the red safety locks to the unlock position. Press the release tabs on each connector while pulling the connector straight away from the module. Do not twist or rock the connectors during removal. If connectors are difficult to remove, verify the safety lock and release tab are fully disengaged before applying steady straight-out pressure; do not use solvents or force to free the connector.
5. 5

   Remove Module Mounting Hardware
   Remove the mounting bolts securing the ignition control module to its bracket. The module is typically secured with 3 mounting bolts using Torx fasteners. Use the appropriate Torx driver to remove each bolt completely. Note the locations of any ground straps or additional wiring that may be secured under the mounting bolts. Keep all hardware organized for reinstallation.
6. 6

   Remove Ignition Control Module
   Carefully lift the ignition control module away from its mounting location. If the module is adhered with thermal compound, gently rock it side to side to break the seal. Inspect the mounting surface and heat sink interface for any remaining thermal compound or debris. Note the orientation and positioning of the module for correct installation of the replacement unit.
7. 7

   Prepare Mounting Surface
   Clean the mounting surface and heat sink area thoroughly using a lint-free cloth and electrical contact cleaner. Remove all old thermal compound from both the mounting surface and the module bracket using a plastic scraper if necessary. The surfaces must be clean and free of debris to ensure proper heat dissipation for the new module. Wipe the area dry and allow any remaining cleaner to evaporate completely.
8. 8

   Apply Thermal Compound
   Apply a thin, even layer of Mercedes-Benz approved thermal compound to the heat sink contact area on the back of the new ignition control module. Use only enough compound to create a continuous film approximately 0.5mm thick. Excess compound can interfere with proper mounting and heat transfer. Ensure the compound covers the entire contact surface but does not extend beyond the edges where it could contaminate electrical connections.
9. 9

   Install New Ignition Control Module
   Position the new ignition control module in the mounting location, ensuring it is oriented correctly to match the original installation position. Align the mounting holes with the bracket. Press the module firmly against the mounting surface to seat the thermal compound properly. Start all mounting bolts by hand to ensure proper thread engagement before tightening.
10. 10

    Torque Mounting Bolts
    Using a torque wrench, tighten the mounting bolts to 31.0 Nm (23.0 lb-ft) in a cross pattern to ensure even pressure distribution. Tighten each bolt partially in sequence, then make a second pass to bring all bolts to final torque specification. This prevents warping of the module housing and ensures optimal heat sink contact.
11. 11

    Reconnect Electrical Connectors
    Inspect the electrical connectors for any signs of corrosion, damage, or bent pins. If connectors appear clean and undamaged, apply a small amount of dielectric grease to the contact pins to prevent corrosion. Align each connector with its corresponding port on the ignition control module and press firmly until you hear and feel a positive click. Slide or press the red safety locks back to the locked position. Gently tug on each connector to verify it is fully seated and locked.
12. 12

    Reinstall Air Intake Components
    Reinstall the lower air filter housing by aligning the mounting tabs and pressing down until they lock into place. Install the air filter element into the housing. Replace the air filter housing cover and secure the spring clips on both sides. Reconnect the air intake duct to the throttle body and tighten the hose clamp securely. Reattach any wiring harness clips along the intake duct to secure the harness in its original routing.
13. 13

    Reinstall Engine Cover
    Position the engine cover over the engine bay, aligning the rubber grommets on the underside of the cover with the mounting posts on the engine. Press down firmly on each corner and the center of the cover until all grommets are fully seated on their posts. Verify the cover is secure by attempting to lift each corner slightly.
14. 14

    Reconnect Battery and Initialize System
    Reconnect the battery negative terminal and tighten the terminal clamp securely. Turn the ignition to the ON position (without starting the engine) and wait for 30 seconds to allow the engine control unit to initialize and communicate with the new ignition control module. Check the instrument cluster for any warning lights related to the ignition system. If a check engine light is present, it may need to be cleared after verifying proper operation.

Reassembly

1. All components removed during this procedure are reinstalled in reverse order of removal
2. Ensure all electrical connectors are fully seated and safety locks are engaged
3. Verify all wiring harnesses are routed correctly and secured with original clips
4. Double-check that all fasteners are tightened to specification

Verification

• With the ignition in the ON position, verify that the check engine light illuminates briefly during the bulb check and then extinguishes
• Start the engine and listen for smooth idle with no misfires or hesitation
• Rev the engine gently to 2000-3000 RPM and verify smooth acceleration with no stumbling or misfiring
• Use a diagnostic scan tool to verify no ignition-related fault codes are present
• Test drive the vehicle under various load conditions to confirm proper ignition system operation
• After test drive, recheck all electrical connections and mounting bolts for tightness

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