Updated Case Study Drive Train Mobility Warning on BMW M5 with S63 Engine

Customer Complaint:
The customer reported a “Drive Train Mobility” warning message displayed on the control system, accompanied by the Check Engine Light.

Vehicle Details:

• Make: BMW
• Model: M5
• Engine: S63
• Model Year: Post-2013

Diagnostic Process:

1. Initial Scan Tool Analysis:

   • Retrieved fault codes:
     • 20A611: Coolant Pump Turbocharger Feedback Line: Short Circuit (Permanent).
     • 20A504: Turbocharger Coolant Pump Actuation: Line Disconnection.

2. Wiring and Power Supply Inspection:

   • Checked wiring connections to the turbocharger coolant pump for wear and continuity.
   • Verified the ground connection, power supply, and signal circuits.

3. Power Supply Path Assessment (Model-Specific):

   • Post-2013 Models: The turbocharger coolant pump power is supplied directly via a fuse.
   • Pre-2013 Models: Power is managed directly by the DME (Digital Motor Electronics).

4. Advanced Diagnostics:

   • Confirmed that the power circuit to the turbocharger coolant pump was intact, but the pump was not receiving ground and signal power.
   • Further testing revealed a broken wire between the DME and the coolant pump.

Resolution:

1. Wiring Repair:

   • Located the break in the wire between the DME and the turbocharger coolant pump.
   • Repaired and secured the damaged wire to restore the connection.

2. System Testing:

   • Verified the integrity of the wiring and ensured proper ground and signal power delivery to the coolant pump.
   • Cleared fault codes and performed an operational test.

3. Functional Test:

   • Started and ran the engine for an extended period.
   • Observed the turbocharger coolant pump, which began operating correctly after the engine warmed up and sufficient demand was met.

Outcome:
The repair successfully resolved the issue, eliminating the “Drive Train Mobility” warning and Check Engine Light. The turbocharger coolant pump operated as intended, and the vehicle was returned to the customer in optimal working condition.

Key Takeaways:

• Thorough understanding of model-specific power supply paths (e.g., DME-controlled vs. direct fuse supply) is crucial for accurate diagnostics.
• Inspecting and repairing damaged wiring is often a cost-effective solution compared to component replacement.
• Proper engine testing ensures the reliability of the repair and system functionality.

Service Provided By:
Giz Tech Automotive
Your trusted automotive repair specialist in Manukau.