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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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12/26/25

Message Overview:

Message Name:

TR ICU 7

Message Code:

B3-304254

Reporting LRU: Left Engine Thrust Reverser Isolation Control-Unit (L ENG TR ICU)
Associated CAS: None
System Description: 78-30-00 - Thrust Reverser
Schematic Diagram: SSM 78-30-00-101 - Thrust Reverser
Wiring Diagram: WM 78-32-07-1_001 - Sheet 1 - Thrust-Reverser Isolation Control-Unit (ICU) LHS - ALL

Message Description:

Left Engine Thrust Reverser Isolation Control-Unit (ICU) fault 7.

[MCID 1445]
Detection of 28 volts at the TR ICU solenoid when not expected.

Possible Causes:

  • Aircraft Wiring Harness
  • Aircraft Relays
  • Proximity Sensor Electronic Unit (PSEU) (A9)
  • Brake Control Unit (BCU) (A67)

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

Quick Links:

Operational Test of the Brake System AMM 32-43-00-710-801
Removal of the Brake Control Unit AMM 32-43-01-000-801
Installation of the Brake Control Unit AMM 32-43-01-400-801
Operational Test of the Proximity Sensors AMM 32-61-00-710-801
Removal of the Proximity-Sensor Electronic Unit (PSEU) AMM 32-61-09-000-801
Installation of the Proximity-Sensor Electronic Unit (PSEU) AMM 32-61-09-400-801
Removal of the Engine Electronic Control Unit (ECU) AMM 76-10-05-000-801
Installation of the Engine Electronic Control Unit (ECU) AMM 76-10-05-400-801
Deactivation of the Thrust Reverser (For Maintenance) AMM 78-30-00-040-801
Activation of the Thrust Reverser (For Maintenance) AMM 78-30-00-440-801
Operational Test of the Thrust Reverse AMM 78-30-00-710-801
General Visual Inspection of the Thrust Reverser AMM 78-30-00-210-802
Removal of the Thrust-Reverser Isolation Control-Unit (ICU) AMM 78-32-07-000-801
Installation of the Thrust-Reverser Isolation Control-Unit (ICU) AMM 78-32-07-400-801
General Visual Inspection of the Thrust-Reverser Wiring Harness AMM 78-33-00-210-801
Removal of the Thrust-Reverser Harness (Multiplexer) AMM 78-33-06-000-804
Installation of the Thrust-Reverser Harness (Multiplexer) AMM 78-33-06-400-804
Safety Precautions - Maintenance Practices - ALL SPM 20-00-01-02
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL SPM 20-20-00-02

Troubleshooting Recommendations:

  1. MCID 1445 fault present, troubleshoot using the following steps for aircraft and engine fault isolation with reference to the Light Engine Maintenance Manual Subtask 72-00-00-810-276-A01.
  2. Do close out.

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