Message Name:

AFT EQUIPMENT COMPARTMENT LIGHT NOT GO OFF

All the Lights in a Service Compartment do not come ON, or all the Lights in a Service Compartment do not go OFF.

• Left Auto Shut-off Box (A186)
• Auto Shut-off Box (A189)
• Light Switch
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Auto shutoff box A186 is used for the nose wheel compartment and avionics compartment lights. Auto shutoff box A189 is used for aft equipment-compartment and APU compartment lights.

1. Set a different service light switch to ON.
   NOTE: This makes sure the switch is not the cause of the problem.

   1. If fault remains, repair or replace the defective switch as required and do close out.
   2. If system checks are good, continue with next step.

2. Perform a continuity check for the ground discrete input circuit (light switch circuit) as follows:

   From	To	Switch Position	Result
   A186P1-C	Ground	ON
   A189P1-C	Ground	ON

   1. If there is continuity, repair defective wiring as required and do close out.
   2. If there is no continuity, continue with next step.

3. Perform a continuity check for the output voltage at the connectors as follows:

   From	To	Result
   A186P1-E	Ground
   A189P1-E	Ground

   1. If there is continuity, repair defective wiring as required and do close out.
   2. If there is no continuity, continue with next step.

4. Perform a continuity check between auto shutoff box as follows:

   From	To	Result
   A186P1-A	A186P1-B
   A189P1-A	A189P1-B

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

5. Replace the unserviceable Auto Shutoff Box.
6. Do close out.