Message Name:

WASTE TANK QTY READINGS ERRATIC OR SENSOR FAIL MESSAGE ON GALLEY TOUCH SCREEN

Waste Disposal Tank quantity level reading is erratic and/or SENSOR FAIL message is displayed on Galley Touch Screen Equipment (GTSE).

• Differential Pressure (DP) Sensor (MT550)
• Logic Control Module (LCM) (A800)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW700-38-0625 - Waste Tank Level DP Sensor - Fail message

Forum Articles/Infoservice/Newsletter:

• SB 700-38-5002 - Addition of heater and insulation blanket to the DP sensor of the water tank assembly
• SB 700-38-6002 - Addition of heater and insulation blanket to the DP sensor of the water tank assembly

1. Review the content of AW700-38-0625 and perform the recommended actions. Is the fault still present?

   1. If NO, do close out.
   2. If YES, continue with next step.

2. Perform a wiring check between the Waste Tank DP sensor and the Logic Control Module (LCM) as follows:

   From	To	Result
   MT550P1-A	A800P1-6
   MT550P1-D	A800P1-9
   MT550P1-B	A800P1-7
   MT550P1-C	A800P1-8

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.

3. Replace the DP sensor. Is the fault still present?

   1. If NO, do close out.
   2. If YES, continue with next step.

4. Replace the LCM.
5. Do close out.