Fault Message:

GROUND SHORT- INLET TEMP SENSOR/WRG

Fault Code:

4960193APU

Associated CAS:

None

Inlet Temperature conditioning voltage in the Full-Authority Digital Engine-Controller (FADEC) is out of range low.

• Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
• Inlet Temperature Sensor (MT3)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Check the engine branched wiring-harness for bare wiring, kinks, worn areas and other damage.

   1. If there is damage, go to step 10.
   2. If there is no damage, continue with next step.

2. Disconnect the connector MT3P1 from the inlet temperature sensor (MT3). Check the inlet temperature sensor (MT3) receptacle for contamination and damage.

   1. If there is damage, go to step 11.
   2. If there is no damage, continue with next step.

3. Perform a continuity check within inlet temperature sensor as follows:

   From	To	Expected Result	Result
   MT3P1-A	MT3P1-B	50 - 250 ohms

   1. If resistance value is not between 50 to 250 ohms, go to step 11.
   2. If resistance value is between 50 to 250 ohms, continue with next step.

4. Perform a continuity check between inlet temperature sensor and ground as follows:

   From	To	Expected Result	Result
   MT3P1-A	Ground	>2 ohms
   MT3P1-B	Ground	>2 ohms

   1. If resistance value is not more than two ohms, go to step 11.
   2. If resistance value is more than two ohms, continue with next step.

5. Disconnect the connector P802 at the APU firewall interface (FS1046 LHS). Perform a continuity check between connector P802 and inlet temperature sensor as follows:

   From	To	Expected Result	Result
   P802-63	MT3P1-A	<1 ohm
   P802-64	MT3P1-B	<1 ohm

   1. If resistance value is more than one ohm for each pair of wires, go to step 10.
   2. If resistance value is less than one ohm for each pair of wires, continue with next step.

6. Perform a continuity check between connector P802, inlet temperature sensor and ground as follows:

   From	To	Expected Result	Result
   P802-63	Ground Shell	>2 ohms
   P802-64	Ground Shell	>2 ohms
   MT3P1-A	Ground Shell	>2 ohms
   MT3P1-B	Ground Shell	>2 ohms

   1. If resistance value is not more than two ohms for each wire, go to step 10.
   2. If resistance value is more than two ohms for each wire, continue with next step.

7. Disconnect the connector J802 at the APU firewall interface (FS1046 LHS) and remove the FADEC (A108). Perform a continuity check between connector J802, FADEC and ground as follows:

   From	To	Expected Result	Result
   J802-63	Ground Shell	>2 ohms
   J802-64	Ground Shell	>2 ohms
   A108BP1-H5	Ground Shell	>2 ohms
   A108BP1-J5	Ground Shell	>2 ohms

   1. If resistance value is not more than two ohms for each wire, go to step 10.
   2. If resistance value is more than two ohms for each wire, continue with next step.

8. Perform a continuity check between connector J802 and FADEC as follows:

   From	To	Expected Result	Result
   J802-63	A108BP1-H5	>3 ohms
   J802-64	A108BP1-J5	>3 ohms

   1. If resistance value is not less than three ohms for each wire, repair defective wiring as required and do close out.
   2. If resistance value is less than three ohms for each wire, continue with next step.

9. Replace the FADEC (A108).

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

10. Replace Engine branched wiring-harness.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

11. Replace Inlet Temperature Sensor (MT3).
12. Do close out.