Failure of the PHC 3

TASK 30-31-00-810-864-A
Failure of the PHC 3

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 303103
AMM 30-31-34-000-002	Removal of the Probe Heat Computer (PHC)
AMM 30-31-34-400-002	Installation of the Probe Heat Computer (PHC)
AMM 34-12-34-000-001	Removal of the ADIRU
AMM 34-12-34-400-001	Installation of the ADIRU
ASM 341302

3. Fault Confirmation
Subtask 30-31-00-860-055-A

A. Test
(1) If the fault occurs at each engine start or each engine shutdown:

(2) If the fault occurs in other conditions:

4. Fault Isolation
Subtask 30-31-00-810-116-A

A. Do the steps that follow:

Subtask 30-31-00-810-140-A

B. Do the steps that follow:

ASM 341302.
(1) If the wiring is not correct:

(2) If the wiring is correct:

(a) If there is a ground signal:

(b) If there is no ground signal:

Connect electrical connector A to PHC3.
Replace the RELAY-OIL LOW PRESS AND GROUND, ENG 1 [12KS1] and the RELAY-OIL LOW PRESS AND GROUND, ENG 2 [12KS2] .

1 If the fault continues:

Disconnect electrical connector A from PHC3.
Do a check and repair the wiring from:
The PHC3 (6DA3) pin A/f to the engine 1 oil low pressure and ground relay (12KS1) pin A/2
The engine 1 oil low pressure and ground relay (12KS1) pin A/A to the ground
The PHC3 (6DA3) pin A/g to the engine 2 oil low pressure and ground relay (12KS2) pin A/2, and
The engine 2 oil low pressure and ground relay (12KS2) pin A/A to the ground.

[Rev.8 from Aug 2018] 2026.04.04 04:29:39 UTC