Service manual

G420F(FE) Service Manual Chapter 9. Advanced Diagnostics 294
Table 2. Diagnostic Fault Codes (Flash Codes) cont’d.
DFC PROBABLE FAULT FAULT ACTION *
CORRECTIVE ACTION,
FIRST CHECK
381
(38)
IATRangeHigh
Intake Air Temperature
Sensor Input is High normally
set if the IAT temperature
sensor wire has been
disconnected or the circuit
has opened to the SECM.
TurnOnMil
Check TMAP connector and IAT signal
wiring for a shorted circuit
TMAP Pin 2 to SECM Pin B12 (signal)
TMAP Pin 1 to SECM Pin B1 (sensor
GND)
To check the IAT sensor of the TMAP
disconnect the TMAP connector and
measure the IAT resistance Resistance
is approx 2400 ohms at room
temperature.
391
IAT_IR_Fault
Intake Air Temperature not
changing as expected
None
Check connections to TMAP sensor.
Check that TMAP sensor is properly
mounted to manifold.
421
EST1_Open EST1
output open, possibly open
EST1 signal or defective
spark module
TurnOnMil
Check coil driver wiring and connector
for open circuit
SECM Pin A9 (EST1) to OEM ignition
system. See application note.
Verify GND on ignition module Pin A
(of both connectors)
Verify +12 Vdc on ignition module Pin
B (of both connectors)
Refer to application manual for specific
engine details
422
EST2_Open EST2
output open, possibly open
EST2 signal or defective
spark module
TurnOnMil
Check coil driver wiring and connector
for open circuit SECM Pin A10 (EST2)
to OEM ignition system.
See application note. Verify GND on
ignition module Pin A (of both
connectors)
Verify +12 Vdc on ignition module Pin
B (of both connectors)
Refer to application manual for specific
engine details.
423
EST3_Open EST3
output open, possibly open
EST3 signal or defective
spark module
TurnOnMi
Check coil driver wiring and connector
for open circuit
SECM Pin A3 (EST3) to OEM ignition
system. See application note.
Verify GND on ignition module Pin A
(of both connectors)
Verify +12 Vdc on ignition module Pin
B (of both connectors)
Refer to application manual for specific
engine details.
(*) Fault actions shown are default values specified by the OEM.