STEP/SEQUENCE
RESULT
WHAT TO DO NEXT
TM 9-2320-363-20-1
Section 4
TROUBLESHOOTING CHARTS
E. FLASH CODE: 28
J1587 CODE:
P172 4 - AIR TEMPERATURE CIRCUIT FAILED LOW (LOW VOLTAGE)
28-5
Check ECM
Connectors
Check terminals at the ECM
Terminals and
Reprogram ECM. Then go to
engine harness connector
connectors are okay
28-30.
(both the ECM and harness side)
for damage; bent, corroded, and
Problem found.
Repair terminals/connectors.
unseated pins or sockets.
Then go to 28-30.
Especially N2 and Y2 of the
ECM connector
28-30
Verify Repairs
Turn ignition off.
(No codes).
Repairs are complete.
Reconnect all connectors.
Turn ignition on.
Code 172/4 (and
All system diagnostics are
Clear codes.
any other codes)
complete. Please review this
Note status of "Check Engine"
section from the start to find
light.
the error.
If "Check Engine" light does not
stay on, start engine and run until
Any other codes
Go to START-1, pg 3-345.41,
"Check Engine" light comes on
except Code 172/4.
to service other codes.
or 8 minute. Stop engine.
Read inactive codes
Change 3 3-345.265
