2004 ISUZU TF SERIES Workshop Manual

Page 1697 of 4264

ISUZU TF SERIES 2004  Workshop Manual 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–325
Diagnostic Trouble Code (DTC) P1612 (Symptom Code A) (Flash Code 56) 
Immobilizer No or Wrong Signal
Step Action Value(s) Yes No
1Was the “On-Boa

Page 1698 of 4264

ISUZU TF SERIES 2004  Workshop Manual 6E–326 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6 Using the DVM and check the “CHECK ENGINE”
lamp circuit.
1.  Ignition “Off”, engine “Off”. 
2. Disconnect the meter connector and imm

Page 1699 of 4264

ISUZU TF SERIES 2004  Workshop Manual 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–327
7 Using the DVM and check the “CHECK ENGINE”
lamp circuit.
Breaker box is available: 
1. Ignition “Off”, engine “Off”. 
2. Install the

Page 1700 of 4264

ISUZU TF SERIES 2004  Workshop Manual 6E–328 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 Using the DVM and check the ECM and immobilizer
control unit communication circuit.
1. Ignition “Off”, engine “Off”. 
2. Disconnect the i

Page 1701 of 4264

ISUZU TF SERIES 2004  Workshop Manual 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–329
10 Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming S

Page 1702 of 4264

ISUZU TF SERIES 2004  Workshop Manual 6E–330 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1613 (SYMPTOM CODE A) 
(FLASH CODE 56) IMMOBILIZER NO OR WRONG SIGNAL
Condition for setting the DTC and action taken

Page 1703 of 4264

ISUZU TF SERIES 2004  Workshop Manual 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–331
Diagnostic Trouble Code (DTC) P1613 (Symptom Code A) (Flash Code 56) 
Immobilizer No or Wrong Signal
Step Action Value(s) Yes No
1Was the “On-Boa

Page 1704 of 4264

ISUZU TF SERIES 2004  Workshop Manual 6E–332 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6 Using the DVM and check the “CHECK ENGINE”
lamp circuit.
1. Ignition “Off”, engine “Off”. 
2. Disconnect the meter connector and immo