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For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2001 🢒 Isuzu T-Series (Truck Line C) 🢒 Engine 🢒 Engine Controls - 7.8L 🢒 Diagnostic Indication - Engine Controls

Retrieving Diagnostic Trouble Codes (DTC)

Vehicle Type T6500, T7500, and T8500
Object Number: 777688 Size: SH
(1)Off-White Diagnostic Connector
(2)Blue Memory Clear Connector

Vehicle Type T5500
Object Number: 735668 Size: SH
(1)Engine Control Module (ECM) Harness Connector
(2)ECM mounting bracket
(3)White Diagnostic Connector
(4)Blue memory clear connector
(5)Right Seat Stand

There are 3 diagnostic modes for the malfunction indicator lamp (MIL). The mode will depend on which diagnostic connector is grounded. Refer to the above figures for the appropriate location and connector. The diagnostic modes are as follows:

Control

MIL Status

Condition

User Mode

ON

All diagnostic Connectors open

Dealer Mode 1

DTC indication of current trouble only
    • Off-White diagnostic connector grounded
    • No engine stall
    • For 1 second or more

Dealer Mode 2

DTC indication of current and past troubles
    • White diagnostic connector grounded
    • Engine stall
    • For 1 second or more

Diagnostic Malfunction Indicator Lamp (MIL) Patterns in User Mode
    • In pattern 1 the MIL is illuminated all of the time.
    • In pattern 2 the MIL illuminates after 20 seconds of continuous engine speed below 700 RPM.
    • In pattern 3 the MIL is not illuminated.

Diagnostic Code Output in the Dealer Modes

The dealer modes are used to retrieve flash DTCs from the engine control module (ECM) through the MIL. The following is the format used to read the DTCs with the MIL.

    • DTCs will flash on the MIL after 2.4 seconds of the MIL being OFF with the dealer mode enabled.
    • The number of MIL flashes corresponds to a digit in the DTC.
    • The DTC will flash starting with the highest numbered DTC.
    • If multiple self-diagnosis codes are indicated, the each code is flashed 3 times, then flash the next code.
    • When there is no DTC output, DTC 001 or 01 is set as the normal system DTC.
    • The MIL flashing is stopped when the diagnostic connector is ungrounded.

Important: The tolerance of difference between light ON and light OUT time is +0.3 to -0.1 seconds.

Item

Light on time (Sec.)

Light out time (Sec.)

Figure of 100

0.3

0.6

Figure of 10

1.2

0.6

Figure of 1

0.3

0.6

Code intervals

0.0

2.4

Clearing Diagnostic Trouble Codes (DTC)

Vehicle Type T6500, T7500, and T8500
Object Number: 777688 Size: SH
(1)Off-White Diagnostic Connector
(2)Blue Memory Clear Connector

Vehicle Type T5500
Object Number: 735668 Size: SH
(1)Engine Control Module (ECM) Harness Connector
(2)ECM mounting bracket
(3)White Diagnostic Connector
(4)Blue memory clear connector
(5)Right Seat Stand

Use the following procedure to clear the diagnostic codes. Refer to the above figures for the appropriate location and connector.

  1. Ground the memory clear connector for 1 second or more.
  2. Remove the ground from the memory clear connector for 1 second or more.
  3. Ground the memory clear connector for 1 second or more.