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For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2001 🢒 Isuzu T-Series (Truck Line C) 🢒 Engine 🢒 Engine Controls - 7.8L 🢒 DTC 0274

Circuit Description

A hydraulic piston and a two-way valve (TWV) solenoid valve have been added to the conventional nozzle. When receiving signals from the engine control module (ECM), the TWV opens and closes to change the pressure in the pressure adjustment chamber on top of the hydraulic piston in order for the hydraulic piston to inject the fuel from the nozzle. If the TWV coil or harness is disconnected from the number 4 cylinder, DTC 0274 will set.

Conditions for Setting the DTC

The TWV coil or harness is disconnected and the battery voltage is over 10 volts, except when measured on overrun.

Action Taken When the DTC Sets
    • The engine control module (ECM) will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected.
    • The injection amount is limited to a maximum of 80 mm³/seconds and the boost is 0.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

DTC 0274 can be cleared by using the Clear Info option on the Tech 2 or by using the Diag Clear Switch.

Diagnostic Aids

Inspect for the following conditions:

    • Poor connections at the ECM
        Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections.
    • Erratic RPM
    • Lack of engine power

DTC 0274 (Cylinder No. 4) TWV Side Disconnected

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Is DTC 0274 set with the ignition ON or with the engine operating?

--

Go to Step 2

Go to Diagnostic Aids

2
  1. Turn the ignition OFF.
  2. Disconnect the TWV harness connector from the ECM.
  3. Measure the resistance between pin number 87, 96 and pin number 119 at the ECM connector of the TWV harness.

Does the resistance measure within the specified range?

0.9-1.3 ohms

Go to Step 7

Go to Step 3

3
  1. Turn the ignition OFF.
  2. Disconnect the TWV harness connector from the ECM and the TWV on the cylinder head.
  3. Measure the resistance on the TWV harness between pin number 87, 96 on the ECM and pin number 5, 6 on the TWV.

Does the resistance measure below the specified value?

2 ohms

Go to Step 4

Go to Engine Coolant Temperature Sensor Replacement

4

Measure the resistance at the TWV connector between pin number 5, 6 and 3, 4 at connector 2 for TWV 4.

Does the resistance measure within the specified range?

0.4-0.8 ohms

Go to Step 6

Go to Step 5

5
  1. Remove the cylinder head cover.
  2. Inspect the upper portion of the cylinder head.
  3. Repair the condition as necessary. Refer to Cylinder Head Replacement in Engine Mechanical.

Did you find and correct the condition?

--

Go to Step 6

--

6
  1. Connect all connectors and terminals on the TWV harness.
  2. Install the cylinder head cover.
  3. Turn the ignition ON.

Did the DTC set?

--

Go to Engine Control Module Replacement/Restore Fuel Rate Data

Go to Step 7

7
  1. Clear the DTCs.
  2. Turn the ignition ON.

Did the DTC set?

--

Go to Step 2

System OK