GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2003 🢒 Ascender - 2WD 🢒 DTC 🢒 DTC C0298 or P1571

Circuit Description

C0298

The powertrain control module (PCM) sends a state of health message to the EBCM via class 2 serial data communications.

P1571

The EBCM requests desired engine torque from the PCM via the requested torque signal circuit.

Conditions for Running the DTC

C0298

The ignition is ON.

P1571

    • The ignition is ON.
    • The engine is running at a speed greater than 500 RPM for 5-20 seconds.
    • The EBCM has not set any current TCS related DTCs.

Conditions for Setting the DTC

C0298

The EBCM receives a state of health message informing the EBCM that the PCM has lost the ability to perform traction control.

P1571

The PCM receives an invalid requested torque signal for 3 seconds.

Action Taken When the DTC Sets

C0298

If equipped, the following actions occur:

    • The EBCM disables the TCS.
    • The TRACTION OFF indicator turns ON.

P1571

    • The PCM sends a state of health message to the EBCM informing the EBCM that the PCM has lost the ability to perform traction control.
    •  The EBCM sets DTC C0298 as a current DTC for as long as the malfunction is present.

Conditions for Clearing the DTC

C0298

The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

P1571

    • The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
    • A history DTC clears automatically after 40 consecutive warm-up cycles without a PCM detected failure.

Diagnostic Aids

C0298

A requested torque signal malfunction is only one possible cause for the PCM to lose the ability to perform traction control. DTC C0298 may set due to engine overheating, loss of ignition timing control by the PCM, etc. If DTC P1571 is not set, refer to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.2L in order to identify other possible causes of DTC C0298.

P1571

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs and Wiring Repairs in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. This step tests for voltage supplied to the EBCM from the PCM.

    2.

  2. This step verifies the EBCM is creating a requested torque signal with a valid Hz frequency.

    3.

  3. This step verifies the EBCM is creating a requested torque signal with a valid duty cycle.

    4.

  4. The EBCM may be damaged if the requested torque signal circuit is shorted to voltage.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics in Engine Controls - 4.2 L

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

Is DTC P1571 set?

--

Go to Step 3

Go to Diagnostic Aids

3
  1. Use a scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
  3. Does DTC P1571 set?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect from the EBCM, the harness connector containing the requested torque signal circuit.
  3. Turn ON the ignition.
  4. Use a DMM in order to measure the voltage between the requested torque signal circuit and a good ground.

Does the voltage measure within the specified range?

4.75-5.25 V

Go to Step 5

Go to Step 7

5

  1. Turn OFF the ignition.
  2. Install a J 39700 universal breakout box and a J 39700-325 adapter cable. Install the equipment between the EBCM and the EBCM harness connector.
  3. Start the engine.
  4. Use the DMM in order to measure the Hz frequency of the requested torque signal.

Does the Hz frequency of the requested torque signal measure within the specified range?

121-134 Hz

Go to Step 6

Go to Step 9

6

Use the DMM in order to measure the duty cycle of the requested torque signal circuit.

Does the duty cycle of the requested torque signal measure within the specified range?

40-95%

Go to Step 8

Go to Step 9

7

Test the requested torque signal circuit for an open, a short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 8

8

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Important: Perform the set up procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.2 L.

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Important: Use the scan tool in order to perform the Tire Size Calibration procedure.

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does DTC P1571 reset?

--

Go to Step 4

System OK