GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Firebird 🢒 DTC 🢒 DTC C0239

Circuit Description

Spark Retard is simultaneously controlled by the EBCM and the PCM. The PCM supplies a 12 volt pull up voltage. This voltage is monitored by the PCM, the EBCM requests spark retard by pulling the voltage low.

Conditions for Setting the DTC

DTC C0239 can be set anytime when the EBCM senses a short to ground, a short to battery voltage , or an open in spark retard control signal circuit.

Action Taken When the DTC Sets
    • A malfunction DTC is stored.
    • The ABS/TCS is disabled.
    • The Red BRAKE Warning indicator turn on.

Conditions for Clearing the DTC
    • Condition for DTC is no longer present and scan tool clear DTC function is used.
    • 100 ignition cycles have passed with no DTCs detected.

Diagnostic Aids
    • It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
    • If an intermittent malfunction exists refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks for the pull up voltage from the PCM.

    2.

  2. This step checks for a short to voltage.

    3.

  3. This step checks for a short to ground.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the EBCM connector C1.
  3. Install the J 39700 Universal Pinout Box using the J 39700-530 Cable Adapter to the EBCM harness connector C1 only.
  4. Turn the ignition switch to the RUN position, engine off.
  5. Using DMM, measure the voltage at terminal 19 of J 39700 .

Is the voltage within the range specified in the value(s) column?

B+

Go to Step 3

Go to Step 6

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the PCM connector C2.
  3. Turn the ignition switch to the RUN position, engine off.
  4. Using DMM, measure the voltage at terminal 19 of J 39700 .

Is the voltage within the range specified in the value(s) column?

Above 1V

Go to Step 4

Go to Step 5

4

Repair spark retard control signal circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 11

--

5

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

Is the replacement complete?

--

Go to Step 11

--

6

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the PCM connector C2.
  3. Using DMM, measure the resistance between terminals 19 and 15 of J 39700 .

Is the resistance within the range specified in the value(s) column?

OL

Go to Step 8

Go to Step 7

7

Repair spark retard control circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 11

--

8

Using DMM, measure the resistance between terminal 19 of J 39700 and spark retard control circuit of the PCM connector C2.

Is the resistance within the range specified in the value(s) column?

0-5ohms

Go to Step 10

Go to Step 9

9

Repair spark retard control circuit for an open. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 11

--

10

Suspect the PCM. Refer to Diagnostic System Check - Engine Controls in Engine Controls.

Is the repair complete?

--

Go to Step 11

--

11
  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 the DTC reset?

--

Go to Step 2

System OK