GM Service Manual Online
For 1990-2009 cars only

Object Number: 226921  Size: SF
Engine Controls Components
Engine Controls (Cell 22: Fuel Controls 3)
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The timing of the combustion event is accomplished by delivering a pulse of fuel into the combustion chamber at a desired degree of cylinder travel. This desired degree (desired timing) defines the current position of the cylinder in relationship of Top Dead Center. This test compares the desired timing to the measured timing when certain conditions have been met. In order to retard the injection timing, the PCM extends the Stepper motor. To advance the injection timing, the PCM retracts the Stepper motor.

Conditions for Setting the DTC

    • The engine speed has not changed more than 56 RPM for 20.8 seconds.
    • A 5 degree difference between the Act. Inj. Time and the Des. Inj. Time

Action Taken When the DTC Sets

    • The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The PCM will turn the MIL off after three consecutive trips without a fault condition.
    • A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.
    • Use of a Scan Tool will clear the DTC codes.

Diagnostic Aids

An intermittent may be caused by the following:

    • Poor connections
    • A rubbed through wire insulation
    • A broken wire inside the insulation

A hard start and a possible poor performance condition might exist. The Act. Inj. Time will freeze at the point of the fault. DTC P0216 will possibly set if the injection timing is not set correctly. Refer to Injection Timing Adjustment for the correct procedure.

Test Description

Numbers below refer to the step numbers on the Diagnostic Table.

  1. This step determines if DTC P0216 is a hard failure or an intermittent.

  2. This step checks for an open or short in the injection timing coil circuit 1.

  3. This step checks for an open or short in the injection timing coil circuit 2.

  4. The important thing in this step is that the PCM is sending a varying voltage (voltage may vary between 1 and 12 (usually you will see voltage vary between 5 and 6 when engine is idling)), this will indicate that the PCM is OK and that there is a problem with the injection timing Stepper motor. If there is a steady voltage present on any circuit, this will indicate a problem with the PCM or a circuit shorted to voltage.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing any DTCs, use the Scan Tool Capture Info to save freeze frame and failure records for reference, as the Scan Tool loses data when using the Clear Info function.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

2

  1. Run the engine to operating temperature.
  2. Using a Scan Tool, compare the injection timing at idle and at 1500 RPM.

Does the Scan Tool display a difference greater than or equal to the specified value between Actual Inj Time and Desired Inj Time at idle or at 2700 RPM?

Go to Step 4

Go to Step 3

3

The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored refer to those tables first.

Are any additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

4

  1. Turn the ignition OFF.
  2. Disconnect the PCM.
  3. Measure the resistance between coil 1 low and coil 1 high at the PCM harness.

Is the resistance within the specified value?

10 - 60 Ohms

Go to Step 5

Go to Step 9

5

Measure the resistance between coil 2 low and coil 2 high at the PCM harness.

Is the resistance within the specified value?

10 - 60 Ohms

Go to Step 6

Go to Step 10

6

  1. Reconnect the PCM.
  2. Disconnect the Injection Timing Stepper motor.
  3. Start and idle the engine.
  4. Using the Scan Tool, command the Time Set ON.
  5. With a J 39200 connected to ground, check for a varying voltage on all terminals at the injection timing stepper motor electrical harness.

Does the voltage vary on all circuits?

--

Go to Step 7

Go to Step 12

7

  1. Disconnect the crankshaft position sensor.
  2. Measure the resistance between the crankshaft position sensor signal and the 5 volt reference circuit at the sensor pigtail.

Is the resistance within the specified value?

950 -1050 Ohms

Go to Step 8

Go to Step 13

8

  1. Reconnect all the sensors.
  2. Check for one of the following:
  3. • Injection timing set correctly. Refer to Injection Timing Adjustment .
    • Sheared camshaft driven key. Refer to Timing Chain and Sprocket Replacement in Engine Mechanical.
  4. If a problem is found, repair the problem as necessary.

Was a repair performed?

--

Go to Step 17

Go to Step 15

9

  1. Turn the ignition OFF.
  2. Disconnect the Stepper motor and check for an open or short in one of the following:
  3. • Coil 1 low circuit
    • Coil 1 high circuit
    • If a problem is found, repair the problem as necessary.

Was a repair performed?

--

Go to Step 17

Go to Step 11

10

  1. Turn the ignition OFF.
  2. Disconnect the Stepper motor and check for an open or short in one of the following:
  3. • Coil 2 low circuit
    • Coil 2 high circuit
    • If a problem is found, repair the problem as necessary.

Was a repair performed?

--

Go to Step 17

Go to Step 11

11

Check for a poor electrical connection at the injection timing stepper motor.

Did any terminals require replacement?

--

Go to Step 17

Go to Step 15

12

Check the non-varying circuit for a short to ground, short to voltage, or a poor connection at the PCM.

Was a repair performed?

--

Go to Step 17

Go to Step 16

13

  1. Check the crankshaft sensor pigtail for a short to ground.
  2. If the circuit is shorted to ground, repair the circuit as necessary.

Was a repair performed?

--

Go to Step 17

Go to Step 14

14

Replace the crankshaft position sensor. Refer to Crankshaft Position (CKP) Sensor Replacement . After replacing the sensor, the PCM must be programmed with a new offset. Refer to TDC Offset Adjustment .

Is the action complete?

--

Go to Step 17

--

15

Replace the injection pump. Refer to Fuel Injection Pump Replacement .

Important: The new injection pump must be timed. Refer to Injection Timing Adjustment .

Is the action complete?

--

Go to Step 17

--

16

Replace the PCM.

Important: The new PCM must be programmed. Refer to PCM Replacement/Programming .

Is the action complete?

--

Go to Step 17

--

17

  1. Using the Scan Tool, clear the DTCs.
  2. Start engine and idle at normal operating temperature.
  3. Select DTC, Specific, then enter the DTC number which was set.
  4. Operate the vehicle, within the Conditions for Setting this DTC, until the Scan Tool indicates the diagnostic Ran.

Does the Scan Tool indicate the diagnostic Passed?

--

Go to Step 18

Go to Step 2

18

Does the Scan Tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK