GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Express (CNG) 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 DTC P1215

Circuit Description

The Alternative Fuels ECM contains electronic devices called output driver modules. The output driver modules provide switchable outputs, or control circuits, for operating solenoids, relays, telltales, and other devices. Each of the outputs has an internal fault line that the Alternative Fuels ECM can monitor for faulted circuit conditions.

Two types of outputs can be utilized. High side drivers supply voltage on the control circuit. Low side drivers supply a ground on the control circuit. Currently all monitored outputs are low side drivers. In order for the fault line to detect a failure, the state of the control circuit must be opposite of the expected state. If the Alternative Fuels ECM is commanding an output ON, then 0 volts should be monitored by the fault line. If the Alternative Fuels ECM is commanding an output OFF then the voltage supplied to the controlled device should be monitored by the fault line.

This DTC is used to indicate that the Alternative Fuels ECM fault line has monitored a control circuit fault.

Monitored control circuits include the following components:

    • The Fuel Control Solenoid (FCS) control circuit
    • The Idle Control Solenoid (ICS) control circuit
    • The Alternative Fuels Operation (AFO) Signal control circuit
    • The Low Pressure Lock-Off (LPL) solenoid control circuit
    • The EVAP Canister Purge Enable Control circuit

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The Alternative Fuels ECM monitors a control circuit fault for at least 1 second continuously.

Action Taken When the DTC Sets

    • The Alternative Fuels ECM will illuminate the MIL and store the DTC as History during 1 drive trip in which the diagnostic runs and fails.
    • The Alternative Fuels ECM will record operating conditions at the time the DTC sets. This information will be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

    • The Last Test Failed status will clear when the DTC runs and passes.
    • The Alternative Fuels ECM will turn OFF the MIL after 3 consecutive drive trips that the DTC runs and passes.
    • The History status will clear after 40 consecutive WARM-UP cycles with NO failures of ANY DTC.
    • All DTC Information can be cleared with a scan tool.

Diagnostic Aids

The scan tool Output Driver data parameters are only functional when the vehicle is operating on CNG.

Intermittent Condition

A fault not present indicates the condition that caused the DTC to set is intermittent and not currently present. Refer to the Intermittent Conditions diagnostic information located in Symptoms - Engine Controls. If any additional DTCs were stored proceed to the applicable DTC table in the order stated in Diagnostic System Check - Alternative Fuels (Engine Controls) .

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check - Alternative Fuels - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)

2
  1. Turn ON the ignition, with the engine OFF.
  2. Using the scan tool Alt. Fuel Engine Data selection, observe the Alternative Fuels Operation (AFO) Signal and the Alternative Fuels Operation (AFO) Signal Command displays.

Do both displays indicate the same information?

--

Go to Step 3

Go to Step 10

3
  1. Turn ON the ignition, with the engine OFF.
  2. Capture the DTC Information stored when this DTC set from the Alternative Fuels ECM into the scan tool.
  3. Clear the DTC Information from the Alternative Fuels ECM.
  4. Command the Alternative Fuel Operation (AFO) Signal circuit back and forth between PCM and AFECM using the scan tool Alt. Fuels Special Function.
  5. Observe the AFO Signal and the AFO Signal Command displays while commanding.

Do both displays indicate PCM during one commanded state and then both displays indicate AF ECM during the other commanded state?

--

Go to Step 4

Go to Step 11

4
  1. Exit the Special Function area of the scan tool.
  2. Start and idle the engine.
  3. Observe the Alternative Fuels Operation (AFO) Signal and the Alternative Fuels Operation (AFO) Command displays.

Is the engine operating on Alternative Fuel?

--

Go to Step 5

Go to Step 8

5

Observe the idle control solenoid (ICS) output circuit status scan tool data parameter while the engine is operating on CNG.

Does the data parameter indicate OK?

--

Go to Step 6

Go to Step 15

6

Observe the fuel control solenoid (FCS) output circuit status scan tool data parameter while the engine is operating on CNG.

Does the data parameter indicate OK?

--

Go to Step 7

Go to Step 19

7

Observe the EVAP purge reduce request output circuit status scan tool data parameter during both open loop and closed loop operation. Open loop operation occurs for several seconds after every ignition ON. Closed loop operation occurs after the engine is warm and has been operating for several seconds.

Does the data parameter indicate OK?

--

Go to Step 8

Go to Step 27

8
  1. Start and idle the engine.
  2. Listen for LPL operation as you command the LPL Open and Closed using the scan tool Alt. Fuels Special Function.

Does the LPL operate as commanded?

--

Go to Step 9

Go to Step 31

9

The fault is not present. Refer to Diagnostic Aids.

Are any DTCs stored that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Intermittent Conditions

10
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Alternative Fuels Operation (AFO) SIGNAL display.

Does the data parameter indicate the PCM is in control of engine fueling?

--

Go to Step 11

Go to Step 12

11
  1. Turn OFF the ignition.
  2. Disconnect the Alternative Fuels ECM connectors.
  3. Using a fused jumper, connect the Alternative Fuels ECM connector Alternative Fuels Operation (AFO) Command circuit terminal to a known good ground.

    4. If the jumper fuse opens, the AFO circuit is shorted to voltage.

  4. Turn ON the ignition, with the engine OFF.
  5. Using the scan tool, observe the Alternative Fuels Operation (AFO) Signal input data parameter located in the Engine Data - Gasoline list.

Does the data parameter indicate the AF ECM is in control of engine fueling?

--

Go to Step 14

Go to Step 13

12
  1. Turn OFF the ignition.
  2. Disconnect the Alternative Fuels ECM connectors.
  3. Turn ON the ignition, with the engine OFF.
  4. Using the scan tool, observe the Alternative Fuels Operation (AFO) Signal data parameter located in the Engine Data - Gasoline list.

Does the data parameter indicate the PCM is in control of engine fueling?

--

Go to Step 41

Go to Step 14

13
  1. Test the Alternative Fuels Operation (AFO) Signal circuit for an open or a high resistance condition.
  2. Inspect the gasoline Control Module connector for proper terminal contact.
  3. Repair the wiring or terminals as necessary.

Was a wiring or terminal repair necessary?

--

Go to Step 43

Go to Step 42

14
  1. Test the Alternative Fuels Operation (AFO) Signal circuit for a short to ground condition.
  2. Repair the wiring as necessary.

Was a wiring repair necessary?

--

Go to Step 43

Go to Step 41

15

Observe the idle control solenoid (ICS) output circuit status scan tool data parameter while the engine is operating on CNG.

Does the data parameter indicate OPEN?

--

Go to Step 16

Go to Step 23

16
  1. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G van Service Manual.
  2. Disconnect the idle control solenoid (ICS) connector. The ICS connector is red.
  3. Jumper the ICS connector terminals together using a fused jumper.
  4. Ensure that the engine is operating on CNG.

Does the data parameter indicate OPEN?

--

Go to Step 17

Go to Step 37

17
  1. Remove the jumper.
  2. Connect the J 35616-200 Unpowered Test Lamp between the ICS ignition relay power circuit terminal (A) and a known good ground.
  3. Ensure that the ignition is ON.

Is the test lamp illuminated?

--

Go to Step 18

Go to Step 36

18
  1. Test the ICS control circuit for an open condition.
  2. Inspect the Alternative Fuels ECM connector terminals for proper contact.
  3. Repair the wiring or terminals as necessary.

Was a wiring or terminal repair performed?

--

Go to Step 43

Go to Step 41

19

Observe the fuel control solenoid (FCS) output circuit status scan tool data parameter while the engine is operating on CNG.

Does the data parameter indicate OPEN?

--

Go to Step 20

Go to Step 25

20
  1. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G Van Service Manual.
  2. Disconnect the fuel control solenoid (FCS) connector. The FCS connector is black.
  3. Jumper the FCS connector terminals together using a fused jumper.
  4. Ensure that the engine is operating on CNG.

Does the data parameter indicate OPEN?

--

Go to Step 21

Go to Step 25

21
  1. Remove the jumper.
  2. Connect the J 35616-200 between the ICS ignition relay power circuit terminal (A) and a known good ground.
  3. Ensure that the ignition is ON.

Is the test lamp illuminated?

--

Go to Step 22

Go to Step 36

22
  1. Test the FCS control circuit for an open condition.
  2. Inspect the Alternative Fuels ECM connector terminals for proper contact.
  3. Repair the wiring or terminals as necessary.

Was a wiring or terminal repair performed?

--

Go to Step 43

Go to Step 41

23
  1. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G Van Service Manual.
  2. Ensure that the engine is operating on CNG.
  3. Disconnect the idle control solenoid (ICS) connector. The ICS connector is red.

Does the data parameter indicate OPEN?

--

Go to Step 37

Go to Step 24

24
  1. Test the control circuit for the shorted condition as indicated by the data parameter.
  2. Repair the wiring as necessary.

Was a wiring repair performed?

--

Go to Step 43

Go to Step 41

25
  1. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G Van Service Manual.
  2. Ensure that the engine is operating on CNG.
  3. Disconnect the fuel control solenoid (FCS) connector. The FCS connector is black.

Does the data parameter indicate OPEN?

--

Go to Step 38

Go to Step 26

26
  1. Test the control circuit for a shorted condition.
  2. Repair the wiring as necessary.

Was a wiring repair performed?

--

Go to Step 43

Go to Step 41

27
  1. Turn the ignition OFF.
  2. Disconnect the Alternative Fuels ECM connectors.
  3. Turn the ignition ON while with the engine OFF.
  4. Connect the J 39200 DMM test leads between the EVAP Canister Purge Enable Control circuit terminal and battery negative.
  5. Measure the voltage on the circuit.

Is the voltage within the value range specified?

4.8-5.2 V

Go to Step 40

Go to Step 28

28

Was the voltage greater than the value specified?

5.2 V

Go to Step 30

Go to Step 29

29
  1. Test the EVAP Canister Purge Enable Control circuit for an open or shorted to ground condition as indicated by the output data parameter.
  2. Inspect the PCM connector terminals for proper contact.
  3. Repair the wiring or terminals as necessary.

Was a wiring or terminal repair performed?

--

Go to Step 43

Go to Step 42

30
  1. Test the EVAP Canister Purge Enable Control circuit for a shorted to battery voltage condition.
  2. Repair the wiring as necessary.

Was a wiring repair performed?

--

Go to Step 43

Go to Step 42

31
  1. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G Van Service Manual.
  2. Disconnect the low pressure lock-off (LPL) solenoid connector.
  3. Connect the J 35616-200 between the LPL ignition relay power circuit terminal (A) and a known good ground.
  4. Turn the ignition ON, with the engine OFF.

Is the test lamp illuminated?

--

Go to Step 32

Go to Step 36

32
  1. Connect the J 35616-200 between the LPL ignition relay power circuit terminal (A) and the control circuit terminal (B).
  2. Start and idle the engine.
  3. Observe the test light as you command the LPL Open and Closed using the scan tool Alt. Fuels Special Function.

Does the test lamp operate as commanded?

--

Go to Step 39

Go to Step 33

33

Is the test lamp always illuminated?

--

Go to Step 34

Go to Step 35

34
  1. Test the control circuit for a shorted to ground condition.
  2. Repair the wiring as necessary.

Was a wiring repair performed?

--

Go to Step 43

Go to Step 41

35
  1. Test the control circuit for an open or shorted to voltage condition.
  2. Repair the wiring as necessary.

Was a wiring repair performed?

--

Go to Step 43

Go to Step 40

36

Repair the open ignition voltage supply circuit between the solenoid connector and the ignition relay circuit splice.

Is the repair complete?

--

Go to Step 43

--

37

Replace the idle control solenoid (ICS). Refer to Idle Control Solenoid Replacement .

Is the replacement complete?

--

Go to Step 43

--

38

Replace the fuel control solenoid (FCS). Refer to Fuel Control Solenoid Replacement .

Is the replacement complete?

--

Go to Step 43

--

39

Replace the lock-off solenoid. Refer to Low Pressure Lock-Off Solenoid Replacement .

Is the replacement complete?

--

Go to Step 43

--

40
  1. Inspect the Alternative Fuels ECM connectors for proper terminal contact.
  2. Repair the terminal contact as necessary.

Was a repair necessary?

--

Go to Step 43

Go to Step 41

41

Replace the Alternative Fuels ECM. Refer to Alternative Fuels Engine Control Module Replacement .

Is the replacement complete?

--

Go to Step 43

--

42

Important: The following Control Module replacement procedures must all be completed before attempting to operate the vehicle.

  1. Replace the gasoline Control Module (VCM/PCM or ECM). Refer to Powertrain Control Module Replacement .
  2. Program the replacement Control Module with the correct vehicle software and calibration.

    3. Important: In order to perform the variation learn procedure a switch-over to gasoline operation is necessary. Remove the CNG 20-amp fuse in order to perform the switch-over.

  3. Perform the Crankshaft Position System Variation Learn .

    4. All of the above procedures are located in the gasoline service manual.

Is the replacement complete?

--

Go to Step 43

--

43
  1. Using a scan tool, clear the DTC information from both Control Modules.
  2. Operate the vehicle under the Conditions for Running the DTC.
  3. Using the scan tool parameter DTC STATUS, ensure that this DTC runs.

Did this DTC run and pass?

--

System OK

Go to Step 2