GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 SLS 🢒 Engine 🢒 Engine Controls and Fuel - 2.8L, 3.0L, 3.2L, or 3.6L 🢒 DTC P2176

Circuit Description

The engine control module (ECM) controls the throttle valve by applying a varying voltage to the throttle actuator control (TAC) motor. The ECM monitors the actual throttle valve position using throttle position (TP) sensor 1 and 2. If the ECM detects that TP sensor 1 and 2 voltages are not within a specified range during the throttle learn procedure or the throttle learn procedure is not learned after an ECM replacement, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2176 Minimum Throttle Position Not Learned

Conditions for Running the DTC
    • The engine speed is less than 40 RPM.
    • The vehicle speed is 0 km/h (0 mph).
    • The engine coolant temperature (ECT) is between 5-85°C (41-185°F).
    • The intake air temperature (IAT) is more than 5-60°C (41-140°F).
    • The accelerator pedal position (APP) sensor angle is less than 14.9 percent.
    • The ignition 1 voltage is more than 10 volts.
    • DTC P2176 run continuously once the above conditions are met for more than 1 second.

Conditions for Setting the DTC
    • The ECM detects that the TP sensor 1 voltage is not between 0.2-0.9 volt during the throttle learn procedure.
        OR
    • The ECM detects that the TP sensor 2 voltage is not between 4.2-4.8 volts during the throttle learn procedure.
        OR
    • Any of the above conditions exist for more than 4 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC
    • A current DTC, last test failed, clears when the diagnostic runs and passes.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
    • Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
    • The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views .
    • Inspect for a condition in which the throttle valve may have been held open. For example, ice may have formed in the throttle bore.
    • The throttle valve is spring loaded to a slightly open position. The throttle valve should be open approximately 25 percent. This is referred to as the rest position. The throttle valve should not be completely closed, nor should the throttle valve be open any more than the specified amount. The throttle valve should move to the open or closed position without spring pressure. The throttle should NOT be free to move open or closed WITHOUT spring pressure. Replace the throttle body if any of these conditions are found.
    • If the conditions for running the DTC are out of range, this DTC will not be able to be cleared until the ECM learns the throttle position.
    • For an intermittent condition, refer to Intermittent Conditions .

Test Description

The number below refers to the step number on the diagnostic table.

  1. A TP sensor DTC may cause this DTC to set.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn the ignition switch to ON position, with the engine OFF.
  2. Clear the DTCs with a scan tool.
  3. Start the engine.
  4. Perform the following tests:
    5. • Rapidly depress the accelerator pedal from the rest position to the wide open throttle (WOT) position and release the pedal. Repeat the procedure several times.
    • Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.
  5. Observe the DTC information with a scan tool.

Does DTC P0121, P0122, P0123, P0221, P0222, or P0223 fail this ignition?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

Is DTC P0638 set?

Go to DTC P0638

Go to Step 4

4

Is DTC P2101 set?

Go to DTC P2101

Go to Step 5

5

    Important: This step is performing the Idle Learn procedure. Make sure the Conditions for Running the DTC in the supporting text are within the specified ranges. The engine coolant temperature (ECT) must be between 5-85°C (41-185°F) or the engine control module (ECM) will NOT perform the Idle Learn procedure.

  1. Turn OFF the ignition for 30 seconds.
  2. Turn ON the ignition, with the engine OFF for 1 minute.
  3. Turn OFF the ignition for 30 seconds.
  4. Turn the ignition switch to ON, with the engine OFF.
  5. Clear the DTCs with a scan tool.
  6. Start the engine.
  7. Perform the following tests:
    8. • Rapidly depress the accelerator pedal from the rest position to the WOT position and release the pedal. Repeat the procedure several times.
    • Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.
  8. Observe the DTC information with a scan tool.

Does DTC P0121, P0122, P0123, P0221, P0222, or P0223 set?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 6

6

Did DTC P2176 set?

Go to Step 7

Go to Step 8

7

Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .

Did you complete the replacement?

Go to Step 8

--

8
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 9

9

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK