Engine Controls - 8.1L - Diagnostics (Dtcs P0506-U0107): Diagnosis Chevrolet Silverado 1500

Circuit Description

The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle plate. In order to decrease idle speed the TAC system closes the throttle plate reducing airflow into the engine. In order to increase idle speed the TAC system opens the throttle plate allowing more airflow into the engine. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0506 Idle Speed Low
2. DTC P0507 Idle Speed High

Conditions for Running the DTC

1. DTCs P0068, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0171, P0172, P0200, P0220, P0300, P0336, P0401, P0404, P0405, P0442, P0446, P0452, P0453, P0641, P0651, P1516, P2101, P2135 are not set.
2. The engine is operating for at least 2 seconds.
3. The engine coolant temperature (ECT) is more than -40°C (-40°F).
4. The intake air temperature (IAT) is more than -40°C (-40°F).
5. The barometric pressure (BARO) is more than 65 kPa.
6. The system voltage is between 9-18 volts.
7. The vehicle speed is less than 4.8 km/h (3 mph).
8. This diagnostic runs continuously when the above conditions are met.

Conditions for Setting the DTC

1. The actual idle speed is approximately 150 RPM lower than or 100 RPM more than the desired idle speed.
2. The above condition is present for 15 seconds.

Action Taken When the DTC Sets

1. The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
2. The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

1. The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using a scan tool.

Diagnostic Aids

If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

This diagnostic applies to internal microprocessor integrity conditions within the powertrain control module (PCM). This diagnostic also addresses whether or not the PCM is not programmed.

This diagnostic procedure supports the following DTCs

1. DTC P0601 Control Module Read Only Memory (ROM)
2. DTC P0602 Control Module Not Programmed
3. DTC P0604 Control Module Random Access Memory (RAM)
4. DTC P0606 Control Module Internal Performance
5. DTC P2610 Control module Ignition Off Timer Performance

DTC P0601

1. The ignition switch is in the Run or Crank position.
2. DTC P0601 runs continuously when the above condition is met.

DTC P0602

1. The ignition switch is in the ON position.
2. DTC P0602 runs continuously when the above condition is met.

DTC P0604

1. The ignition switch is in the Run or Crank position.
2. DTC P0604 runs continuously when the above condition is met.

DTC P0606

1. The ignition switch is in the Run or Crank position, or the key is being turned OFF.
2. DTC P0606 runs continuously when the above condition is met.

DTC P2610

1. The PCM is powered down.
2. DTC P2610 runs once every time the key is turned OFF.

The PCM detects an internal failure or incomplete programming for more than 5 seconds.

Action Taken When DTC P2610 Sets

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

The powertrain control module (PCM) provides 5 volts to the following sensors

1. The engine oil pressure (EOP) sensor
2. The manifold absolute pressure (MAP) sensor

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0641 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0641 5-Volt Reference 1 Circuit

1. The engine is running.
2. DTC P0641 runs continuously when the above condition is met.

The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit for more than 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The control module monitors the MIL control circuit for conditions that are incorrect for the commanded state of the MIL. For example, a failure condition exists if the control module detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON. If the control module detects an improper voltage on the MIL control circuit, DTC P0650 will set.

This diagnostic procedure supports the following DTC

DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

1. The engine speed is more than 400 RPM.
2. DTC P0650 runs continuously when the above condition is met.

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for more than 5 seconds.

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
3. Clear the MIL and the DTC with a scan tool.

The powertrain control module (PCM) provides 5 volts to the following sensors

1. The air conditioning (A/C) pressure sensor.
2. The fuel tank pressure (FTP) sensor, if equipped.

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore, a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0651 sets.

This diagnostic procedure supports the following DTC

DTC P0651 5-Volt Reference 2 Circuit

1. The engine is running.
2. DTC P0651 runs continuously when the above condition is met.

The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit for more than 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0651

The transmission control module (TCM) malfunction indicator lamp (MIL) request circuit signals the powertrain control module (PCM) that the TCM is requesting MIL illumination.

This diagnostic procedure supports the following DTC

DTC P0802 Transmission Control Module (TCM) MIL Request Circuit

1. The ignition is ON for less than 7 seconds.
2. The ignition voltage is more than 11 volts.
3. DTC P0802 runs continuously when the above conditions are met.

The PCM is detecting an incorrect voltage level on the TCM MIL request circuit.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0802

The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually two individual APP sensors within one housing. Two separate signal circuits are used to connect the accelerator pedal sensor assembly and the throttle actuator control (TAC) module.

If only one APP sensor DTC is set, the redundant APP systems allow the TAC system to continue operating normally. This DTC sets if the powertrain control module (PCM) detects a condition with more than one APP sensor. One APP sensor DTC will not cause the Reduced Engine Power message to be displayed. Two APP sensor DTCs for the same sensor also will not cause the Reduced Engine Power message to be displayed. However, if two or more DTCs are set involving more than one APP sensor, this DTC will set and the Reduced Engine Power message is displayed.

This diagnostic procedure supports the following DTC

DTC P1125 Accelerator Pedal Position (APP) System

1. DTCs P2108 or U0107 are not set.
2. The ignition switch is in the Crank or Run position.
3. The ignition voltage is greater than 5.23 volts.
4. DTC P1125 runs continuously when the above conditions are met.

1. Two or more APP sensors are out of range. OR
2. The APP sensors disagree.
3. The above condition is present for less than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
2. The APP sensor 1 and the throttle position (TP) sensor 1 5-volt reference circuits are internally connected within the TAC module.
3. The APP sensor 2 and the TP sensor 2 5-volt reference circuits are internally connected within the TAC module.
4. When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Remember this if you review the information stored in Captured Info.
5. For an intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

DTC P1125

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. The PCM monitors the number of rich-to-lean and lean-to-rich transitions. If the PCM detects that the number of transitions were less than a specified value, DTC P1133 sets for HO2S bank 1 sensor 1, or DTC P1153 sets for HO2S bank 2 sensor 1.

This diagnostic procedure supports the following DTCs

1. DTC P1133 HO2S Insufficient Switching Bank 1 Sensor 1
2. DTC P1153 HO2S Insufficient Switching Bank 2 Sensor 1

1. DTCs P0053, P0054, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0220, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The ECT Sensor parameter is more than 60°C (140°F).
3. The EVAP Purge Solenoid Command parameter is more than 1 percent.
4. The MAF Sensor parameter is between 20-55 g/s.
5. The Engine Speed parameter is between 1,200-3,000 RPM.
6. The TP Indicated Angle parameter is 5 percent more than the value observed at idle.
7. The Loop Status parameter is closed.
8. The Ignition 1 Signal parameter is between 10-18 volts.
9. The Fuel Tank Level Remaining parameter is more than 10 percent.
10. The Engine Run Time parameter is more than 160 seconds.
11. This diagnostic runs one time per drive cycle once the above conditions are met.

The PCM detects that the affected HO2S lean-to-rich or rich-to-lean transitions are less than a calibrated value for a 100 second monitoring period.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. The PCM monitors the rich-to-lean and lean-to-rich transition time. A transition is defined as, the HO2S voltage changes from above 625 mV to below 250 mV or from below 250 mV to above 625 mV. If the PCM detects that the difference between the rich-to-lean average transition time and lean-to-rich average transition time is more than a specified value, DTC P1134 sets for HO2S bank 1 sensor 1, or DTC P1154 sets for HO2S bank 2 sensor 1.

This diagnostic procedure supports the following DTCs

1. DTC P1134 HO2S Transition Time Ratio Bank 1 Sensor 1
2. DTC P1154 HO2S Transition Time Ratio Bank 2 Sensor 1

1. DTCs P0053, P0054, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0220, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The ECT Sensor parameter is more than 60°C (140°F).
3. The EVAP Purge Solenoid Command parameter is more than 1 percent.
4. The MAF Sensor parameter is between 20-55 g/s.
5. The Engine Speed parameter is between 1,200-3,000 RPM.
6. The TP Indicated Angle parameter is 5 percent more than the value observed at idle.
7. The Loop Status parameter is closed.
8. The Ignition 1 Signal parameter is between 10-18 volts.
9. The Fuel Tank Level Remaining parameter is more than 10 percent.
10. The Engine Run Time parameter is more than 160 seconds.
11. This diagnostic runs one time per drive cycle once the above conditions are met.

The PCM detects that the difference between the HO2S rich-to-lean average transition time and the lean-to-rich average transition time is more than a calibrated value for a 100 second monitoring period.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

This diagnostic procedure supports the following DTC

DTC P1380 Misfire Detected - Rough Road Data Not Available

1. The vehicle speed is more than 8 km/h (5 mph).
2. The engine load is less than 60 percent.
3. The engine misfire is detected and DTC P0300 is set with the MIL illuminated.
4. The engine speed is less than 7,000 RPM.
5. DTC P1380 runs continuously when the above conditions are met.

An ABS malfunction exists for more than 45 seconds, preventing the PCM from receiving rough road detection data.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
3. The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

DTC P1380

This diagnostic procedure supports the following DTC

DTC P1381 Misfire Detected - No Communication with Brake Control Module

1. The vehicle speed is above 8 km/h (5 mph).
2. The engine speed is below 7,000 RPM.
3. The engine load is less than 60 percent.
4. Engine misfire is detected and DTC P0300 is set with the MIL illuminated.
5. DTC P1381 runs continuously when the above conditions are met.

The PCM cannot communicate with the brake control module for more than 45 seconds.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
3. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

DTC P1381

The predicted throttle position (TP) is compared to the actual throttle position. The two values should be within a calibrated range of each other. Both the powertrain control module (PCM) and the throttle actuator control (TAC) module redundantly monitor the predicted and actual throttle position. This DTC sets if the PCM detects an out of range condition between the predicted and actual throttle position.

This diagnostic procedure supports the following DTC

DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance

1. DTC U0107 is not set.
2. The ignition switch is in the crank or run position.
3. The ignition voltage is more than 5.23 volts.
4. The TAC System is not in the battery saver mode.
5. This diagnostic runs continuously when the above conditions are met.

1. The TAC module detects that the predicted and the actual throttle positions are not within a calibrated range of each other.
2. The PCM and the TAC cannot determine the throttle position.
3. Both of the TP sensors are invalid.
4. All of the above conditions are met for more than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
2. Verify that the starting and charging systems are operating properly. Low system voltage can cause this DTC to set.
3. When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
4. For an intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The commanded throttle position (TP), based on accelerator pedal position (APP) and possibly other limiting factors, is compared to the actual TP. The 2 values should be within a calibrated range of each other. Both the powertrain control module (PCM) and the throttle actuator control (TAC) module redundantly monitor the commanded and actual TP. This DTC sets if the PCM detects an out-of-range condition between commanded and actual pedal position.

This diagnostic procedure supports the following DTC

DTC P2101 Control Module Throttle Actuator Position Performance

1. DTCs P0601, P0602, P0604, P0606, P1516, P2108, U0107 are not set.
2. DTCs P0120 and P0220 are not active at the same time.
3. The ignition switch is in the crank or run position.
4. The ignition voltage is more than 8.5 volts.
5. The TAC System is not in the battery saver mode.
6. This diagnostic runs continuously when the above conditions are met.

1. The PCM detects that the commanded and actual throttle positions are not within a calibrated range of each other.
2. The above condition is met for less than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect for mechanical concerns or binding that may be temperature related. Components may not move freely in extreme heat or cold due to the presence of contaminants or ice formation.
2. Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
3. When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
4. For an intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The throttle actuator control (TAC) module contains data which is essential for proper TAC System operation. The TAC module continuously tests the integrity of this data. When the TAC module is unable to write or read data to and from random access memory (RAM), or the TAC module is unable to correctly read data from the flash memory or an internal TAC module processor fault is detected, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P2108 Throttle Actuator Control (TAC) Module Performance

1. DTC U0107 is not set.
2. The ignition switch is in the crank or run position.
3. The ignition voltage is greater than 6 volts.
4. This diagnostic runs continuously when the above conditions are met.

1. The TAC module determines that an internal data test did not pass.
2. The above condition is met for more than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Verify that the starting and charging systems are operating properly. Low system voltage can cause this DTC to set.
2. Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
3. When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.

The accelerator pedal position (APP) sensor 1 is a potentiometer type sensor with the following three circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The control module provides the APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensor then provides the control module a signal voltage proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 signal or APP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P2120 Accelerator Pedal Position (APP) Sensor 1 Circuit

1. DTCs P0601, P0602, P0606, P2108, or U0107 are not set.
2. The ignition switch is in the crank or run position.
3. The ignition voltage is more than 5.23 volts.
4. This diagnostic runs continuously when the above conditions are met.

1. The APP sensor 1 voltage is less than 0.24 volts or more than 4.49 volts. OR
2. The 5-volt reference is less than 4.54 volts or more than 5.21 volts.
3. One of the above conditions is present for more than 1 second.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. If one or more APP sensor DTCs are set, the following occurs: The control module commands Reduced Engine Power mode. The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. OR The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle. The message center displays Reduced Engine Power.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
2. When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
3. For an intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The accelerator pedal position (APP) sensor 1 and APP sensor 2 are potentiometer type sensors, each with the following circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The control module provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is also low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 signal and the APP sensor 2 signal circuits are out of correlation, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P2121 Accelerator Pedal Position (APP) Sensor 1 Performance

1. DTCs P0606, P2108, or U0107 are not set.
2. The ignition switch is in the crank or run position.
3. The ignition voltage is more than 5.23 volts.
4. This diagnostic runs continuously when the above conditions are met.

1. APP sensor 1 disagrees with APP sensor 2 by more than 10.5 percent.
2. The above condition is present for more than 1 second.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. If one or more APP sensor DTCs are set for a single APP sensor, the following occurs: The control module commands Reduced Engine Power mode. The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle. The message center displays Reduced Engine Power.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
2. When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
3. For an intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The accelerator pedal position (APP) sensor 2 is a potentiometer type sensor with the following circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The control module provides the APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensor then provides the control module a signal voltage proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 2 signal or the APP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P2125 Accelerator Pedal Position (APP) Sensor 2 Circuit

1. DTCs P0601, P0602, P0606, P2108, U0107 are not set.
2. The ignition switch is in the crank or run position.
3. The ignition voltage is more than 5.23 volts.
4. This diagnostic runs continuously when the above conditions are met.

1. The APP sensor 2 voltage is less than 0.24 volt or more than 4.49 volts. OR
2. The 5-volt reference is less than 4.54 volts or more than 5.21 volts.
3. One of the above conditions is present for more than 1 second.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. If one or more APP sensor DTCs are set, the following occurs: The control module commands Reduced Engine Power mode. The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. OR The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle. The message center displays Reduced Engine Power.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
2. When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
3. For an intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The throttle position (TP) sensors 1 and 2 are potentiometer type sensors each with three circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The TP sensors are used to determine the throttle plate angle for various engine management systems. The control module provides each TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensors then provide the control module with signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. When the control module detects that TP sensor 1 signal and TP sensor 2 signals disagree or signal voltages are outside the predetermined range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P2135 Throttle Position (TP) Sensor 1-2 Correlation

1. DTCs P2108, or U0107 not set.
2. The ignition switch is in the crank or run position.
3. The ignition voltage is more than 5.23 volts.
4. This diagnostic runs continuously when the above conditions are met.

1. The TP sensor 2 disagrees with the TP sensor 1 by more than 7.5 percent.
2. The above condition is present for more than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
2. When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
3. If this DTC is determined to be intermittent, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The accelerator pedal position (APP) sensors 1 and 2 are located within the accelerator pedal assembly. Each sensor has the following circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

This provides the powertrain control module (PCM) with a signal voltage proportional to accelerator pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the low reference and increases as the pedal is actuated.

This diagnostic procedure supports the following DTC

DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation

1. The battery voltage is more than 5.23 volts.
2. DTCs P2120 or P2125 are not set.
3. The accelerator pedal is leaving the idle position.
4. DTC P2138 runs continuously when the above conditions are met.

1. The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value.
2. The above condition is met for more than 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The PCM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and does not fail.
2. A History DTC clears after 40 consecutive warm up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.
3. The scan tool clears the MIL/DTC.

1. The PCM compares the signal of each of the accelerator pedal position sensor to each other throughout the entire range of operation. Clear the DTCs and actuate the pedal through the entire range with the ignition ON and the engine OFF.
2. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the PCM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.
3. For intermittent conditions, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .

The secondary fuel pump is located in the rear fuel tank. The secondary fuel pump is powered by a secondary fuel pump relay. Fuel is transferred from the rear fuel tank to the front fuel tank in order to ensure all of the usable fuel volume is available to the primary fuel pump. The secondary fuel pump relay supply voltage is received from the primary fuel pump relay when the primary fuel pump is energized. This DTC sets when the powertrain control module (PCM) commands the secondary fuel pump ON and a predetermined change in both the front and rear fuel level sensors does not occur.

This diagnostic procedure supports the following DTC

DTC P2636 Fuel Transfer Pump Flow Insufficient

1. DTCs P0461, P0462, P0463, P2066, P2067, P2068 are not set.
2. The vehicle speed is 0 km/h (0 mph).
3. The engine has been idling for more than 2 minutes and 20 seconds.
4. The primary fuel level is less than 60 L (15.8 gal).
5. The secondary fuel level is more than 3 L (2.6 gal).

The PCM does not detect a change of 4 L (1.06 gal), in both the primary and the secondary fuel level sensors, with the secondary pump commanded ON for 120 seconds.

1. The PCM stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream.

The HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2 are used for catalyst monitoring. This diagnostic runs once per ignition cycle. This diagnostic consists of two tests, a passive test and an intrusive test. During the passive test, if the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 voltage transitions below 349 mV and above 710 mV, the DTC will pass for this ignition cycle. If the DTC does not pass during the passive test, the intrusive test will begin. During the intrusive test, the control module will force the air-to-fuel ratio rich and/or lean. The control module then waits for a predicted response from the HO2S. If the HO2S voltage transitions below 349 mV and/or above 710 mV, the DTC will pass for this ignition cycle. If the control module does not receive the expected response from the HO2S, DTC P2A01 will set for HO2S bank 1 sensor 2 or DTC P2A04 will set for HO2S bank 2 sensor 2.

This diagnostic procedure supports the following DTCs

1. DTC P2A01 HO2S Circuit Bank 1 Sensor 2
2. DTC P2A04 HO2S Circuit Bank 2 Sensor 2

DTCs P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0200, P0442, P0443, P0446, P0449, P0455, P0496, P1133, P1134, P1153, P1154 are not set.

Passive Test

1. The engine is running.
2. The engine run time is more than 2 seconds.
3. This diagnostic runs one time per drive cycle when the above conditions are met.

Intrusive Test

1. The engine run time is more than 218 seconds.
2. The Ignition 1 Signal parameter is between 10-18 volts.
3. The Engine Speed parameter is between 900-5,000 RPM.
4. The MAF Sensor parameter is between 5-100 g/s.
5. The Vehicle Speed parameter is between 24-131 km/h (15-82 mph).
6. The Short Term FT Bank 1 and Bank 2 parameter is between -4 and +4 percent.
7. The maximum number of intrusive attempts is less than 100.
8. This diagnostic runs one time per drive cycle when the above conditions are met for 3 seconds.

1. The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 did not transition below 349 mV and above 710 mV during the passive test.
2. One of the following tests fail: Lean Intrusive Test The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is more than 349 mV for 60 seconds. The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is less than 300 mV. OR Rich Intrusive Test The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is less than 710 mV for 60 seconds. The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is more than 600 mV.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The throttle actuator control (TAC) module and the powertrain control module (PCM) communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity, but also adequate system voltage. This diagnostic test monitors the accuracy of the serial data transmitted between the TAC module and the PCM. If the PCM detects a loss of data or invalid data, this DTC sets.

This diagnostic procedure supports the following DTC

DTC U0107 Lost Communication with Throttle Actuator Control (TAC) Module

1. The ignition switch is in the Crank or Run position.
2. The ignition voltage is more than 5.23 volts.
3. This diagnostic runs continuously when the above conditions are met.

1. Invalid or missing serial data messages are detected for a predetermined amount of time.
2. The above condition is met for more than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTC U0107 sets if the battery voltage is low. If the customer's concern is slow cranking or no crank because battery voltage is low, ignore DTC U0107. Clear any DTCs from memory that may have set from the low battery voltage condition.
2. DTC U0107 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness - i.e. cruise, brake. An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
3. DTC U0107 sets if the TAC module ignition feed circuit is shorted to a B+ supply circuit. The TAC module stays powered-up when the ignition switch is turned OFF. When the ignition switch is turned ON, the TAC module is powered-up before the PCM. DTC U0107 sets because no communication is detected by the TAC module from the PCM. Inspect related circuits for being shorted to a B+ supply circuit.
4. Inspect the TAC module power and ground circuits and the TAC module/PCM serial data circuits for intermittent connections.
5. Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
6. When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than one DTC. Remember this if you review the stored information in Capture Info.
7. For an intermittent condition, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-238178-S33329058682006072400000) .