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Engine Control System & Fuel System - 4.8l, 5.3l, and 6.0l - DTC p2138 to DTC u0107 Chevrolet Chevy Express H1500

Testing & Diagnostics ~1960 words

Circuit Description

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.

DTC Descriptor

This diagnostic procedure supports the following DTC

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

Conditions for Running the DTC

  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.

Conditions for Setting the DTC

  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.

Action Taken When the DTC Sets

  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.

Conditions for Clearing the MIL/DTC

  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.

Diagnostic Aids

  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»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor) .

Test Description

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

  1. 2: Any circuit faults on either APP sensor 1 or 2 will set one of the DTCs listed. Refer to the appropriate table for diagnosis.
StepActionValuesYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1Did you perform the Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle
2Observe the DTC information with a scan tool. Is DTC P0120, P0220, P0641, P0651, P2120, or P2125 also set?Go to Diagnostic Trouble Code (DTC) List - VehicleGo to Step 3
3Turn OFF the ignition. Disconnect the accelerator pedal position (APP) sensor electrical connector. Disconnect the powertrain control module (PCM). Use a DMM to measure the resistance of the following circuits for each of the APP sensors: The low reference circuit The signal circuit The 5-volt reference circuit Did any of the circuits measure more than the specified value?5 ohmsGo to Step 5Go to Step 4
4Test for a short between any of the circuits in the APP sensor harness. Repair the circuit as necessary. Refer to Wiring Repairs . Did you find and correct the condition?Go to Step 7Go to Step 6
5Repair the high resistance in the circuit. Refer to Wiring Repairs . Did you complete the repair?Go to Step 7
6Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement?Go to Step 7
7Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. 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 2Go to Step 8
8Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) List - VehicleSystem OK

DTC P2138

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 less than 349 mV and greater than 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 less than 349 mV and/or greater than 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.

DTC Descriptors

This diagnostic procedure supports the following DTCs

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

Without RPO JL4

DTCs P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, 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.

With RPO JL4

DTCs P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, 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, P1125, P1133, P1134, P1153, P1154, P1516, P2101, P2108, P2135, U0107 are not set.

Passive Test

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

Intrusive Test

  1. The Engine Run Time parameter 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. The above conditions are met for 3 seconds.
  9. This diagnostic runs one time per drive cycle when the above conditions are met.
  1. The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 did not transition less than 349 mV and greater than 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 greater than 349 mV for 60 seconds. The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is less than 300 mV.

Rich Intrusive Test

  1. The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is less than 710 mV for 60 seconds.
  2. The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is greater 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 number below refers to the step number on the diagnostic table.

  1. 2: If the voltage does not change more that the specified value, the condition is present.
StepActionValue(s)YesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views
1Did you perform the Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle
2Start the engine. Allow the engine to reach operating temperature. Refer to Scan Tool Data List . Operate the engine at 1,500 RPM for 30 seconds. While observing the affected HO2S voltage parameter with a scan tool, quickly cycle the throttle from closed throttle to wide open throttle, 3 times. Did the HO2S voltage parameter change more than the specified value?200 mVGo to Step 3Go to Step 4
3Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. 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 4Go to Testing for Intermittent Conditions and Poor Connections
4Turn OFF the ignition. Disconnect the affected heated oxygen sensor (HO2S). Turn ON the ignition, with the engine OFF. Observe the HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter less than the specified value?100 mVGo to Step 6Go to Step 5
5Observe the HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter more than the specified value?800 mVGo to Step 7Go to Step 8
6Test the HO2S high signal circuit for a short to ground. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Circuit Testing Wiring Repairs Did you find and correct the condition?Go to Step 20Go to Step 9
7IMPORTANT: The sensor may be damaged if the circuit is shorted to a voltage source. Test the HO2S high signal circuit for a short to voltage. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Circuit Testing Wiring Repairs Did you find and correct the condition?Go to Step 20Go to Step 17
8Measure the voltage from the low signal circuit of the HO2S harness connector on the engine harness side to a good ground with a DMM. Refer to Circuit Testing . Is the voltage more than the specified value?2 VGo to Step 10Go to Step 11
9Test the HO2S high signal circuit for a short to the HO2S low signal circuit. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Circuit Testing Wiring Repairs Did you find and correct the condition?Go to Step 20Go to Step 17
10Test the HO2S low signal circuit for a short to voltage. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Circuit Testing Wiring Repairs Did you find and correct the condition?Go to Step 20Go to Step 17
11Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S harness connector on the engine harness side and a good ground. Observe the HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter less than the specified value?100 mVGo to Step 12Go to Step 14
12Remove the jumper wire from the previous step. Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S harness connector on the engine harness side and the low signal circuit of the HO2S harness connector on the engine harness side. Observe the HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter less than the specified value?100 mVGo to Step 15Go to Step 13
13Test the HO2S low signal circuit for an open or high resistance. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Circuit Testing Wiring Repairs Did you find and correct the condition?Go to Step 20Go to Step 17
14Test the HO2S high signal circuit for an open or high resistance. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Circuit Testing Wiring Repairs Did you find and correct the condition?Go to Step 20Go to Step 17
15The HO2S may be detecting a rich exhaust condition, a lean exhaust condition, or the HO2S may be contaminated. Inspect for the following conditions: NOTE: Refer to Silicon Contamination of Heated Oxygen Sensors Notice . A silicon contaminated HO2S Any water intrusion into the HO2S connector An exhaust leak between the HO2S and the engine Any vacuum leaks Engine oil contaminated with fuel An incorrect fuel pressure-Refer to Fuel System Diagnosis . Any lean or rich fuel injectors-Refer to Fuel Injector Balance Test with Tech 2 . An inaccurate mass air flow (MAF) sensor-Refer to Scan Tool Data List . Repair any of the above or similar engine conditions as necessary. Did you find and correct the condition?Go to Step 20Go to Step 16
16Test for shorted terminals and for poor connections at the HO2S. Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Testing for Intermittent Conditions and Poor Connections Connector Repairs Did you find and correct the condition?Go to Step 20Go to Step 18
17Test for shorted terminals and for poor connections at the powertrain control module (PCM). Refer to the following procedures: Heated Oxygen Sensor Wiring Repairs Testing for Intermittent Conditions and Poor Connections Connector Repairs Did you find and correct the condition?Go to Step 20Go to Step 19
18Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . Did you complete the replacement?Go to Step 20
19Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?Go to Step 20
20Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. 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 2Go to Step 21
21Observe the Capture Info with a scan tool. Have any DTCs not been diagnosed?Go to Diagnostic Trouble Code (DTC) List - VehicleSystem OK
IMPORTANT
The sensor may be damaged if the circuit is shorted to a voltage source.

DTC P2A01 or P2A04

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, DTC U0107 sets.

This diagnostic procedure supports the following DTC

DTC U0107 Lost Communications 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. DTC U0107 runs continuously once the above conditions are met.
  1. Invalid or missing serial data messages are detected.
  2. The above condition is met for more than 0.83 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.
IMPORTANTReprogramming the PCM may cause a communication error between the PCM and the TAC. If the PCM detects a communication error, DTC U0107 sets. Clear any DTCs from the memory that may have been set by reprogramming.
  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. For an intermittent condition, refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor) .

The numbers below refer to the step numbers on the diagnostic table.

  1. 3: Increasing the engine speed to 3,000 RPM aids in locating a shorted throttle actuator motor control circuit. Depending on the polarity of the throttle actuator motor transistors, this DTC may not set with a fault in the control circuits. The throttle actuator motor is a bi-directional DC motor. Raising the engine speed changes the polarity of the transistors in the throttle actuator motor. This occurs because one set of the transistors is low, 0 volts, and the other set is high, B+. Therefore, if one set of transistors is at a low voltage and the corresponding circuit is shorted low, DTC U0107 will not set. When the polarity of the transistors change, this DTC sets. If this DTC does not fail this ignition, continue to monitor this DTC status while moving related harnesses and connectors.
  2. 24: Locating and repairing an individual condition may correct more than one DTC.
StepActionValuesYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views
1Did you perform the Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle
2Is DTC P0604 also set?Go to DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610Go to Step 3
3Start the engine. Increase the engine speed to 3,000 RPM, if possible. Observe the DTC Info parameter with a scan tool. Did the DTC fail this ignition?Go to Step 4Go to Diagnostic Aids
4Measure the voltage from the throttle actuator control (TAC) Ignition 1 voltage circuit of the TAC module to a good ground with a DMM. Is the voltage within the specified value?B+Go to Step 5Go to Step 8
5Turn OFF the ignition. Disconnect the throttle actuator motor harness connector. Turn ON the ignition, with the engine OFF. Measure the voltage at both throttle actuator motor control circuits to a good ground with a DMM. Refer to Circuit Testing . Is the voltage on both circuits within the specified range?1 V-1.7 VGo to Step 12Go to Step 6
6Measure the voltage at both throttle actuator motor control circuits to a good ground, with a DMM. Is the voltage on both circuits above the specified value?1.7 VGo to Step 9Go to Step 7
7Test the throttle actuator motor control circuits for a short to ground at the TAC module 16-way harness connector with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 18
8Test the TAC module ignition feed circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 22
9Test for an open or high resistance in the TAC module ground circuit with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 10
10Test for a short between each throttle actuator motor control circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 11
11Test for a short to voltage at both throttle actuator motor control circuits with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 19
12Measure the voltage from the serial data circuits of the TAC module to a good ground with a DMM. Is the voltage within the specified range for both circuits?0-4.5 VGo to Step 13Go to Step 15
13Test both serial data circuits at the TAC module 16-way harness connector for continuity to ground with a DMM. Does the DMM indicate the specified value for both circuits?O.L.Go to Step 17Go to Step 14
14Test both serial data circuits at the TAC module 16-way connector for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 15
15Test for a short between both serial data circuits and all other circuits at the powertrain control module (PCM) and TAC module harness connectors with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 16
16Test for a short to voltage on both serial data circuits at the TAC module 16-way connector with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 19
17Test each serial data circuit between the TAC module 16-way harness connector and the PCM harness connector for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?Go to Step 23Go to Step 18
18Test for an intermittent and for a poor connections at the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals . Did you find and correct the condition?Go to Step 23Go to Step 20
19Test for an intermittent and for poor connections at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals . Did you find and correct the condition?Go to Step 23Go to Step 21
20Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement?Go to Step 23
21Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?Go to Step 23
22Replace the junction block. Refer to Body Wiring Harness Junction Block Replacement . Did you complete the replacement?Go to Step 23
23Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine 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 2Go to Step 24
24Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) List - VehicleSystem OK

DTC U0107

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