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Engine Control System Diagnosis - 4.8l, 5.3l & 6.0l (DTC p2101 to DTC u0107) Chevrolet Chevy Express G3500

Testing & Diagnostics ~3878 words

Circuit Description

The commanded throttle position (TP), based on accelerator pedal position (APP) and possibly other limiting factors, is compared to the actual TP. 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 commanded and actual TP. This DTC sets if the PCM detects an out-of-range condition between the commanded and the actual throttle position.

Conditions for Running the DTC

  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.

Conditions for Setting the DTC

  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.

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 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.

Diagnostic Aids

  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 «Intermittent Conditions»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-troubleshooting__intermittent-conditions) .

Test Description

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

  1. 4: If the TP indicated angle does not follow the movement of the throttle blade and no TP sensor DTCs are set, there is a mechanical condition with the throttle shaft or the TP sensor.
  2. 15: Locating and repairing an individual condition may correct more than 1 DTC.
StepActionYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1Did you perform the Diagnostic System Check - Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2Is DTC U0107 also set?Go to DTC U0107Go to Step 2
3IMPORTANT: The next test must be started within 15 seconds after the ignition is turned ON. Turn OFF the ignition for 15 seconds. Turn ON the ignition, with the engine OFF. Observe the throttle position (TP) sensor 1 and TP sensor 2 angle parameters with a scan tool. Slowly depress the accelerator pedal to wide open throttle (WOT) and slowly return the pedal to the released position. Does the scan tool indicate both angle parameters increasing as the pedal is depressed to WOT and decreasing as the pedal is moved to the released position?Go to Diagnostic AidsGo to Step 4
4Turn OFF the ignition. Remove the air inlet duct from the throttle body. Disconnect the throttle body harness connector. Connect the jumper wires between the TP sensor terminals of the throttle body harness connector and the corresponding TP sensor terminals of the throttle body. Turn ON the ignition with the engine OFF. Open the throttle blade to WOT, then to the closed position by hand. Observe the TP sensor 1 and the TP sensor 2 angle parameters with a scan tool. Does the scan tool indicate both angle parameters increasing as the throttle plate is moved to WOT, and decreasing as the throttle plate is moved to the closed position?Go to Step 5Go to Step 12
5Turn OFF the ignition. Disconnect the throttle actuator control (TAC) module harness connector containing the TAC motor circuits. Turn ON the ignition, with the engine OFF. Test the TAC motor circuits for a short to voltage with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 14Go to Step 6
6Test each TAC motor circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 14Go to Step 7
7Test each TAC motor circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 14Go to Step 8
8Disconnect the other TAC module harness connector. Remove all jumper wires. Test for a short between each TAC motor circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 14Go to Step 9
9Turn OFF the ignition. Connect the TAC module. Connect a test lamp between the 2 TAC motor circuits at the TAC motor harness connector. Turn ON the ignition, with the engine OFF, and observe the test lamp. Did the test lamp illuminate briefly when the ignition was turned ON?Go to Step 10Go to Step 12
10Inspect for poor connections at the TAC motor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 14Go to Step 11
11Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement?Go to Step 14
12Inspect for poor connections at the TAC module harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 14Go to Step 13
13Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement?Go to Step 14
14Clear 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 15
15Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) ListSystem OK
IMPORTANT
The next test must be started within 15 seconds after the ignition is turned ON.

DTC P2101

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.

  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.
  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 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.

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

  1. 4: Locating and repairing an individual condition may correct more than one DTC.
StepActionYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1Did you perform the Diagnostic System Check - Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2Replace the throttle actuator control (TAC) module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement?Go to Step 3
3Clear 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 4
4Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) ListSystem OK

DTC P2108

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.

  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.
  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.

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.
  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 «Intermittent Conditions»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-troubleshooting__intermittent-conditions) .

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

  1. 12: This test isolates whether the short is to another TAC system circuit in the harness or within the TAC module.
  2. 26: 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.
StepActionValuesYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1Did you perform the Diagnostic System Check-Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2IMPORTANT: If DTCs P0120 or U0107 is also set, refer to the appropriate DTC for further diagnosis. Turn ON the ignition with the engine OFF, and with your foot OFF the accelerator pedal. Observe the accelerator pedal position (APP) sensor 1 voltage with a scan tool. Does the scan tool indicate the APP sensor 1 voltage is within the specified values?0.24-2.24 VGo to Step 3Go to Step 6
3Depress the accelerator pedal to the wide open throttle (WOT) position. Does the scan tool indicate APP sensor 1 voltage within the specified values?0.24-4.49 VGo to Step 4Go to Step 6
4Turn OFF the ignition for 30 seconds. Turn ON the ignition, with the engine OFF. Select the DTC option using the scan tool. Lightly touch and move the related engine wiring harnesses and connectors while monitoring the DTC information. Did this DTC fail this ignition during the above test?Go to Step 24Go to Step 5
5Continue to observe the DTC information. Depress the accelerator pedal to WOT, then return the pedal to the rest position. Did this DTC fail this ignition during the above test?Go to Step 19Go to Diagnostic Aids
6Disconnect the APP sensor harness connector. Does the scan tool indicate the APP sensor 1 voltage is at the specified value?0 VGo to Step 7Go to Step 11
7Connect a test lamp between the APP sensor 1 signal circuit and B+. Does the scan tool indicate the APP sensor 1 voltage is at the specified value?5 VGo to Step 8Go to Step 13
8Test the APP sensor 1 5-volt reference circuit for voltage with a DMM. Does the DMM indicate voltage within the specified values?4.54-5.21 VGo to Step 10Go to Step 9
9Turn OFF the ignition. Disconnect the throttle actuator motor harness connector. Remove the air inlet duct from the throttle body assembly. Turn ON the ignition, with the engine OFF, Rotate the throttle blade by hand to WOT and hold. Test the APP sensor 1 5-volt reference circuit for voltage with a DMM. Does the DMM indicate voltage within the specified values?4.54-5.21 VGo to Step 21Go to Step 16
10Connect a fused jumper between the APP sensor 1 low-reference circuit and the APP sensor 1 5-volt reference circuit. Observe the throttle position (TP) sensor 1 voltage parameter with a scan tool. Does the scan tool indicate TP sensor 1 voltage at the specified value?0 VGo to Step 19Go to Step 17
11Turn OFF the ignition. Disconnect the throttle actuator control (TAC) module harness connector containing the APP sensor circuits. Turn ON the ignition, with the engine OFF. Test the APP sensor 1 signal circuit for a short to voltage with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 12
12Turn OFF the ignition. Disconnect the other TAC module harness connector. Test for a short between the APP sensor 1 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 22
13Turn OFF the ignition. Disconnect the TAC module harness connector containing the APP sensor circuits. Test the APP sensor 1 signal circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 14
14Test the APP sensor 1 signal circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 15
15Turn OFF the ignition. Disconnect the other TAC module harness connector. Test for a short between the APP sensor 1 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 22
16Turn OFF the ignition. Disconnect the TAC module connector containing the APP sensor circuits. Test the APP sensor 1 5-volt reference circuit for the following conditions with a DMM: An open A short to ground High resistance Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 22
17Disconnect the TAC module connector containing the APP sensor circuits. Test the APP sensor 1 low-reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 18
18Test the TAC module ground circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 22
19Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 20
20Replace the APP sensor assembly. Refer to Accelerator Pedal Position (APP) Sensor Replacement . Did you complete the replacement?Go to Step 25
21Did DTC P0120 set while performing Step 9?Go to DTC P0120Go to Step 22
22Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 23
23Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement?Go to Step 25
24Repair the intermittent condition as necessary. Refer to Connector Repairs and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 25
25Clear 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 26
26Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) ListSystem OK
IMPORTANT
If DTCs P0120 or U0107 is also set, refer to the appropriate DTC for further diagnosis.

DTC P2120

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.

  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.
  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 «Intermittent Conditions»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-troubleshooting__intermittent-conditions) .

The numbers below refer to the steps numbers in the diagnostic table.

  1. 2: This step determines if a communication condition exists.
  2. 5: This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 2 and sensor 3 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a few percent of each other. If the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. If the pedal is fully depressed, all APP angles should be 100 percent.
  3. 6: The APP sensor 1 shares a common 5-volt reference circuit with the throttle position (TP) sensor 1. Monitoring the TP sensor 1 voltage aids in diagnosing the APP sensor 5-volt reference and low reference circuits.
  4. 9: With the TAC module still connected, this test will help determine a short to the signal circuit either within the TAC module or the wiring.
  5. 10: This step determines whether the TAC module or a shorted circuit is causing the condition.
  6. 19: 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.
StepActionValuesYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1Did you perform the Diagnostic System Check-Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2Is DTCs U0107 also set?Go to DTC U0107Go to Step 3
3IMPORTANT: DO NOT depress the accelerator pedal. Start the engine. Observe the DTC information with a scan tool. Did any other throttle actuator control (TAC) module or accelerator pedal position (APP) sensor DTC set except P1125?Go to Diagnostic Trouble Code (DTC) ListGo to Step 4
4Observe the APP sensor Agree/Disagree parameters with a scan tool. Does the scan tool indicate Disagree for any of the APP Agree/Disagree parameters?Go to Step 6Go to Step 5
5Turn ON the ignition, with the engine OFF. Observe the APP sensor angles for both APP sensors with a scan tool. Slowly depress the accelerator pedal, stopping at 25, 50, 75, and 100 percent. Slowly release the accelerator pedal, stopping at 75, 50, 25, and 0 percent. Does the scan tool indicate APP sensor 1 angle within 10.5 percent of the APP sensor 2 angle during the above test?Go to Diagnostic AidsGo to Step 6
6Turn OFF the ignition. Disconnect the APP sensor harness connector. Connect a fused jumper between the APP sensor 1 5-volt reference circuit and ground. Turn ON the ignition, with the engine OFF. Observe the throttle position (TP) sensor 1 voltage parameter with a scan tool. Does the scan tool indicate TP sensor 1 voltage is at the specified value?0.0 VGo to Step 7Go to Step 11
7Connect a fused jumper between the APP sensor 1 5-volt reference circuit and the APP sensor 1 low reference circuit. Observe the TP sensor 1 voltage parameter with a scan tool. Does the scan tool indicate TP sensor 1 voltage is at specified value?0.0 VGo to Step 8Go to Step 12
8Connect a fused jumper between the APP sensor 1 signal circuit and the APP sensor 1 5-volt reference circuit. Observe the APP sensor 1 voltage parameter with a scan tool. Does the scan tool indicate APP sensor 1 voltage is near the specified value?5 VGo to Step 14Go to Step 9
9Test for a short between the APP sensor 1 signal circuit and all other APP circuits at the APP sensor harness connector with a DMM. Does the DMM indicate a short to another circuit?Go to Step 10Go to Step 13
10Turn OFF the ignition. Disconnect both of the TAC module harness connectors. Test for a short between the APP sensor 1 signal circuit and all other APP circuits at the APP sensor harness connector with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 18Go to Step 15
11Turn OFF the ignition. Disconnect the TAC module harness connector containing the APP circuits. Test the APP sensor 1 5-volt reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 18Go to Step 15
12Turn OFF the ignition. Disconnect the TAC module harness connector containing the APP circuits. Test the APP sensor 1 low-reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 18Go to Step 15
13Turn OFF the ignition. Disconnect the TAC module harness connector containing the APP circuits. Test the APP sensor 1 signal circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find an open or high resistance?Go to Step 18Go to Step 15
14Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 18Go to Step 16
15Inspect for poor connections at the harness connectors of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 18Go to Step 17
16Replace the APP sensor assembly. Refer to Accelerator Pedal Position (APP) Sensor Replacement . Did you complete the replacement?Go to Step 18
17Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement?Go to Step 18
18Clear 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 19
19Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) ListSystem OK
IMPORTANT
DO NOT depress the accelerator pedal.

DTC P2121

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.

  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.
  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 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 «Intermittent Conditions»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-troubleshooting__intermittent-conditions) .

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

  1. 2: The throttle position (TP) sensor 2 and the APP sensor 2 share a common 5-volt reference source. Diagnose DTC P0220 first if that DTC is also set.
  2. 6: Measuring the specified voltage at the APP sensor harness connector verifies the integrity of the APP sensor 2 signal circuit from the TAC module.
  3. 18: This test determines whether or not the TAC module can recognize a change in signal voltage.
  4. 19: There are 2 separate 5-volt reference sources within the TAC module. The TP sensor 1 and the APP sensor 1 share one 5-volt reference source. The TP sensor 2 and the APP sensor 2 share another common 5-volt reference source. This test determines whether the signal circuit is shorted to any one of the 5-volt reference circuits. If a short exists, the corresponding sensor voltage will be pulled low.
  5. 20: The previous step found the signal circuit and a 5-volt reference circuit shorted together. This test isolates whether the short is in the harness or within the TAC module.
  6. 26: 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.
StepActionValuesYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1Did you perform the Diagnostic System Check-Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2IMPORTANT: If DTCs P0220 or U0107 is also set, refer to Diagnostic Trouble Code (DTC) List and diagnose the applicable DTC first. Turn ON the ignition, with the engine OFF, and with your foot OFF of the accelerator pedal. Observe the accelerator pedal position (APP) sensor 2 voltage parameter with a scan tool. Does the scan tool indicate the APP sensor 2 voltage is within the specified values?0.24-2.24 VGo to Step 3Go to Step 6
3Fully depress the accelerator pedal to the wide open throttle (WOT) position. Does the scan tool indicate the APP sensor 2 voltage is within the specified values?0.24-4.49 VGo to Step 4Go to Step 6
4Turn OFF the ignition for 15 seconds. Turn ON the ignition, with the engine OFF. Observe the DTC info with a scan tool. Lightly touch and move the related engine wiring harnesses and connectors for the APP sensor while observing the DTC status. If the scan tool indicates this DTC failed this ignition during the above test, repair the intermittent condition as necessary. Refer to Wiring Repairs and Connector Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 5
5Slowly depress the accelerator pedal to WOT, then slowly return the pedal to closed throttle while observing the DTC status. Did the scan tool indicate this DTC failed this ignition during the above test?Go to Step 21Go to Diagnostic Aids
6Disconnect the APP sensor harness connector. Test the APP sensor 2 signal circuit for voltage with a DMM. Does the DMM indicate the APP sensor 2 signal voltage is within the specified values?3.94-6.06 VGo to Step 11Go to Step 7
7Turn OFF the ignition. Disconnect the throttle actuator control (TAC) module harness connector containing the APP sensor circuits. Turn ON the ignition, with the engine OFF. Test the APP sensor 2 signal circuit for a short to voltage with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 8
8Test the APP sensor 2 signal circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 9
9Test the APP sensor 2 signal circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 10
10Test for a short between the APP sensor 2 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 23
11Test the APP sensor 2 5-volt reference circuit for voltage with a DMM. Does the DMM indicate voltage within the specified values?4.54-5.21 VGo to Step 16Go to Step 12
12Turn OFF the ignition. Disconnect the TAC module harness connector containing the APP sensor circuits. Turn ON the ignition, with the engine OFF. Test the APP sensor 2 5-volt reference circuit for a short to voltage with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 13
13Test the APP sensor 2 5-volt reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 14
14Test the APP sensor 2 5-volt reference circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 15
15Test for a short between the APP sensor 2 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 23
16Measure resistance with a DMM connected between the APP sensor 2 low reference circuit and the APP sensor 1 low reference circuit. Does the DMM indicate resistance within the specified values?0-5 ohmGo to Step 18Go to Step 17
17Turn OFF the ignition. Disconnect the TAC module harness connector containing the APP sensor circuits. Test the APP sensor 2 low reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 23
18Connect a fused jumper between the APP sensor 2 signal circuit and the APP sensor 2 low reference circuit at the APP sensor harness connector. Observe the APP sensor 2 voltage parameter with a scan tool. Does the scan tool indicate APP sensor 2 voltage is at the specified value?0 VGo to Step 19Go to Step 23
19Observe the APP sensor 1, the APP sensor 3, and the TP sensor 2 voltage parameters with a scan tool. Connect a fused jumper between the APP sensor 2 signal circuit and the APP sensor 2 low reference circuit at the APP sensor harness connector. Did the scan tool indicate a change in voltage in any of the parameters observed during the above test?Go to Step 20Go to Step 21
20Turn OFF the ignition. Disconnect the TAC module harness connectors. Test for a short between the APP sensor 2 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 23
21Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 22
22Replace the APP sensor assembly. Refer to Accelerator Pedal Position (APP) Sensor Replacement . Did you complete the replacement?Go to Step 25
23Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 25Go to Step 24
24Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement?Go to Step 25
25Clear 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 26
26Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) ListSystem OK
IMPORTANT
If DTCs P0220 or U0107 is also set, refer to Diagnostic Trouble Code (DTC) List and diagnose the applicable DTC first.

DTC P2125

The throttle position (TP) sensors 1 and 2 are potentiometer type sensors, each with the following 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 the TP sensor 2 signals disagree, or signal voltages are outside the predetermined range, this DTC sets.

  1. DTCs 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.
  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 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. If this DTC is determined to be intermittent, refer to «Intermittent Conditions»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-troubleshooting__intermittent-conditions) .

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

  1. 21: 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.
StepActionYesNo
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1Did you perform the Diagnostic System Check - Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2Is DTC U0107 set?Go to Diagnostic Trouble Code (DTC) ListGo to Step 3
3Turn ON the ignition, with the engine OFF. Observe the throttle position (TP) sensor 1 and 2 Agree/Disagree parameter with a scan tool. Does the scan tool TP sensor 1 and 2 Agree/Disagree parameter indicate Disagree?Go to Step 5Go to Step 4
4Remove the air inlet duct from the throttle body. Disconnect the throttle body harness connector. Connect the jumper wires between the TP sensor terminals of the throttle body harness connector and the corresponding TP sensor terminals of the throttle body. Observe the TP sensor 1 and 2 with a scan tool. Slowly open the throttle blade to wide open throttle (WOT) and back to the closed throttle position several times by hand. Does the TP sensor Agree/Disagree parameter change from Agree to Disagree during the above test?Go to Step 18Go to Diagnostic Aids
5Disconnect the TP sensor harness connector. Disconnect the throttle actuator control (TAC) module harness connectors. Test the TP sensor 1 5-volt reference circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 6
6Test for a short between the TP sensor 1 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 7
7Test the TP sensor 1 signal circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 8
8Test for a short between the TP sensor 1 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 9
9Test the TP sensor 1 low reference circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 10
10Test for a short between the TP sensor 1 low reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 11
11Test the TP sensor 2 5-volt reference circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 12
12Test for a short between the TP sensor 2 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 13
13Test the TP sensor 2 signal circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 14
14Test for a short between the TP sensor 2 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 15
15Test the TP sensor 2 low reference circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 16
16Test for a short between the TP sensor 2 low reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 17
17Inspect for an intermittent and for a poor connection at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 18
18Inspect for an intermittent and for a poor connection at the harness connector of the throttle body. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?Go to Step 20Go to Step 19
19Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . 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. Are there any DTCs that have not been diagnosed?Go to Diagnostic Trouble Code (DTC) ListSystem OK

DTC P2135

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.

  1. The ignition switch is in the Crank or Run position.
  2. The ignition voltage is more than 5.23 volts.
  1. Invalid or missing serial data messages are detected.
  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.
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 «Intermittent Conditions»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-troubleshooting__intermittent-conditions) .

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 (PCM) Connector End Views
1Did you perform the Diagnostic System Check-Engine Controls?Go to Step 2Go to Diagnostic System Check - Engine Controls
2Is DTC P0604 also set?Go to DTC P0601-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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. Did you find and correct the condition?Go to Step 23Go to Step 21
20Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement?Go to Step 23
21Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement . Did you complete the replacement?Go to Step 23
22Replace the Junction Block. Refer to Junction Block Replacement - Accessory Wiring in Wiring Systems. 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 System Check - Engine ControlsSystem OK

DTC U0107

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