• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
APP Sensor 1 Signal | P2122 | P2122 | P2123 | -- |
APP Sensor 1 5-Volt Reference | P0651 | P2122 | P0651 | -- |
APP Sensor 1 Low Reference | -- | P2123 | -- | -- |
APP Sensor 2 Signal | P2127 | P2127 | P2128 | -- |
APP Sensor 2 5-Volt Reference | P0641, P0452, P0532, P0522 | P2127 | P0641, P0108, P0533, P0522 | -- |
APP Sensor 2 Low Reference | -- | P2128 | -- | -- |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: The engine is operating at idle Parameter Normal Range APP Sensor 1: 0.33-4.59 V | |||
5-Volt Reference 1 | 0 V | 0 V | 5 V |
APP Sensor 1 Signal | 0 V | 0 V | 5 V |
APP Sensor 1 Low Reference | -- | 4.96 V | -- |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: The engine is operating at idle Parameter Normal Range APP Sensor 2: 0.16-2.30 V | |||
5-Volt Reference 2 | 0 V | 0 V | 5 V |
APP Sensor 2 Signal | 0 V | 0 V | 5 V |
APP Sensor 2 Low Reference | -- | 4.92 V | -- |
The throttle actuator control (TAC) system uses two accelerator pedal position (APP) sensors to monitor the accelerator pedal position. The APP sensors 1 and 2 are located within the pedal assembly. Each sensor has the following circuits:
• | A 5-volt reference circuit |
• | A low reference circuit |
• | A signal circuit |
Two processors are also used to monitor the TAC system data. Both processors are located within the engine control module (ECM). Each signal circuit provides both processors with a signal voltage proportional to pedal movement. The processors share and monitor data to verify that the indicated APP calculation is correct.
• | The system voltage is more than 5.23 volts. |
• | The ignition is in the Unlock/Accessory, Run, or Crank position. |
• | DTC P0641, P0651, or P0606 is not set. |
• | The DTCs run continuously when the above conditions are met. |
• | The system voltage is more than 5.23 volts. |
• | The ignition is in the Unlock/Accessory or Run position. |
• | DTC P0641, P0651, P0606, P2120, P2122, P2123, P2125, P2127, or P2128 is not set. |
• | The DTC runs continuously when the above conditions are met. |
The ECM detects that APP sensor 1 voltage is less than 0.33 volt or more than 4.59 volts for more than 0.5 second.
The ECM detects that APP sensor 1 voltage is less than 0.33 volt for more than 0.5 second.
The ECM detects that APP sensor 1 voltage is more than 4.59 volts for more than 0.5 second.
The ECM detects that APP sensor 2 voltage is less than 0.16 volt or more than 2.30 volts for more than 0.5 second.
The ECM detects that APP sensor 2 voltage is less than 0.16 volt for more than 0.5 second.
The ECM detects that APP sensor 2 voltage is more than 2.30 volts for more than 0.5 second.
The ECM detects that the difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than 0.5 second.
• | DTCs P2120, P2122, P2123, P2125, P2127, P2128, and P2138 are Type A DTCs. |
• | The control module commands the TAC system to operate in Reduced Engine Power mode. |
DTCs P2120, P2122, P2123, P2125, P2127, P2128, and P2138 are Type A DTCs.
Throttle Actuator Control (TAC) System Description
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
⇒ | If DTC P2120 or P2125 are the only DTCs set, replace the control module. |
⇒ | If DTC P0641 or P0651 are set, refer to DTC P0641 or P0651 . |
⇒ | If greater than 3 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If less than 4.8 volts, test affected 5-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If greater than 5.2 volts, test affected 5-volt reference circuit for short to voltage. If the circuit tests normal, replace the ECM. |
⇒ | If greater than 0.1 volts, test the APP sensor 1 and 2 signal circuits terminals B and E for a short to voltage. If the circuit tests normal, replace the ECM. |
⇒ | If less than 4.8 volts, test the APP sensor 1 signal circuit for an open or short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If less than 4.8 volts, test the APP sensor 2 signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the control module. |
• | ECM C1 low reference circuit terminal 23 to APP terminal A |
• | ECM C1 low reference circuit terminal 30 to APP terminal D |
• | ECM C1 signal circuit terminal 29 to APP terminal E |
• | ECM C1 signal circuit terminal 32 to APP terminal B |
• | ECM C1 5-volt reference circuit terminal 36 to terminal C |
• | ECM C1 5-volt reference circuit terminal 56 to terminal F |
⇒ | If greater than 5 ohms, repair the affected circuit. |
⇒ | If less than infinite resistance, repair the short between APP sensor 1 signal circuit and APP sensor 2 signal circuits. |
⇒ | If all circuits test normal, replace the accelerator pedal. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |