Diagnostic Starting Point - Automatic Transmission
Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check provides the following information
- The identification of the control module or modules which commands the system
- The ability of the control module or modules to communicate through the serial data circuit
- The identification and status of stored diagnostic trouble codes (DTCs)
The use of Diagnostic System Check - Vehicle in Vehicle DTC Information identifies the correct procedure for diagnosing the system and the procedure location.
Symptoms
When it has been determined through Diagnostic System Check - Vehicle in Vehicle DTC Information that no DTCs are present, begin symptom diagnosis by reviewing the Transmission Component and System Description . Reviewing the Transmission Component and System Description information enables you to understand the operation of the system. This helps you determine if the condition described by the customer is normal or if a malfunction exists. If it is determined that a malfunction exists, identify the concern by referring to Symptoms - Automatic Transmission . The Symptoms - Automatic Transmission table provides common diagnostic categories which relate directly to diagnostic information or procedures.
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| 1-2 Solenoid | The transmission control module (TCM) commands the 1-2 shift solenoid valve ON and OFF. The scan tool 1-2 Sol. parameter should match the commanded state. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to Shift Solenoid Valve State and Gear Ratio . When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. When the engine is running, the following control limits apply: Only sequential gear changes are allowed. For example, 1st to 3rd is not allowed. If a non-sequential gear change is attempted, the message "Non-sequential gear changes not allowed. Gear changes must be in order" appears on the scan tool display. The vehicle speed must be below a calibrated value. If the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The engine speed must be below a calibrated value. If the engine speed is too high, the message "Engine speed too high" appears on the scan tool display. Downshifts are allowed only when the vehicle speed is below a calibrated value. If the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for 3-2 or 2-1 downshift" appears on the scan tool display. The gear requested may not be greater than the current selected transmission range, PRNDL. For example, 3rd gear is not allowed if the transmission range is D2. If the gear requested is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. | |
| 2-3 Solenoid | The TCM commands the 2-3 shift solenoid valve ON and OFF. The scan tool 2-3 Sol. parameter should match the commanded state. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to Shift Solenoid Valve State and Gear Ratio . When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid will remain ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. When the engine is running, the following control limits apply: Only sequential gear changes are allowed. For example, 1st to 3rd is not allowed. If a non-sequential gear change is attempted, the message "Non-sequential gear changes not allowed. Gear changes must be in order" appears on the scan tool display. The vehicle speed must be below a calibrated value. If the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The engine speed must be below a calibrated value. If the engine speed is too high, the message "Engine speed too high" appears on the scan tool display. Downshifts are allowed only when the vehicle speed is below a calibrated value. If the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for 3-2 or 2-1 downshift" appears on the scan tool display. The gear requested may not be greater than the current selected transmission range, PRNDL. For example, 3rd gear is not allowed if the transmission range is D2. If the gear requested is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. | |
| Reset Transmission Adapts | The TCM clears, or resets, the TAP cells to the original base value. There are no limits to using this output control. It may be performed with the engine running or when the ignition is ON, and the engine is OFF. | |
| PC Solenoid | The TCM commands the amperage, current, to the pressure control solenoid in order to control transmission line pressure. As the amperage increases, the line pressure decreases. As the amperage decreases, the line pressure increases. The amperage range is 0.00-1.10 and may be commanded in one-tenth amp increments. When the ignition is ON, and the engine is OFF, the reference, commanded, amperage may be controlled within calibrated limits. The scan tool parameter "PC Sol. Ref. Current" changes, but the parameter "PC Sol. Actual Current" does not change. The reference current remains until commanded otherwise. When the engine is running, the following control limits apply: When the transmission range is Park or Neutral, the reference, commanded, amperage may be controlled within calibrated limits. The engine speed must be less than 1,500 RPM. If the engine speed is greater than 1,500 RPM, the message "TR in park/neutral and engine speed over 1,500 RPM" appears on the scan tool display. Both the scan tool parameters "PC Sol. Ref. Current" and "PC Sol. Actual Current" change. Both current readings remain until commanded otherwise. When the transmission range is not in Park or Neutral, the reference amperage can only be controlled less than the current determined by the TCM. The TCM does not allow a value to be selected that may cause damage to the transmission. If the requested amperage is more than allowed by the TCM, the message "Requested current for the PC Solenoid is too high" appears on the scan tool display. Transmission range DTCs must not be active. If a transmission range DTC is active, the message "Engine running with transmission DTC present" appears on the scan tool display. | |
| Shift Transmission | The TCM commands upshifts and downshifts. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to Shift Solenoid Valve State and Gear Ratio . When the ignition is ON, and the engine is OFF, there are no limits to this control. The scan tool shift solenoid states change to match the Commanded Gear selected. When the engine is running, the following control limits apply: The TCM does not allow a shift if it causes the engine RPM to exceed a calibrated limit. If a gear is requested and the engine speed is too high, the message "Engine speed too high" appears on the scan tool display. The TCM does not allow a 3-2 or 2-1 downshift if the vehicle speed exceeds a calibrated limit. If either downshift is requested and the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for 3-2 or 2-1 downshift" appears on the scan tool display. The TCM does not allow a 4-3 downshift if the vehicle speed exceeds a calibrated limit. If a 4-3 downshift is requested and the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The TCM does not allow an upshift if the vehicle speed exceeds a calibrated limit. If an upshift is requested and the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The TCM does not allow an upshift that is greater than the current selected transmission range, PRNDL. For example 3rd gear is not allowed if the transmission range is D2. If an upshift is requested that is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display. | |
| TCC Control Solenoid | The TCM commands the duty cycle of the TCC PWM solenoid. The duty cycle is represented by a percentage of ON, energized, time. Approximately 90-100 percent duty cycle represents an ON, energized, commanded state. Zero percent represents an OFF, non-energized, commanded state. The scan tool TCC Duty Cycle parameter should match the commanded state. When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains ON, 90-100 percent duty cycle, until commanded OFF, zero percent duty cycle, and vice versa. When the output control is exited, the solenoid duty cycle is determined by the TCM. When the engine is running, the following control limits apply: If the transmission range is Park, and the transmission is in hot mode, the TCC control solenoid may not be commanded OFF. If the solenoid is requested OFF, the message "TCC OFF command disabled in Hot Mode" appears on the scan tool display. The TCC control solenoid may not be commanded OFF for more than a calibrated amount of time. If the solenoid is commanded OFF, for a certain amount of time, the message "TCC OFF time has been exceeded" appears on the scan tool display. |
Scan Tool Output Controls
Scan Tool Data List
Use the scan tool data values under the following conditions
- The «Diagnostic System Check - Vehicle»(/chevrolet/cobalt/i-2004-2010/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information is complete.
- The On-Board Diagnostics are functioning properly.
- There are no diagnostic trouble codes (DTCs) present.
The values below represent a typical display recorded from a properly functioning system.
| IMPORTANT | Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts. |
Only the parameters listed below are used in this manual for diagnosing. If a scan tool displays other parameters, the values are not recommended by General Motors for use in diagnosis.
Scan tool values below were recorded under the following conditions
- Engine at idle
- Upper radiator hose hot
- Closed throttle
- Transmission in Park
- Closed Loop operation
- Accessories OFF
- Brake pedal not applied
| Scan Tool Parameter | Data List* | Units Displayed | Typical Data Value |
|---|---|---|---|
| 1-2 Shift Time | F0, F2, F6/F0 | Seconds | Varies |
| 1-2 Sol. | F0, F2, F3, F4 | On/Off | On |
| 1-2 Sol. CKT Status | F2 | OK, Open/Short to GND, Short to Volts | OK |
| 1-2 TAP Cell 4-16 | F6/F0 | KPa (psi) | Varies |
| 2-3 Shift Time | F0, F3, F6/F1 | Seconds | Varies |
| 2-3 Sol. | F0, F2, F3, F4 | On/Off | Off |
| 2-3 Sol. CKT Status | F3 | OK, Open/Short to GND, Short to Volts | OK |
| 2-3 TAP Cell 4-16 | F6/F1 | KPa (psi) | Varies |
| 3-4 Shift Time | F0, F4, F6/F2 | Seconds | Varies |
| 3-4 TAP Cell 4-16 | F6/F2 | KPa (psi) | Varies |
| Calc. Throttle Position | F0, F1, F2, F3, F4, F5 | % | 0% |
| Commanded Gear | F0, F1, F2, F3, F4, F5 | 1, 2, 3, 4 | 1 |
| Current TAP Cell | F6/F0, F6/F1, F6/F2 | 4-16 | Varies |
| ECT Sensor | F0, F1 | °C (°F) | 85-105°C (185-220°F) |
| Engine Speed | F0, F1, F2, F3, F4, F5 | RPM | Varies |
| Engine Torque | F0, F1 | N.m (lb ft) | Varies |
| Gear Ratio | F0, F1, F2, F3, F4 | Ratio | 3.98:1 |
| Ignition Voltage | F0 | Volts | 12.6-14.7 |
| Last Shift Time | F0 | Seconds | Varies |
| PC Sol. Actual Current | F0, F5 | Amps | Varies |
| PC Solenoid Duty Cycle | F0, F5 | % | Varies |
| PC Sol. Ref. Current | F0, F5 | Amps | Varies |
| Steady State TAP 1GR | F6/F3 | KPa (psi) | Varies |
| Steady State TAP 2GR | F6/F3 | KPa (psi) | Varies |
| Steady State TAP 2GR/TCC | F6/F3 | KPa (psi) | Varies |
| Steady State TAP 3GR | F6/F3 | KPa (psi) | Varies |
| Steady State TAP 3GR/TCC | F6/F3 | KPa (psi) | Varies |
| Steady State TAP 4GR | F6/F3 | KPa (psi) | Varies |
| Steady State TAP 4GR/TCC | F6/F3 | KPa (psi) | Varies |
| Steady State TAP Reverse | F6/F3 | KPa (psi) | Varies |
| TCC Brake Switch | F0, F1 | Open/Closed | Closed |
| TCC Duty Cycle | F0, F1 | % | 0% |
| TCC Duty Cycle CKT Status | F1 | OK, Open/Short to GND, Short to Volts | OK |
| TCC Release Pressure | F0, F1 | Yes/No | Yes |
| TCC Slip Speed | F0, F1 | RPM | Varies |
| TFP Sw. | F0 | Park/Neutral, Reverse, Drive, or invalid | Park/Neutral |
| TFP Sw. Sig. B/ Sig. C | F0 | HI/LOW | HI/HI |
| TR Sw. | F0 | Park, Reverse, Neutral, Drive 4, Drive 3, Drive 2, Drive 1 or invalid | Park |
| TR Sw. A/B/C/P | F0 | HI/LOW | LOW/HI/HI/LOW |
| Traction Control Signal | F0 | Active/Inactive | Inactive |
| Trans. Fluid Temp. | F0, F1, F5 | °C (°F) | 80-90°C (176-194°F) |
| Transmission Hot Mode | F0, F1 | On/Off | Off |
| Transmission ISS | F0, F1, F2, F3, F4 | RPM | Varies |
| Transmission OSS | F0, F1, F2, F3, F4 | RPM | 0 |
| Vehicle Speed | F0, F1, F2, F3, F4 | Km/h (mph) | 0 |
| *Data List Legend F0: Transmission Data F1: TCC Data F2: 1-2 Shift Data F3: 2-3 Shift Data F4: 3-4 Shift Data F5: PC Solenoid Data F6/F0: Transmission Adapts/1-2 Adapt. Data F6/F1: Transmission Adapts/2-3 Adapt. Data F6/F2: Transmission Adapts/3-4 Adapt. Data F6/F3: Transmission Adapts/Steady State Data | |||
Scan Tool Data List
Diagnostic Trouble Code (DTC) Type Definitions
The DTC Type Definitions contain the characteristics for all types of DTCs. Each DTC type may or may not be found in this section. The DTC type is based on the action that the TCM takes when storing DTC information, and whether or not the TCM illuminates a service lamp or displays a message on a driver information center (DIC). The DTC descriptions in the Diagnostic Trouble Code List/Type below are listed in numeric order and indicate the DTC types for domestic and export vehicle applications. Each DTC is categorized into one of the following types
Type A
This DTC is emissions related. The TCM stores the DTC in History, Freeze Frame and Failure Records during the first trip in which the conditions for setting the DTC are met. The TCM also illuminates the malfunction indicator lamp (MIL) during the first trip in which the conditions for setting the DTC are met.
Type B
This DTC is emissions related. The TCM stores the DTC in Failure Records during the first trip in which the conditions for setting the DTC are met. The TCM stores the DTC in History and Freeze Frame during the second consecutive trip in which the conditions for setting the DTC are met. The TCM also illuminates the MIL during the second consecutive trip in which the conditions for setting the DTC are met.
Type C
This DTC is non-emissions related. The TCM stores the DTC in History and Failure Records during the first trip in which the conditions for setting the DTC are met. The TCM does not store the DTC in Freeze Frame and does not illuminate the MIL. For some type C DTCs, a message may be displayed on a DIC, if equipped. For other type C DTCs, a separate service lamp, other than the MIL, may be illuminated. Type C DTCs that do not display a message on the DIC or illuminate a separate service lamp were formerly referred to as type D.
Type X
This DTC is available in the TCM software, but has been disabled, or turned off. In this case, the diagnostic does not run, DTCs are not stored, and the MIL does not illuminate. Type X DTCs are used primarily for export vehicles that do not require MIL illumination or DTC storing.
The service information contained in this manual refers to the domestic, federal, calibration package. Domestic calibrations apply to vehicles sold in the United States, Canada and Japan. Export calibrations exist for both leaded and unleaded vehicles. DTC types may change for some export vehicles, and some DTCs may be turned off for leaded export vehicles. Differences between domestic and export calibrations are not reflected on DTC support information pages. DTC types for export calibrations are referenced only in the Diagnostic Trouble Code List/Type.
Diagnostic Trouble Code (DTC) List/Type
| DTC Description | DTC Type |
|---|---|
| DTC P0218 | C |
| DTC P0562 | C |
| DTC P0563 | C |
| DTC P0601, P0602, P0603, or P0604 | A |
| DTC P0705 | C |
| DTC P0711 | C |
| DTC P0712 | C |
| DTC P0713 | C |
| DTC P0716 | B |
| DTC P0717 | B |
| DTC P0719 | C |
| DTC P0722 | B |
| DTC P0723 | B |
| DTC P0724 | C |
| DTC P0741 | B |
| DTC P0742 | B |
| DTC P0751 | B |
| DTC P0752 | B |
| DTC P0756 | A |
| DTC P0757 | A |
| DTC P0842 | B |
| DTC P0843 | B |
| DTC P0961 | C |
| DTC P0973 | B |
| DTC P0974 | B |
| DTC P0976 | A |
| DTC P0977 | A |
| DTC P1621 | A |
| DTC P1810 | B |
| DTC P1811 | C |
| DTC P1816 | B |
| DTC P1818 | B |
| DTC P2763 | B |
| DTC P2764 | B |
| DTC U2100 in Computer/Integrating Systems | B |
| DTC U2105 refer to DTC U2105-U2199 in Computer/Integrating Systems | B |
| DTC U2107 refer to DTC U2105-U2199 in Computer/Integrating Systems | C |
| DTC U2108 refer to DTC U2105-U2199 in Computer/Integrating Systems | C |
Diagnostic Trouble Code (DTC) List/Type