• | 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 provide an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
---|---|---|---|
Ignition 1 Voltage | P0973, P0976, P2764 | P0973, P0976, P2764 | -- |
1-2 SS Valve Control | P0973 | P0973 | P0974 |
2-3 SS Valve Control | P0976 | P0976 | P0977 |
TCC PWM Valve Control | P2764 | P2764 | P2763 |
Circuit | Normal | Short to Ground | Open/High Resistance | Short to Voltage |
---|---|---|---|---|
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: Indeterminate | ||||
1-2 Sol. CKT Status | Indeterminate | Short to GND | Open | Short to Volts |
2-3 Sol. CKT Status | Indeterminate | Short to GND | Open | Short to Volts |
TCC Duty Cycle CKT Status | Indeterminate | Short to GND | Open | Short to Volts |
The 1-2 SS valve and the 2-3 SS valves control transmission fluid pressure acting on the shift valves to position the valves for the appropriate gear. The 1-2 SS and the 2-3 SS valves are normally-open exhaust valves located on the control valve body. A fused circuit supplies ignition voltage to the 1-2 SS valve and the 2-3 SS valve. The TCM commands the solenoid ON or OFF by switching the ground path. When the 1-2 SS valve or the 2-3 SS valve is commanded ON, the TCM senses low voltage. When the 1-2 SS valve or the 2-3 SS valve is commanded OFF, the TCM senses high voltage.
The torque converter clutch pulse width modulated (TCC PWM) solenoid is a normally closed solenoid used to control the apply and release of the converter clutch. When the vehicle operating conditions are appropriate to apply the TCC, the transmission control module (TCM) immediately increases the duty cycle to approximately 42 percent. The TCM then ramps the duty cycle to approximately 90 percent to achieve full TCC apply pressure. When the TCC is fully applied, the engine is coupled directly to the transmission through the TCC. When the solenoid is commanded OFF, the TCM senses high voltage. When the solenoid is commanded ON, the TCM senses low voltage.
• | The ignition is ON. |
• | The ignition voltage is between 8 and 18-volts |
The TCM detects an open or short to ground on the shift solenoid valve control circuit for 4.4 seconds.
The TCM detects a short to voltage on the shift solenoid valve control circuit for 4.4 seconds.
The TCM detects a short to voltage on the TCC PWM solenoid control circuit for 4.4 seconds
The TCM detects an open or short to ground on the TCC PWM solenoid control circuit for 4.4 seconds.
• | DTC P0973, P0974, P2763, and P2764 are type B DTCs. |
• | DTC P0976 and P0977 are type A DTCs. |
• | DTC P0973, P0974, P2763, and P2764 are type B DTCs. |
• | DTC P0976 and P0977 are type A DTCs. |
Automatic Transmission Controls Schematics
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
• | J 35616 GM Terminal Test Kit |
• | J 44152 Jumper Harness (20 Pins) |
Start and idle the engine. Using the scan tool output controls, command the affected solenoid ON and OFF. Observing the CKT Status parameter on the scan tool, ensure the parameter shows OK.
⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the fuse is open, test or replace the affected solenoid. |
• | Terminals E and A for SS valve 1-2. |
• | Terminals E and B for SS valve 2-3. |
• | Terminals E and S for the TCC solenoid. |
⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the TCM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the TCM. |
• | Terminals E and A for SS valve 1-2. |
• | Terminals E and B for SS valve 2-3. |
⇒ | If not within the specified range, test the internal transmission wiring harness for an open or high resistance. If the circuits test normal, replace the affected shift solenoid valve. |
⇒ | If not the specified value, test the internal transmission wiring harness for a short to ground. If the circuits test normal, replace the affected shift solenoid valve. |
⇒ | If not within the specified range, test the internal transmission wiring harness for an open or high resistance. If the circuits test normal, replace the TCC solenoid. |
⇒ | If not the specified value, test the internal transmission wiring harness for a short to ground. If the circuits test normal, replace the TCC solenoid valve. |
Perform the Diagnostic Repair Verification after completing the repair.
Valve Body and Pressure Switch Replacement .
Control Module References for TCM replacement, setup and reprogramming.