For 1990-2009 cars

### Diagnostic Instructions

• | 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.

### DTC Descriptors

DTC P0973: 1-2 Shift Solenoid (SS) Control Circuit Low Voltage
DTC P0974: 1-2 Shift Solenoid (SS) Control Circuit High Voltage

### Diagnostic Fault Information

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

### Typical Scan Tool Data

#### 1-2 Shift Solenoid (SS) Control Circuit Parameter Data

Circuit | Normal | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | --- | ---
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: OK
1-2 Sol. CKT Status | OK | Open/Short to GND | Open/Short to GND | Short to Volts
2-3 Sol. CKT Status | OK | Open/Short to GND | Open/Short to GND | Short to Volts
TCC Duty Cycle CKT Status | OK | Open/Short to GND | Open/Short to GND | Short to Volts

### Circuit/System Description

The 1-2 shift solenoid (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 transmission control module (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.

### Conditions for Running the DTC

The engine speed is greater than 500 RPM for 2 seconds.

### Conditions for Setting the DTC

#### P0973

The TCM detects an open or short to ground on the 1-2 SS valve control circuit for 4.4 seconds.

#### P0974

The TCM detects a short to voltage on the 1-2 SS valve control circuit for 4.4 seconds.

### Action Taken When the DTC Sets

#### P0973

• | DTC P0973 is a Type B DTC.

• | The TCM inhibits 3-2 downshifts when the vehicle speed is greater than 52 km/h (32 mph).

• | The TCM commands maximum line pressure.

• | The TCM freezes transmission adaptive functions.

#### P0974

• | DTC P0974 is a Type B DTC.

• | The TCM commands maximum line pressure.

• | The TCM freezes transmission adaptive functions.

### Conditions for Clearing the DTC

DTCs P0973 and P0974 are Type B DTCs.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Electronic Component Description for Shift Solenoid Valves 1-2 and 2-3 information

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 44152 Jumper Harness (20 pins)

### Circuit/System Verification

1. Ignition ON, engine OFF, observe the 1-2 Sol. CKT Status parameter while commanding the 1-2 SS ON and OFF with a scan tool. The reading should display OK or Indeterminate.
2. 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 data.

### Circuit/System Testing

Important: Additional DTCs may set when disconnecting the automatic transmission inline 20-way connector.

1. Ignition OFF, disconnect the automatic transmission (AT) inline 20-way connector at the transmission.
2. Install the J 44152 on the engine side of the AT inline 20-way connector.
3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal E and ground.

⇒ | 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 ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.

4. Connect a test lamp between the control circuit terminal A and the ignition circuit terminal E.
5. Command the 1-2 SS ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | 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.

6. If all circuits test normal, test the internal transmission wiring harness assembly and the 1-2 shift solenoid.

### Component Testing

1. Ignition OFF, disconnect the automatic transmission (AT) inline 20-way connector at the transmission.
2. Install the J 44152 on the transmission side of the AT inline 20-way connector.
3. Test for 19-31 ohms of resistance between the control terminal A and the ignition terminal E of the transmission.

⇒ | If not within the specified range, test the circuits for a short to ground or an open/high resistance. If a circuit is shorted or open replace the internal transmission wiring harness assembly, if the circuits test normal, replace the 1-2 shift solenoid.

4. Test for infinite resistance between each terminal and the transmission housing/case.

⇒ | If not the specified value, test the circuits for a short to ground or an open/high resistance. If a circuit is shorted replace the internal transmission wiring harness assembly, if the circuits test normal, replace the 1-2 shift solenoid.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• | Wiring Harness Replacement

• | 1-2 Shift Solenoid Valve Replacement

• | Control Module References for TCM replacement, setup, and reprogramming