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 Descriptor

DTC P2670: Solenoid High Control Circuit Group 2 Low Voltage
DTC P2671: Solenoid High Control Circuit Group 2 High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | ---
High Side Driver 2 | P2670 | P2670 | P2671

### Circuit/System Description

The transmission control module (TCM) provides voltage to the pressure control solenoid, the shift solenoids, and the torque converter clutch pulse width modulated (TCC PWM) solenoid through two separate solid-state devices called high side drivers, called HSD1 and HSD2. HSD1 provides electrical power to the pressure control solenoid. HSD2 provides power to the shift solenoids. A normal function of the TCM is to run tests on each driver to ensure that it is functioning properly.

### Conditions for Running the DTC

#### P2670

The engine run time is greater than 5 seconds.

#### P2671

The ignition is ON.

### Conditions for Setting the DTC

#### P2670

The TCM detects a short to ground on the HSD2 circuit when the HSD2 is commanded ON.

#### P2671

The TCM detects greater than 6.4 volts at the HSD2 terminal prior to commanding the HSD2 ON.

### Action Taken When the DTC Sets

• | DTC P2670 and P2671 are Type B DTCs.

• | The TCM turns off power to all solenoids.

• | The transmission will operate in fifth gear if the vehicle has successfully completed a 1-2 upshift in the current ignition cycle. If the vehicle has not completed a 1-2 upshift in the current ignition cycle, the transmission will operate in fourth gear.

• | The TCM commands maximum line pressure.

• | The TCM freezes transmission adaptive functions.

• | The TCC is disabled.

### Conditions for Clearing the DTC

DTC P2670 and P2671 are Type B DTCs.

### Diagnostic Aids

1. P2670 and P2671 only sets on the High Side Driver 2 side of the shift solenoids. Electrical faults on the ground side of the shift solenoids will set the shift solenoids code for that circuit.
2. An open on the High Side Driver 2 side of the shift solenoids will set one or more of the shift solenoid codes.
3. When a code is set, the TCM turns OFF power to HSD2.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Transmission General Description

#### 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

Transmission Control Module Scan Tool Information

#### Special Tools

• | J 35616 GM Terminal Test Kit

• | J 45681 Jumper Harness

### Circuit/System Verification

Ignition ON, engine OFF. With a scan tool, observe the High Side Driver 2 parameter status for:

• | Short to Ground

• | Open

• | Short to Volts

### Circuit/System Testing

1. Ignition OFF, disconnect the X101 harness connector.
2. Install the J 45681 harness on the transmission pass-thru connector.
3. Using the brown J35616-6 test probes from the most current J 35616 kit , test the resistance for the following: 1-2 Shift Solenoid Valve, 2-3 Shift Solenoid Valve, 4-5 Shift Solenoid Valve, TCC PWM Solenoid Valve. Refer to Component Resistance.

⇒ | If less than the specified value, test the affected circuits for a short together condition. If circuits test normal, replace the affected solenoid.

⇒ | If greater than the specified value, test the affected circuits for an open. If circuits test normal, replace the affected solenoid.

4. Test for greater than 10 K ohms between the solenoid supply voltage circuit, terminal 17, and all other circuits of the J 45681 harness , except:

• | 1-2 Shift Solenoid Valve Control circuit, pin 14

• | 2-3 Shift Solenoid Valve Control circuit, pin 9

• | 4-5 Shift Solenoid Valve Control circuit, pin 5

• | TCC PWM Solenoid Valve Control circuit, pin 20

⇒ | If less than the specified value, the affected circuits are shorted together. Replace the transmission internal wire harness.

5. Test for greater than 50 K ohms between the solenoid supply voltage circuit, terminal 17, and the transmission case.

⇒ | If less than the specified value, test the following circuits and solenoids for short to the transmission case.

• | 1-2 Shift Solenoid Valve Control circuit, pin 14

• | 2-3 Shift Solenoid Valve Control circuit, pin 9

• | 4-5 Shift Solenoid Valve Control circuit, pin 5

• | TCC PWM Solenoid Valve Control circuit, pin 20

6. Remove the J 45681 harness from the transmission pass-thru connector and install it on the engine side of the X101.
7. Key ON, engine OFF. Using the brown J35616-7 test probes from the most current J 35616 kit , test for greater than 50 K ohms between the solenoid supply voltage circuit, terminal 17, and the transmission case.

⇒ | If less than the specified value, test the solenoid supply voltage circuit for a short to the transmission case. If circuits test normal, replace the TCM.

8. Disconnect the X1 harness connector at the TCM.

Note: When test probing the TCM harness terminals; it is imperative to use the proper test probe from the most current version of the J 35616 kit . Use the light blue J35616-64B probes.

9. Using a 5A fused jumper wire and the light blue probes J35616-64B, test for greater than 10 K ohms between the solenoid supply voltage circuit, terminal F8, and all other circuits of the X1.

⇒ | If less than the specified value, the affected circuits are shorted together.

10. If all circuits and connections test normal, replace the TCM.

### Component Testing

1. Ignition OFF, disconnect the X101 harness connector. Install the J 45681 harness on the transmission pass-thru connector.
2. Using the brown J35616-4 test probes form the most current J 35616 kit , test the following: 1-2 Shift Solenoid Valve, 2-3 Shift Solenoid Valve, 4-5 Shift Solenoid Valve, TCC PWM Solenoid Valve. Refer to Component Resistance.

⇒ | If less than the specified value, test the affected circuits for a short together. If the circuits test normal, replace the affected solenoid.

⇒ | If greater than the specified value, test the affected circuits for an open. If circuits test normal, replace the affected solenoid.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | 1-2 Shift Solenoid Valve Replacement

• | 2-3 Shift Solenoid Valve Replacement

• | 4-5 Shift Solenoid Valve Replacement

• | Torque Converter Clutch Solenoid Replacement

• | Transmission Internal Electrical Harness Replacement

• | Component Resistance

• | Refer to Control Module References for replacement, setup and reprogramming.