GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2009 🢒 Vibe - AWD 🢒 DTC 🢒 DTC P0778

Circuit Description

Shifting from 1st to 4th (O/D) is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1 and SL2 which is controlled by the engine control module (ECM). If an open or short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be operated smoothly (fail safe function). The ECM will illuminate the MIL and store the DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0778 Pressure Control Solenoid "B" Electrical (Shift Solenoid Valve SL2)

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The ECM detects an open or short in the shift solenoid valve SL2 circuit.

Action Taken When the DTC Sets
    • DTC P0778 is a type C DTC.
    • The malfunction indicator lamp (MIL) illuminates the first time the diagnostic runs with the fault active.

Conditions for Clearing the MIL/DTC

The DTC will clear when conditions for setting the DTC have been repaired.

Step

Action

Values

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn the ignition to OFF.
  2. Disconnect the transmission connector E1.
  3. Measure the resistance as follows:
    4. • Between connector E1 terminals 4 and 9
    • Between connector E1 terminal 4 and body ground
    • Between connector E1 terminal 9 and body ground

Is the resistance measured within specified value?

Between terminals  4 and 9 = 5 to 5.6 Ohms

Between terminal 4 and body ground = 10 Kohms or higher

Between terminal 9 and body ground = 10 Kohms or higher

Go to Step 3

Go to Step 4

3
  1. Connect the transmission connector E1.
  2. Disconnect the ECM connectors.
  3. Measure the resistance as follows:
    4. • Between connector E7 terminal 14 and terminal 15
    • Between connector E7 terminal 14 and body ground
    • Between connector E7 terminal 15 and body ground

Is the resistance measured within specified value?

Between terminals 14 and 15 = 5 to 5.6 Ohms

Between E7 terminal 14 and body ground = 10 Kohms or higher

Between E7 terminal 15 and body ground = 10 Kohms or higher

Go to Step 8

Go to Step 5

4
  1. Turn the ignition to OFF.
  2. Remove the shift solenoid valve SL2.
  3. Measure the resistance between terminals 1 and 2 of the solenoid valve connector.
  4. Connect the positive lead with a 21 watt bulb to terminal 2 and the negative lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.

Is the resistance measured within specified value and does the solenoid make an operating sound?

5 to 5.6 Ohms

Go to Step 6

Go to Step 7

5

Repair or replace harness or connector of the ECM. Refer to Wiring Repairs and Connector Repairs.

Did you complete the repair or replacement?

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Go to Step 9

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6

Repair or replace harness or connector of the shift solenoid valve SL2. Refer to Wiring Repairs and Connector Repairs.

Did you complete the repair or replacement?

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Go to Step 9

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7

Replace the shift solenoid valve SL2.

Did you complete the replacement?

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Go to Step 9

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8

Replace the ECM. Refer to Control Module References.

Did you complete the replacement?

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Go to Step 9

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9
  1. Use the scan tool in order to clear the DTC.
  2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

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Go to Step 2

System OK