GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2007 🢒 Wave 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0787

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0787 Timing Solenoid (ST) Electrical (Ground Short)

Conditions for Setting the DTC
    • No emergency mode.
    • TCM detects that the OFF signal of the timing solenoid (ST) monitor, when the ST driver outputs the ON signal for 0.1 of a second continuously.
    • Detection continuously occurs 3 times or more.

Action Taken When the DTC Sets
    • The TCM will request the illumination of malfunction indicator lamp (MIL) and store the DTC when the TCM detects a failure on the first ignition cycle.
    • After failure detection the emergency mode is enabled.

Conditions for Clearing the DTC
    • The TCM turns OFF the MIL when no further failures are detected on the next 3 consecutive ignition cycles.
    • The scan tool can clear the DTC from the TCM history.
    • The TCM clears the DTC from the TCM history memory after 40 consecutive ignition cycles without fault.
    • The TCM detects the ON signal of the ST monitor for 100 milliseconds.

Cause of Failure
    • The wiring harness or the connector between the Timing Solenoid (ST) and the TCM
    • The Timing Solenoid
    • The TCM

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Automatic Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2
  1. Turn OFF the ignition.
  2. Install the scan tool.
  3. With the engine OFF, turn the ignition switch to the ON position.
  4. Select Store Freeze Frame/Failure Records from the DTC Information menu.
  5. Store Freeze Frame/Failure Records.
  6. Select Clear DTC Information from the DTC Information menu.
  7. Clear the DTC information.
  8. Perform 2 vehicle drive cycles.

Is the malfunction indicator lamp (MIL) ON?

--

Go to Step 3

Go to Step 5

3
  1. Select Request DTC by Status from the DTC Information menu.
  2. Request DTC by Status.

Is DTC P0787 displayed?

--

Go to Step 4

Go to Step 5

4
  1. Turn OFF the ignition.
  2. Measure the resistance between the vehicle harness and timing solenoid sensor.
  3. Disconnect the transmission control module (TCM) connector (X-1) and measure the resistance between terminal A24 and A23.

Is the measurement within the specified values?

20°C (68°F)

11-16Ω

Go to Step 6

Go to Step 7

5

Repair the temporary connection failure of the connector. Refer to Wiring Harness and Connector Inspection Diagnosis .

Did you complete the repair?

--

System OK

--

6
  1. Inspect for damage between the vehicle wiring harness connector and the TCM.
  2. Inspect the connector. Refer to Wiring Harness and Connector Inspection Diagnosis .
  3. Inspect the connection condition between the connector.

Is the connection condition OK?

--

Go to Step 8

Go to Step 5

7
  1. Inspect for damage between the vehicle harness and the Timing Solenoid.
  2. Disconnect the transaxle harness connector of the T/M wiring harness and inspect the resistance between the ST sensor connector terminal 2 and Ground.

Is the measurement within the specified values?

20°C (68°F)

11-16Ω

Go to Step 9

Go to Step 10

8
  1. Replace the TCM. Refer to Transmission Control Module Replacement .
  2. Perform the reproducing test under user condition after confirming no DTC.

Is a DTC displayed?

--

Go to Step 2

System OK

9
  1. Inspect for damage of the vehicle wiring harness or between the connectors.
  2. Test the continuity and short circuit for the vehicle wiring harness and inspect the connection condition between the transaxle harness connectors. Refer to Wiring Harness and Connector Inspection Diagnosis .

Is the condition OK?

--

System OK

Go to Step 5

10
  1. Inspect for damage of the transmission harness connector wire or between the connector of the solenoid.
  2. Inspect the solenoid for damage.

Is the condition found?

--

Go to Step 12

Go to Step 11

11
  1. Inspect for damage of the transmission harness connector.
  2. Test the continuity and short circuit for the transmission harness connector and inspect the connection condition between connectors. Refer to Wiring Harness and Connector Inspection Diagnosis .

Is the condition OK?

--

System OK

Go to Step 5

12

Replace the solenoid.

Did you complete the replacement?

--

System OK

--