GM Service Manual Online
For 1990-2009 cars only

Object Number: 1570394  Size: SF
Automatic Transmission Controls Schematics

Circuit Description

The transmission control module (TCM) receives an engine coolant temperature signal from the engine control module (ECM). The TCM uses this information to delay torque converter clutch operation until the vehicle has reached an operating temperature of 30°C (86°F).

DTC Detecting Condition

The following engine coolant temperature signals are detected by the TCM while the engine running:

    • 10 Hz (100 ms/cycle) signal being 0% ON (10-14 V) for 2.5 seconds
    • 10 Hz (100 ms/cycle) signal being 100% ON (about 0 V) after 15 minutes from engine start

Action Taken When the DTC Sets

    • DTC P1705 is stored.
    • The OD/OFF indicator turns ON.
    • The malfunction indicator lamp (MIL) turns ON.

Diagnostic Aids

An intermittent condition may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Inspect the TCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and for poor terminal-to-wire connections.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step checks for DTC P0117 or DTC P0118 stored in the ECM and to proceed to their respective diagnostic charts first.

  2. This step checks for proper voltage values.

  3. This step checks for poor ECM connector terminal contact.

  4. This step determines whether the condition is intermittent and not caused by a defective ECM.

  5. This step checks for a short to ground in PNK/BLU wire.

  6. This step checks for an open in the PNK/BLU wire.

  7. This step determines whether the condition is intermittent and not caused by a defective TCM.

Step

Action

Value(s)

Yes

No

1

Was the On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to On-Board Diagnostic System Check

2

  1. Turn the ignition switch to ON.
  2. Using a scan tool, read the DTCs.

Is DTC P0117 or DTC P0118 currently set in the ECM?

--

Go to the applicable DTC table in Engine Controls.

Go to Step 3

3

  1. Turn the ignition switch to LOCK.
  2. Disconnect the ECM electrical connector C2.
  3. Disconnect the main relay. Refer to Main Relay Replacement in Engine Electrical.
  4. Using a J 36169-A Fused Jumper with a 15A fuse, connect terminals 1 (BLK/WHT) and 4 (BLU/BLK) of the main relay harness connector.
  5. Turn the ignition switch to ON.
  6. Using a DVM, measure the voltage between ground and ECM harness connector C2 terminal 16.

Is the voltage within the specified range?

10-14 V

Go to Step 4

Go to Step 6

4

Inspect the ECM connector C2 terminal 16 for poor contact.

Is poor terminal contact or a poor connection evident?

--

Go to Step 8

Go to Step 5

5

  1. Turn the ignition key to LOCK.
  2. Reconnect the ECM connector.
  3. Reconnect the main relay.
  4. Clear the DTCs.
  5. Start the engine and run for 15 minutes.

Does the DTC reset?

--

Go to Step 10

Go to Step 11

6

  1. Turn the ignition key to LOCK.
  2. Disconnect the TCM.
  3. Using a DVM, measure the resistance between ground ECM harness connector C2 terminal 16.

Is the resistance less than the specified value?

2 ohms

Go to Step 9

Go to Step 7

7

Using the DVM, measure the resistance between the ECM C2 terminal 16 and TCM harness connector terminal 1.

Is the resistance less than the specified value?

2 ohms

Go to Step 13

Go to Step 12

8

Repair terminals or connection integrity that exhibits poor contact and recheck.

Is the action complete?

--

Go to Step 15

--

9

Repair the short to ground in the PNK/GRN wire between the ECM and TCM.

Is the action complete?

--

Go to Step 15

--

10

Replace the ECM.

Is the action complete?

--

Go to Step 15

--

11

Refer to Diagnostic Aids in order to correct a possible intermittent malfunction.

Is the procedure complete?

--

Go to Step 15

--

12

Repair open or high resistance in PNK/GRN wire between the ECM and TCM.

Is the action complete?

--

Go to Step 15

--

13

  1. Reconnect the TCM and ECM.
  2. Reconnect the main relay.
  3. Clear the DTCs.
  4. Start the engine and run for 15 minutes.

Does the DTC reset?

--

Go to Step 14

Go to Step 11

14

Replace the TCM.

Is the action complete?

--

Go to Step 15

--

15

  1. Reconnect the connectors.
  2. Perform the DTC Confirmation Procedure.

Does the scan tool display any DTCs?

--

Go to the applicable DTC table

--