GM Service Manual Online
For 1990-2009 cars only

Object Number: 174754  Size: SF
ABS Components
Antilock Brake System Schematics

Circuit Description

The traction control system primarily uses the ECM fuel and the ignition controls to limit drive wheel slippage during acceleration. In addition to engine torque reduction, the TCM monitors the requested engine torque circuit from the EBTCM. When the EBTCM sends a torque request to the ECM and the TCM via a Pulse Width Modulated (PWM) signal, this commands the TCM to prevent transmission down shift thus limiting drive wheel slippage during acceleration. The TCM then provides a delivered torque PWM signal informing the EBTCM how much actual torque is produced by the transmission.

Conditions for Setting the DTC

    • The EBTCM does not receive 2 delivered transmission torque signals within 250 milliseconds of each other, 2 seconds after initialization.
    • There is an open in the circuit.
    • There is a short to ground in the circuit.
    • There is a short to voltage in the circuit.
    • The EBTCM must detect an engine RPM greater than 480 RPM to set the DTC.

Action Taken When the DTC Sets

    • A malfunction DTC is stored.
    • The TC indicator lamp is turned on.
    • The TCS is disabled.
    • The ABS remains functional.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The scan tool Clear DTCs function is used.
    • 100 drive cycles have passed with no DTCs detected.

Diagnostic Aids

The following can cause an intermittent malfunction:

    • A poor connection can cause an intermittent malfunction.
    • Rubbed through wire insulation can cause an intermittent malfunction.
    • A wire that is broken inside the insulation can cause an intermittent malfunction.

Check for the following in any circuit suspected of causing an intermittent malfunction:

    • Check for backed out terminals.
    • Check for improper mating.
    • Check for broken locks.
    • Check for improperly formed terminals.
    • Check for damaged terminals.
    • Check for poor terminal to wiring connections.
    • Check for physical damage to the wiring harness.

Perform a thorough inspection of the wiring. Perform a thorough inspection of the connectors. Failure to carefully and fully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis causes part replacement with reappearance of the malfunction.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. It is very important to check ground G103. Corrosion or a loose connection at this point may cause a malfunction in the PWM signal.

  2. The scan tool can be used to check the delivered transmission torque signal from the Transmission Control Module. It should remain generally steady with the gear selector in drive.

  3. This test checks the presents of a pull-up voltage from the EBTCM.

DTC 71 - Delivered Transmission Torque Circuit Malfunction

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to A Diagnostic System Check

2

Check that ground G103 is clean and check that ground G103 is torqued to the proper specifications. Refer to Ground Distribution Schematics in Wiring Systems for ground specifications and ground locations.

Are the following signs evident:

    • Is the ground loose?
    • Is the ground damaged?
    • Is the ground corroded?

--

Go to Step 18

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Install a scan tool.
  3. Start the engine.
  4. Use the scan tool to select Data Display.
  5. Move the gear selector to drive (while foot is on the brake) with the engine running.
  6. Observe the Delivered Transmission Torque.

Is the percent of delivered torque within the specified range?

20-30%

Go to Step 6

Go to Step 4

4

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the TCM connector.
  3. Turn the ignition switch to the RUN position with the engine off.
  4. Use a J 39200 DMM to measure the voltage between the TCM harness connector terminal 10 and ground.

Is the voltage measured equal to or greater than the specified voltage?

10 V

Go to Step 5

Go to Step 7

5

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the 25-way EBTCM connector C1.
  3. Install a J 39700 Universal Breakout Box with a J 39700-250 Cable Adapter to the EBTCM harness connector only.
  4. Turn the ignition switch to the RUN position with the engine off.
  5. Use a J 39200 DMM to measure the voltage between the J 39700 terminal 17 and ground.

Is the voltage measured within the specified range?

0-2 V

Go to Step 9

Go to Step 12

6

  1. Turn the ignition switch to the OFF position.
  2. Inspect the following:
  3. • Inspect the delivered transmission torque circuit for signs of damage which may result in the following:
       - Inspect for an intermittent open.
       - Inspect for an intermittent short to ground.
       - Inspect for an intermittent short to voltage.
    • Inspect the 25-way EBTCM harness connector C1, terminal 17 for signs of damage which may result in the following:
       - Inspect for an intermittent open.
       - Inspect for an intermittent short to ground.
       - Inspect for an intermittent short to voltage.
    • Inspect the TCM harness connector terminal 10 for signs of damage which may result in the following:
       - Inspect for an intermittent open.
       - Inspect for an intermittent short to ground.
       - Inspect for an intermittent short to voltage.
  4. Inspect the remaining terminals of the 25-way EBTCM harness connector C1 for the following signs:
  5. • Inspect for signs of damage.
    • Inspect for signs of poor terminal contact.
    • Inspect for signs of terminal corrosion.

Are the following signs evident:

    • Is poor terminal contact evident?
    • Is corrosion evident?
    • Is damage evident?

--

Go to Step 15

Go to Step 11

7

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the 25-way EBTCM connector C1.
  3. Install a J 39700 Universal Breakout Box with a J 39700-250 Cable Adapter to the EBTCM harness connector only.
  4. Use a J 39200 DMM to measure the resistance between the J 39700 terminal 17 and the TCM harness connector terminal 10.

Is the resistance within the specified range?

0-2 ohms

Go to Step 8

Go to Step 13

8

Use a J 39200 DMM to measure the resistance between the J 39700 terminal 17 and ground.

Is the resistance within the specified range?

OL (Infinite)

Go to Step 19

Go to Step 14

9

  1. Turn the ignition switch to the OFF position.
  2. Inspect the 25-way EBTCM harness connector C1, terminal 17 and inspect the TCM harness connector terminal 10 for the following signs of damage:
  3. • Inspect for poor terminal contact.
    • Inspect for terminal corrosion.
  4. Inspect the remaining terminals of the 25-way EBTCM harness connector C1 for the following signs of damage:
  5. • Inspect for poor terminal contact.
    • Inspect for terminal corrosion.

Are the following signs evident:

    • Is poor terminal contact evident?
    • Is corrosion evident.
    • Is damage evident?

--

Go to Step 15

Go to Step 10

10

  1. Reconnect the TCM connector.
  2. Reconnect the 25-way EBTCM connector C1.
  3. Test drive the vehicle over 6 km/h (4 mph) for 30 seconds.
  4. Use the scan tool to read the DTCs.

Did DTC 71 reset?

--

Go to Step 16

Go to Step 17

11

  1. Reconnect the TCM connector.
  2. Reconnect the 25-way EBTCM connector C1.
  3. Test drive the vehicle over 6 km/h (4 mph) for 30 seconds.
  4. Use the scan tool to read the DTCs.

Did DTC 71 reset?

--

Go to Step 19

Go to Step 17

12

Repair the short to voltage in the delivered transmission torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to A Diagnostic System Check

--

13

Repair an open or repair a high resistance in the delivered transmission torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to A Diagnostic System Check

--

14

Repair a short to ground in the delivered transmission torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to A Diagnostic System Check

--

15

Replace all the terminals or replace the connectors that exhibit signs of the following:

    • Replace the connectors that exhibit poor terminals.
    • Replace the connectors that exhibit terminal corrosion.
    • Replace the connectors that exhibit damage.

Refer to Connector Repairs or Repairing Connector Terminals in Wiring Systems.

Is the repair complete?

--

Go to A Diagnostic System Check

--

16

Suspect TCM. Refer to On-Board Diagnostic System Check in Automatic Transaxle - 4L30-E.

Is the diagnosis complete?

--

Go to A Diagnostic System Check

--

17

The malfunction is intermittent or the malfunction is not present at this time. Refer to Diagnostic Aids for more information.

Is the diagnosis complete?

--

Go to A Diagnostic System Check

--

18

Repair the ground as necessary. Refer to Wiring Repairs in Wiring Systems if the ground terminal requires replacement.

Is the repair complete?

--

Go to A Diagnostic System Check

--

19

Replace the EBTCM. Refer to EBTCM Replacement .

Is the repair complete?

--

Go to A Diagnostic System Check

--