SMU - Revised ABS/TC Diagnostic Table for DTC 67 Requested Engine Torque Circuit Malfunction. Cadillac Catera 1997

Subject:

Revised ABS/TC Diagnostic Table for DTC 67 Requested Engine Torque Circuit Malfunction

Models:

1997 Cadillac Catera

This bulletin is being issued to revise the Diagnostic Routines for DTC 67. This additional information is being added to conditions for setting the DTC and in the Diagnostic Table Step 2. The technician is directed to check for DTCs stored in the ECM. The knock sensor DTCs P0325 and P0330 will set in the ECM and cause DTC 67 to set in the EBTCM if a torque reduction is requested. This condition will not turn on the Service Engine Soon (SES) indicator until a second knock sensor failure. Therefore, the technician will not realize to check the ECM for DTCs when diagnosing the EBTCM DTC 67. Please use the following to replace the existing information in the ABS/Traction Control sub-section of the Service Manual.

This information has been updated within SI 2000. If you are using a paper version of this Service Manual, please mark a reference to this bulletin on the affected page in the ABS/Traction Control sub-section of the Service Manual.

Circuit Description

The traction control system uses the ECM fuel and the ignition controls to limit the drive wheel slippage during acceleration. The ECM reduces engine torque by retarding spark timing, and/or shutting off up to three injectors. The EBTCM sends a torque request to the ECM via a Pulse Width Modulated (PWM) signal requesting the desired torque level for proper traction control system operation. The ECM then provides a delivered torque PWM signal informing the EBTCM how much actual torque is produced by the engine.

Conditions for Setting the DTC

•	If a defective requested torque signal is detected by the ECM, a PWM signal outside the normal range is sent to the EBTCM via the delivered torque circuit. The DTC will set if the EBTCM receives the out of range signal 3 consecutive times.

•	The ECM can not carry out a requested torque reduction when a knock sensor DTC is set. When the knock sensor DTC is set, the ECM sends the EBTCM an invalid PWM signal which will set an ECM and EBTCM DTC and disable the TCS.

•	There is an open in the circuit.

•	There is a short to ground.

•	There is a short to voltage.

•	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 SES indicator lamp is turned on when the knock sensor fails a second consecutive drive trip that the diagnostic runs and fails.

•	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.

This verifies that a knock sensor DTC is present.

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

The scan tool can be used to check the requested engine torque signal from the EBTCM. The reading should remain steady when TCS is inactive. The reading will fluctuate between 2% and 10% if observed when TCS is active.

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

DTC 67 - Requested Engine Torque Circuit Malfunction

Step

Action

Value(s)

Yes

Was the Diagnostic System Check performed?

Go to Step 2

Go to A Diagnostic System Check

Turn the ignition switch to the OFF position.
Install a scan tool.
Turn the ignition switch to the RUN position.
Use the scan tool to select Freeze Frame/Failure Records, Last Test Fail in Powertrain.
Observe the DTCs that have failed the last test.

Did the DTC P0325 or P0330 fail the last test?

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls.

Go to Step 3

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 19

Go to Step 4

Turn the ignition switch to the RUN position.
Use the scan tool to select Engine Data Display in Powertrain.
Observe the TC Torque Request.

Is the percent of TC Torque Request within the specified range?

6-10%

Go to Step 7

Go to Step 5

Turn the ignition switch to the OFF position.
Disconnect the ECM connector.
Disconnect the TCM connector.
Turn the ignition switch to the RUN position with the engine off.
Use a J 39200 DMM to measure the voltage between the ECM harness connector terminal 48 and ground.

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

8 V

Go to Step 6

Go to Step 8

Turn the ignition switch to the OFF position.
Disconnect the 25-way EBTCM connector C1.
Install a J 39700 Universal Breakout Box with a J 39700-250 Cable Adapter to the EBTCM harness connector only.
Turn the ignition switch to the RUN position with the engine off.
Use a J 39200 DMM to measure the voltage between the J 39700 terminal 14 and ground.

Is the voltage measured within the specified range?

0-2 V

Go to Step 10

Go to Step 13

Turn the ignition switch to the OFF position.
Inspect the following:

•	Inspect the delivered engine 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 14 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 ECM harness connector terminal 48 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 9 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 remaining terminals of the 25-way EBTCM harness connector C1 for the following signs:

•	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 16

Go to Step 12

Turn the ignition switch to the OFF position.
Disconnect the 25-way EBTCM connector C1.
Install a J 39700 Universal Breakout Box with a J 39700-250 Cable Adapter to the EBTCM harness connector only.
Use a J 39200 DMM to measure the resistance between the J 39700 terminal 14 and the ECM harness connector terminal 48.

Is the resistance within the specified range?

0-2 ohms

Go to Step 9

Go to Step 14

Use a J 39200 DMM to measure the resistance between the J 39700 Universal Breakout Box terminal 14 and ground.

Is the resistance within the specified range?

OL (Infinite)

Go to Step 20

Go to Step 15

Turn the ignition switch to the OFF position.
Inspect the 25-way EBTCM harness connector C1, terminal 14 and inspect the ECM harness connector terminal 48 for the following signs of damage:

•	Inspect for poor terminal contact.

•	Inspect for terminal corrosion.

Inspect the remaining terminals of the 25-way EBTCM harness connector C1 for the following signs of damage:

•	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 16

Go to Step 11

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

Did DTC 67 reset?

Go to Step 17

Go to Step 18

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

Did DTC 67 reset?

Go to Step 20

Go to Step 18

Repair the short to voltage in the requested engine torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to A Diagnostic System Check

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

Is the repair complete?

Go to A Diagnostic System Check

Repair a short to ground in the requested engine torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to A Diagnostic System Check

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

Suspect ECM. Refer to Powertrain On Board Diagnostic (OBD) System in Engine Control.

Is the diagnosis complete?

Go to A Diagnostic System Check

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

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

Replace the EBTCM. Refer to EBTCM Replacement .

Is the repair complete?

Go to A Diagnostic System Check