Diagnostic System Check - Automatic Transmission. Cadillac CTS 2004

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 5L40-E 🢒 Diagnostic System Check - Automatic Transmission

Description

Important: Do not perform the Diagnostic System Check-Automatic Transmission unless one of the concerns noted is present. Failure to follow this procedure could lead to misdiagnosis of the system.

The Diagnostic System Check-Automatic Transmission is an organized approach to identifying a condition created by an electronic transmission control system. The Diagnostic System Check-Automatic Transmission is intended for use in diagnosing a concern in a vehicle with separate engine and transmission control modules, ECM and TCM.

When an emission related diagnostic trouble code (DTC) sets as a result of a transmission fault, the TCM requests the ECM to illuminate the malfunction indicator lamp (MIL). This request will be identified by the ECM as DTC P0700. The ECM may also independently illuminate the MIL. Although either module may cause the MIL to illuminate, the scan tool can display DTCs from only one module at a time. In addition, the Clear DTC Info command clears DTC data from both modules. If the DTC failure records are not recorded from both modules before the DTC data is cleared, important diagnostic information will be erased.

Your training and experience as a technician may cause you to focus on either the TCM or the ECM, instead of both modules at the same time. To ensure that both modules are properly diagnosed, separate system checks are included. The Diagnostic System Check - Engine Controls in Engine Controls - 2.6L and 3.2L or Diagnostic System Check - Engine Controls in Engine Controls - 3.6L identifies DTC status and communication function for the ECM. If no ECM DTCs are present, the Diagnostic System Check - Engine Controls in Engine Controls - 2.6L and 3.2L or Diagnostic System Check - Engine Controls in Engine Controls - 3.6L will direct you to the Diagnostic System Check-Automatic Transmission.

The ECM diagnostics do not require transmission data in order to run. Correct use of the tables will reduce diagnostic time and prevent the replacement of good parts.

Diagnostic Aids

Inspect all of the related wiring and connections including the connections at the TCM, as these may cause an intermittent concern. Inspect the terminals for any damage or any corrosion. Inspect the connector for any pushed-out terminals.

Step

Action

Yes

Perform the following preliminary inspections:

•	Ensure that the battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.

•	Ensure that the battery cables are clean and tight.

•	Inspect the easily accessible systems of the visible system components for obvious damage or conditions that could cause the symptom. Refer to Strategy Based Diagnosis in General Information.

•	Ensure that the engine and control module grounds are clean, tight, and in the correct location.

•	Inspect for aftermarket devices that could affect the operation of the system. Refer to Checking Aftermarket Accessories in Wiring Systems.

•	Ensure the resistance between the TCM housing and the battery negative cable is less than 0.5 ohms.

Did you find and correct the condition?

System OK

Go to Step 2

Turn ON the ignition, with the engine OFF.
Attempt to establish communication with the listed control modules:

•	Transmission control module (TCM)

•	Engine control module (ECM)

•	Electronic brake control module (EBCM)

•	Instrument panel cluster (IPC)

•	HVAC control module

•	Theft deterrent control module

Does the scan tool communicate with all the listed control modules?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Important: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.

Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool.
Rotate the ignition switch through all positions while observing the ignition switch power mode parameter. Refer to Body Control System Description and Operation in Body Control Systems for a list of the power mode states that correspond to each ignition switch position.

Does the ignition switch parameter reading match the ignition switch position for all switch positions?

Go to Step 4

Go to Power Mode Mismatch in Body Control System

Attempt to start the engine.

Does the engine crank?

Go to Step 5

Go to Symptoms - Engine Electrical in Engine Electrical

Did the engine start and idle?

Go to Step 6

Go to Engine Cranks but Does Not Run in Engine Controls - 2.6 and 3.2L or Engine Cranks but Does Not Run in Engine Controls - 3.6L

Important: Do NOT clear the DTCs unless instructed by a diagnostic procedure.

Select the DTC display function for the following control modules and record the DTCs:

•	Transmission control module (TCM)

•	Engine control module (ECM)

•	Electronic brake control module (EBCM)

•	Instrument panel cluster (IPC)

•	HVAC control module

•	Theft deterrent control module

IF multiple powertrain DTCs are stored, diagnose the DTCs in the following order:

Test for component lever DTCs. For example, sensor DTCs, then solenoid DTCs. Begin with the lowest number DTC unless the diagnostic table directs you otherwise.