Description
Important: Do not perform this diagnostic if no driveability concern exists. A driveability condition includes all PCM controlled systems and components.
The Powertrain OBD System Check is an organized approach to identifying a concern created by an electronic engine control system malfunction. The Powertrain OBD System Check is the starting point for any driveability concern diagnosis. The Powertrain OBD System Check directs the service technician to the next logical step in diagnosing a concern. Understanding and using the table correctly will reduce the diagnostic time and prevent the replacement of good parts.
Important: For automatic transmission DTCs, refer to
Diagnostic Trouble Code Identification
in Automatic Transmission-4L60E
for diagnosis procedures. The DTCs associated with the automatic transmission
are:
• DTCs P0502 and P0503. • Any 700 (except P0704, P0705 and P0706) and 1800 series DTCs (i.e.
DTC P07XX and P18XX).
Important: For Domestic and Export DTC Types, refer to Diagnostic Trouble Code (DTC) List .
Important:
• When the Body Control Module (BCM) is replaced, the PCM password
Learn procedure must be performed. Refer to
DTC P1631 Theft Deterrent Start Enable Signal Not Correct
for the learn procedure. • This vehicle is equipped with a Powertrain Control Module (PCM)
utilizing an Electrically Erasable Programmable Read Only Memory (EEPROM).
Program the new PCM when diagnostics call for replacement of the PCM.
When the PCM is replaced the following must be performed: - The PCM must be programmed. Refer to
Powertrain Control Module/Throttle Actuator Control Module Replacement
. - The PCM Password learn procedure must be performed. Refer to
DTC P1631 Theft Deterrent Start Enable Signal Not Correct
for procedure. - The Idle Learn Procedure. Refer to PCM Idle Learn Procedure
.
Diagnostic Aids
This vehicle has a column lock system. This system is necessary because of the location of the ignition lock cylinder. The BCM controls a motor mounted on the steering column. The purpose of the motor is to unlock the steering wheel. The PCM will disable the fuel if the BCM is unable to determine if either the column is unlocked or vehicle speed is present. Refer to Diagnostic System Check - Body Control System in Body Control Systems for more information on the column lock system.
Important: If an intermittent condition exists, inspect the PCM wiring harnesses for improper installation of electrical components. Inspect for aftermarket theft deterrent devices, lights, and cellular phones. Ensure that no aftermarket equipment is connected to the Class 2 circuit. A cellular phone signal communication may cause an intermittent condition.
If multiple DTCs are set, inspect the IGN relay for proper operation. Refer to Ignition Relay Diagnosis .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Use a properly functioning scan tool with the diagnostic tables in this section. DO NOT use the Clear Info function unless instructed by a diagnostic procedure.
-
This step determines if any other modules on the Class 2 circuit can communicate. If the scan tool displays Waiting for Data, the class 2 circuit is shorted to ground.
-
An ignition 1 voltage that is low may cause the following conditions:
-
This step tests for DTCs associated with the Vehicle Theft Deterrent system which prevents the engine from starting.
-
This condition may indicate a concern with the Column Lock system.
-
If multiple DTCs are stored, diagnose in the following order of priority:
| • | A no start |
| • | Stalling |
| • | High engine idle |
| • | No scan tool communications |
| 1. | PCM/TAC failure DTCs (P0601, P0602, P0604, P0606, P1517, P1518) |
| 2. | System Voltage DTCs |
| 3. | Component level DTCs (Sensors, Solenoids, Relays etc.). Multiple DTCs within this category should be diagnosed in numerical order starting with the lowest numbered DTC. |
| 4. | System level DTCs (Misfire, Fuel Trim, etc.) |
It is beneficial to review the Freeze Frame Data and/or Fail Records. Use the odometer information and the fail counter in order to determine how frequently and how recently the DTC set. This information and the other operating conditions when the DTC set may help diagnose an intermittent condition. Capturing the stored info preserves data that the PCM will lose when instructed to Clear Info at the end of a diagnostic table, or if you disconnect the PCM or replace the PCM during a diagnostic procedure. The scan tool stores the data in the scan tool's memory. Review the captured info at the end of the diagnostic procedure in order to catch the next DTC in the event there are multiple DTCs stored. Follow the order of priority as listed above.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
Important:
Does the scan tool power-up? | -- | |||||||||
2 |
Important: If the scan tool communicates with the PCM, Save or Capture (Store Information) the DTC Information and the Freeze Frame and/or Failure Records information. Does the scan tool display PCM data? | -- | ||||||||
Use a scan tool in order to select the Diagnostic Circuit Check and the Class 2 Message Monitor. Does the scan tool display any other modules as active? | -- | Go to Diagnostic System Check - Data Link Communications in Data Link Communications | ||||||||
|
Important: If the starter does not engage, refer to Starter Solenoid Does Not Click in Engine Electrical. Monitor the Ignition 1 voltage using a scan tool while cranking the engine or while the engine is operating. Is the Ignition 1 voltage near the specified value? | B+ | |||||||||
5 | Does the engine start and continue to operate? | -- | ||||||||
Are there any PCM/BCM DTCs set for the Vehicle Theft Deterrent System? | -- | Go to applicable DTC | ||||||||
Monitor the following Column Lock parameters on the scan tool.
Does any of the Column Lock parameters indicate a malfunction with the column lock system? | -- | Go to Diagnostic System Check - Body Control System in Body Control System or Diagnostic System Check - Data Link Communications in Data Link Communications or Diagnostic System Check - ABS in Antilock Brake System | ||||||||
|
Important: Save or capture (Store Information) the DTC Information and the Freeze Frame and/or Failure Records information. Monitor the DTC Information using a scan tool. Are any DTCs displayed? | -- | Go to the applicable DTC table | ||||||||
Compare the scan tool data with the values shown in the Engine Scan Tool Data List . Are the values normal or within typical ranges? | -- | Go to Symptoms | Go to Diagnostic Aids and Test Descriptions |
