Diagnostics

Diagnosing an electronically controlled automatic transmission is simplified by using the following procedures. One of the most important things to remember is that there is a definite procedure to follow. DO NOT TAKE SHORT CUTS OR ASSUME THAT CRITICAL CHECKS OR ADJUSTMENTS HAVE ALREADY BEEN MADE. Follow the procedures as written to avoid missing critical components or steps. By following the diagnostic sequence, the service technician will be able to diagnose and repair the concern the first time.

On-Board Diagnostics with NGS

The Quick Tests are in the Powertrain Control/Emissions Diagnosis Manual (PC/ED). These tests can be used to diagnose thepowertrain control module (PCM) (12A650), sensors and actuators of the 4R70W transmission.

The following is a guide for using the On-Board Diagnostic (OBD) Quick Tests and the Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent, with some special considerations to remember.

NOTE: For detailed instructions and other diagnostic methods using the NGS, refer to the Powertrain Control/Emissions Diagnosis Manual OBDII or NGS instruction guide.

NOTE: If using a generic scan tool, refer to the Powertrain Control/Emissions Diagnosis Manual OBDII for instructions on performing OBDII procedures.

Quick Test 1.0 — Visual Inspection

Perform the Visual Check and Vehicle Preparation procedures as outlined in the Powertrain Control/Emissions Diagnosis Manual OBDII.

Inspect the following:

• Air cleaner and inlet ducting.
• All engine vacuum hoses for damage: leaks, cracks, blockage, proper routing, etc.
• PCM system wiring harnesses for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
• PCM, sensors and actuators for physical damage.
• Engine coolant for proper level.
• Transmission fluid for proper level and condition.
• Any non-factory installed items wired into the transmission or PCM harnesses.

NOTE: Perform all necessary service before continuing with Quick Tests.

Quick Test 2.0 — Setup

Connect Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent to data link connector (refer to vehicle owner manual for location).

The following are procedures to run OBDII procedures.

Vehicle and Tester Preparation

Prepare the vehicle as follows:

• Transmission range selector lever in PARK.
• Engine to operating temperature.
• Apply parking brake.
• Block wheels.
• Turn off all electrical loads including A/C and defroster. (If A/C is on, DTC P1460 will set.)

Prepare the NGS as follows:

• Key off.
• Verify that the proper PROGRAM card is inserted in the NGS.
• Connect J1962/16-way DCL cable adapter to the NGS.
• Connect NGS DCL cable adapter securely into the vehicle's data link connector.
• Connect the NGS power supply cable to the vehicle battery power supply through cigar lighter or at the battery with alligator clip adapter.
• Key on or start vehicle if necessary.
• The NGS is now ready to communicate with the PCM.

Quick Test 3.0 — Key On, Engine Off (KOEO)

 CAUTION: Do not replace parts based on a code, perform Pinpoint Tests first.

Some special considerations for Key On, Engine Off Quick Test include the following:

• The KOEO test provides hard Diagnostic Trouble Codes (DTCs) present at the time of testing.
• Always service the hard DTCs first.

Performing KOEO

• Perform visual inspection and vehicle preparation as required.
• Select "Vehicle and Engine Selection" menu.
• Select year, engine, model with the appropriate qualifier if needed, for example, transmission or 49 state/Cal.
• Select "Diagnostic Data Link" menu.
• Select "Diagnostic Test Mode" menu.
• Select "KOEO On-Demand Self Test."
• Follow operating instructions from the NGS menu screen.
• Record all DTCs displayed.
• Service non-transmission DTCs first as they can directly affect the operation of the transmission. Road test and repeat Quick Test to verify the service.

Quick Test 4.0 — Continuous Memory Codes

Continuous DTCs are concerns that were detected during normal vehicle operation. These codes are retained for 40 warm-up cycles.

Some special considerations for continuous testing include the following:

• The cause of some continuous DTCs may have been eliminated if KOEO and/or KOER DTCs were serviced. Always re-test and service any DTCs that still remain.
• If DTCs are present, refer to the Diagnostic Trouble Code Charts in the Diagnosis and Testing portion of this section for service information. Erase DTC, perform the Transmission Drive Cycle Test and repeat all Quick Test procedures after completing service on the DTCs.
• If the Continuous Test passes (P1111) and a concern is still present, refer to the Diagnosis by Symptom Index under Diagnosis by Symptom in the Diagnosis and Testing portion of this section. Also, refer to OASIS and TSBs for concern diagnosis.

Performing Continuous DTC Tests

• Select "Vehicle and Engine Selection" menu.
• Select year, engine, model with the appropriate qualifier if needed, for example, transmission or 49 state/Cal.
• Select "Diagnostic Data Link" menu.
• Select "Diagnostic Test Mode" menu.
• Select "Retrieve Continuous Codes."
• Follow operating instructions from the NGS menu screen.
• Record all DTCs displayed.
• Clear DTCs.
• Perform Transmission Drive Cycle Test.
• Rerun Continuous DTC Test, if DTCs have returned, and service as required. Road test and rerun all DTC test procedures.

Quick Test 5.0 — Key On, Engine Running (KOER)

The Engine Running Quick Test provides hard DTCs only.

Some special considerations for KOER Quick Test include the following:

• Follow the menu screen instructions as they appear.
• If a DTC appears after the KOER test, a malfunction is present. Refer to the Diagnostic Trouble Code Charts in the Diagnosis and Testing portion of this section for service information.

Performing KOER

• Perform visual inspection and vehicle preparation as required.
• Select "Vehicle and Engine Selection" menu.
• Select year, engine, model with the appropriate qualifier if needed, for example, transmission or 49 state/Cal.
• Select "Diagnostic Data Link" menu.
• Select "Diagnostic Test Mode" menu.
• Select "KOER On-Demand Self-Test."
• Follow operating instructions from the NGS menu screen (example: turn key on, etc.) and perform brake on/off (BOO) and cycle the transmission control switch (TCS) on and off, if equipped.
• Record all DTCs displayed.
• Service all non-transmission DTCs first as they can directly affect the operation of the transmission. Road test and repeat Quick Test to verify repair.

Special Test Modes

• Output Test Mode
• PCM Reset Mode (Clearing DTCs)

Output Test Mode

The Output Test Mode (OTM) aids in servicing output actuators associated with the OBDII system. It allows the technician to energize and de-energize most of the system output actuators on command.

Performing Output Test Mode (OTM)

NOTE: You must enter OTM with ignition key ON and the engine OFF.

• Perform visual inspection and vehicle preparation as required.
• Select "Vehicle and Engine Selection" menu.
• Select year, engine, model with the appropriate qualifier if needed, for example, transmission or 49 state/Cal.
• Select "Diagnostic Data Link" menu.
• Select "Diagnostic Test Mode" menu.
• Enter "Active Tests."
• Enter "Output Control."
• Follow operating instructions from the NGS menu screen.

PCM Reset Mode (Clearing DTCs)

The PCM Reset Mode provides a means for the NGS to command the PCM to clear all DTCs. When resetting the PCM, a DTC P1000 will be set in the PCM until all OBDII systems or components have been monitored during OBDII Drive Cycle. The following list is what happens when a PCM reset is performed.

• Clears the DTCs.
• Clears the freeze frame data.
• Clears the oxygen sensor test data.
• Resets the status of the OBDII system monitors.
• Sets the DTC No. P1000.

Performing PCM RESET:

• Perform visual inspection and vehicle preparation as required.
• Select "Vehicle and Engine Selection" menu.
• Select year, engine, model with the appropriate qualifier if needed, for example, transmission or 49 state/Cal.
• Select "Generic OBDII Functions" menu.
• Select "Clearing ALL Codes."
• Follow operating instructions from the NGS menu screen.
• Perform OBDII Drive Cycle — Clear No. P1000.

Clearing DTC No. P1000

Readiness for Inspection/Maintenance Testing

In some localities it may become a legal requirement to pass an inspection/maintenance (I/M) test of the OBDII system. If the vehicle powertrain system or the battery has just been serviced, the OBDII system is reset to a not ready for I/M testing condition. To prepare the vehicle for this test and to clear the DTC No. P1000 the OBDII Drive Cycle must be performed.

OBDII Drive Cycle

The following steps MUST BE RUN IN THE ORDER SHOWN. If steps 2, 3 or 4 are interrupted, repeat the step before proceeding. Any safe driving mode is acceptable between steps.

1. NOTE: Always drive vehicle in a safe manner according to traffic conditions and obey all traffic laws.

   Start engine and drive vehicle in typical city stop and go traffic for at least 10 minutes after if has reached normal operating temperature.

2. Idle vehicle for at least 45 seconds, then accelerate at part throttle to near 72 km/h (45 mph).

3. Then drive to accumulate at least 4 minutes in the range of 48 to 72 km/h (30 to 45 mph). If stop and go conditions occur, the designated accumulative time must be within the 32 to 72 km/h (20 to 45 mph) range. No wide-open throttle (WOT) conditions should be encountered.

4. Cruise and maintain a select speed in the range of 48 to 64 km/h (30 to 40 mph) on a level road with throttle held steady for at least one minute.

5. Decelerate and idle for at least one minute.

6. Accelerate to 89 km/h (55 mph) at 1/2 throttle (elapsed time is about 10 seconds).

7. Cruise and maintain a select speed in the range of 64 to 105 km/h (40 to 65 mph) on a level road with throttle held steady for at least one minute and 20 seconds.

8. Bring vehicle down to idle.

9. While the ignition key is on (vehicle at idle or engine off), check for continuous memory DTCs.

10. If system pass, OBDII Drive Cycle is complete. If DTC P1000 is received, check monitor completion status (On-Board Readiness Menu), and repeat the drive cycle.

Other NGS Features

For further information on other diagnostic testing features using the NGS or generic scan tool, refer to the Powertrain Control/Emissions Diagnosis Manual OBDII. Other diagnostic methods include the following:

• Parameter Identification (PID) Access Mode, used to monitor sensors and actuators.
• Freeze Frame Data Access Mode, used to view emission related data values from specific PIDs.
• Oxygen Sensor Monitor Mode, used to monitor the heated oxygen (HO2S) sensor.

Transmission Drive Cycle Test

After performing the Quick Test, use the following Transmission Drive Cycle Test for checking continuous codes.

1. NOTE: The Transmission Drive Cycle Test must be followed exactly. Malfunctions have to occur four times consecutively for codes P0781, P1731, P1732, P1733, P0782 and P0783 to be set, and five times consecutively for continuous code P0741.

   Record and then erase Quick Test DTCs.

2. Warm engine to normal operating temperature.

3. Make sure transmission fluid level is correct.

4. With transmission In OVERDRIVE, moderately accelerate from stop to 80 km/h (50 mph). This allows the transmission to shift into 4th gear. Hold speed and throttle open steady for a minimum of 15 seconds.

5. With transmission in OVERDRIVE, press transmission control switch (TCIL should illuminate) and moderately accelerate from stop to 64 km/h (40 mph). This allows transmission to shift into third gear. Hold speed and throttle open steady for a minimum of 15 seconds (30 seconds above 4,000 feet).

6. Press TCS (TCIL should turn off) and accelerate from 64 km/h (40 mph) to 80 km/h (50 mph). This allows transmission to shift into 4th gear. Hold speed and throttle position steady for a minimum of 15 seconds.

7. With transmission in 4th gear and maintaining steady speed and throttle opening, lightly apply and release brake pedal (to operate stoplamps). Then hold speed and throttle steady for an additional 5 seconds (minimum).

8. Brake to a stop and remain stopped for a minimum of 20 seconds.

9. Repeat Steps 4 through 8 at least five times.

10. Perform Quick Test and record continuous codes.