MIL ON - DTC P0731,P0732,P0733 (A/T Signals) No Symptoms

Classification:
AT97-001

Reference:
NTB97-028

Date:
April 16, 1997

DIAGNOSTIC PROCEDURE FOR P0731, P0732 & P0733 (A/T
SIGNALS) WITH NO DRIVEABILITY INCIDENTS

APPLIED VEHICLE(S):
1995 & later Maxima (A32)
1995 & later Sentra/200SX (B14); SR20 engine only
1997 & later Truck (D21)
1996 & later Pathfinder (R50)
1996 & later 240SX (S14)
1996 & later Altima (U13)
1996 & later Quest (V40)
1996 300ZX (Z32)

APPLIED TRANSMISSION # (S):

Automatic transmission with OBD-II only

SERVICE INFORMATION

If an applied vehicle has a MIL "on" condition with P0731, P0732 or P0733 stored with no driveability (shift shock, slipping, etc.) incidents, use the procedure in this bulletin to diagnose and repair the incident.

These codes can be retrieved only in the ENGINE SYST section of CONSULT. These codes will not be recorded in the A/T SYST section of CONSULT

SERVICE PROCEDURE

Confirmation

1. Connect CONSULT. Confirm the throttle position sensor (TPS) setting is correct as follows:

2. Bring the engine to normal operating temperature.





3. Select A/T, then DATA MONITOR then SELECTION FROM MENU (see Figure 1).

4. Select VHCL/S SE A/T, THRTL POS SEN and ENGINE SPEED.

5. Then select CLOSED THL/SW, GEAR, THROTTLE POSI and VEHICLE SPEED. PRESS ENTER TO SAVE THESE SELECTIONS.

6. Press Settings and select HI SPEED/MANU TRIG. Press START and watch the data.

7. Road test the vehicle. Accelerate to approximately 40 mph. Release the throttle until the CONSULT shows the CLOSED THL/SW is in the "ON" position.

8. Let the vehicle coast and push RECORD on CONSULT (data). When the recording is completed, display the record on CONSULT and look for a voltage increase at the TPS output.

- The TPS voltage with close throttle switch "ON" should be within the service manual specifications (refer to the AT section of the appropriate service manual).

- The TPS voltage should never go above the service manual idle specification when the close throttle switch is "ON".

Root Cause (example - main concern is the TPS voltage)





The automatic transmission control unit (ATCU) uses the TPS voltage to monitor driving conditions (acceleration or deceleration). When the TPS voltage increases above 1.0 volts (with close throttle switch "ON" & vehicle in deceleration) the ATCU goes into diagnostic for A/T signals. If the ATCU does not see an increase in vehicle speed within 3 seconds, an A/T signal DTC will be tripped (see Figure 2, engine speed and throttle position are not shown).

NOTE:
Close throttle switch is "ON" the entire time.

NOTES:

1. Throttle is "OFF" (close throttle switch is "ON").

2. TPS voltage is increasing (ATCU thinks the vehicle is accelerating); but the vehicle speed is actually decreasing.

Repair

1. If you can duplicate the MIL "on" incident with the Confirmation procedure, replace the TPS to resolve the incident.

2. You must adjust the TPS after installation. Refer to the EC section under Basic Inspection in the appropriate service manual.

3. After the TPS adjustment, you must re-set the idle position memory. Refer to the EC section under Basic Inspection, RESET IDLE POSITION MEMORY in the appropriate service manual.

4. After resetting the idle position, verify the engine RPM at idle.

5. After step 4, you must check the TPS output voltage at idle. Make sure there is no duplication of the same incident.

6. Perform the Confirmation procedure again.





PARTS INFORMATION

CLAIMS INFORMATION

When applicable, normal claims coding applies.