A/T - Erratic Operation

9216nissan03

Models (See below)

Section Automatic Transmission

Classification AT89-005

Bulletin No. TS89-051

Date April 13, 1989


ERRATIC AUTOMATIC TRANSMISSION OPERATION


APPLIED MODELS:
1984-1989 300ZX (Z31)
1987 Van (C22)
1986.5-1987 Truck (D21)
1987 Pathfinder (WD21)


SERVICE INFORMATION:

Some of the Applied Models equipped with automatic transmissions may exhibit intermittent and erratic shifting into and out of overdrive. Specific symptoms may include:

^ Random cycling in and out of overdrive.

^ The overdrive switch will not cancel overdrive.

^ The overdrive cancel light remains off with button in cancel position.

^ No upshift into overdrive.

^ The transmission downshifts into 3rd when letting up or off the accelerator above 45 mph.

^ The above symptoms may only occur with the engine fully warmed.

These symptoms may be caused by an erratic signal from the throttle sensor. The throttle sensor signal is used by the A/T control unit to control the overdrive shift pattern on these models.

SERVICE PROCEDURE

Perform the following procedure to determine if the throttle sensor is at fault:

1. Turn the ignition switch "ON".





2. Connect a voltmeter between terminal Nos. 4 and 5 of the A/T control unit (Figure 1).


3. Make sure the voltage changes smoothly as indicated below:


Model AT CLOSED THROTTLE AT FULL THROTTLE

^ 300ZX from 0.4 volts (apprx.) to 4.0 volts (apprx.)

^ Van, Truck, from 0.3 volts (apprx.) to 3.0 volts (apprx.) Pathfinder

4. If the voltage reading is O.K., monitor the voltage while driving with the symptoms present. If the voltage reading is still O.K., proceed to step No. 10.





5. If the voltage reading is erratic, verify the throttle sensor power source. Connect a voltmeter between terminal Nos. 3 and 5 of the A/T control unit (Figure 2).

6. Make sure the voltage remains at approximately 5 volts at all times. If O.K., proceed to Step 8.


7. If voltage reading is out of specification, check the 5 volt supply from the ECU and the wiring between the A/T control unit, throttle sensor and ECU. Repair as required and return to Step 1.





8. Disconnect the throttle sensor from the harness and check the resistance across terminals "e" and "f " of the throttle sensor connector (Figure 3).

NOTE: The resistance should increase smoothly from closed throttle to full throttle. If it doesn't, replace the throttle sensor and return to Step 1.


9. If the throttle sensor resistance is O.K., check the wiring between the throttle sensor and the A/T control unit. Repair as required and return to step No. 1.


10. If everything checks out O.K., but the symptoms still exist, refer to the appropriate service manual for further information.


PARTS INFORMATION:


MODEL DESCRIPTION PART NUMBER

300ZX Switch, throttle 22620-V7000


Van Switch, throttle 22620-41G01


Truck (Z24i) Switch, throttle 22620-41G01


Truck (VG30i) Switch, throttle 22620-12G01


Pathfinder (VG30i) Switch, throttle 22620-12G01