A/T - RE4F02A Soft Shift or Slip

TECHNICAL BULLETIN # 161

TRANSMISSION: RE4F02A

SUBJECT: SOFT SHIFTS/SLIPS

APPLICATION: NISSAN MAXIMA/STANZA

DATE: April 93

NISSAN MAXIMA/STANZA

RE4F02A SOFT SHIFTS/SLIPS

A soft shift or slip complaint on an RE4F02A is usually caused by a worn out pressure control solenoid. Use the following steps to isolate the problem.





[STEP 1.]
Check mainline pressure in drive, (see Figure 1).
It should be 55-66 PSI at an idle, 186-198 PSI at a stall.

If line doesn't rise (or rises very little) try the stall test again with the solenoid wires disconnected.

If the pressure rises to maximum, go to STEP 2.

If line pressure is still low you may have a stuck slide, valve body problem, a leaking pressure control solenoid or "O" ring, control cylinder, etc.





To check for a stuck slide, remove the control cylinder and stick a long screwdriver down the control cylinder rod hole, (see Figure 2).

When you push on the screwdriver you should feel the slide move and the spring compress.

To check the solenoid, pour solvent down the neck.
It shouldn't leak, if it does, replace it.





While you have the solenoid off, blow air into the valve body where the solenoid fits, (see Figure 3).
You should be able to hear the Pressure Regulator boost valve stroke.

[STEP 2.] Check the voltage to the pressure control solenoid, (with the solenoid CONNECTED).

This can be done at the transmission harness
(it's the wire with 2.5-5 Ohms resistance)
or at the computer (see ATRA Bulletin # 149).

The voltage should be 1.5-2.5V at closed throttle and drop to .5V at WOT.
If it does, replace the solenoid pack. The part number is 31940-27X66.

If the voltage does not drop, the problem is computer related (TPS, bad ground, etc.).
To check the computer, refer to the pinpoint test shown in ATRA Bulletin # 149.

Note
Most line rise problems are solenoid related. If the unit has more than 50.000 miles, the solenoids should be replaced during rebuild.