A/T - RL4R01A Soft Shifts, Slips Under Heavy Throttle
TECHNICAL BULLETIN # 258ATRANSMISSION: RE4R01A
SUBJECT:
Soft shifts, slips at heavy throttle, no/low line rise
APPLICATION: Nissan, Mazda
DATE: 1994
RE4R01A, RE4R03A, R4A-EL
Soft Shifts, Slips At Heavy Throttle, No/Low Line Rise
All of these problems can and usually are caused by a worn (leaking) line pressure solenoid.
Use the following procedure to check the mechanical operation of the solenoid.
[Step 1] Check Line Rise.
Line pressure will vary from model to model, however, there should be approximately 57-74 psi at an idle and 148-186 psi at a stall. If line rise is normal, the shift concern is not line pressure solenoid related. Check for internal leaks (e.g. lip seals, accumulator seats, etc.). If line pressure does not rise or rises very little, go to step two.
[Step 2] Disconnect The Solenoid Harness Connector
Line pressure should rise to maximum when the solenoid harness is disconnected. If line pressure rises, go to step three. If line pressure does not rise, check the following:
1. Check for a stuck pump slide (see bulletin # 144).
2. Check the pilot valve and the pressure modifier valve, they may be stuck (figure one).
The original bulletin had errors in the transmission identification. Remove # 258 from your files and replace with this bulletin # 258A.
[Step 3] Check The Voltage To The Line Pressure Solenoid.
There are several configurations of harness connectors. The easiest way to find the line pressure solenoid wire is to check its resistance. The line pressure solenoid resistance is 2.5-5 ohms.
The other solenoids have significantly higher resistance. Reconnect the solenoid harness. Check the voltage to the line pressure solenoid (piercing wiring insulation is necessary).
The voltage to the line pressure solenoid should be 1.5-2.5 volts in drive at an idle. The voltage should drop to approximately .5 volts at a stall. If the voltage does not change, the problem is computer related (e.g. throttle position sensor, controller, etc.). If the voltage varies, relace the line pressure solenoid. When working on a Nissan, it is best to replace the entire solenoid pack. The solenoid pack consists of all four solenoids. (figure two).
The cost of the solenoid pack is not much greater than the line pressure solenoid alone. The Nissan part number for the solenoid pack is 31940-41X04.
The Nissan solenoid pack is not completely compatible with the Mazda unit. Due to the expense of the Mazda solenoid pack it may be a better choice to replace only the line pressure solenoid. The Nissan line pressure solenoid is fully compatible with the Mazda unit. The part number for the Nissan line pressure solenoid is 31940-41X01.
Note
The line pressure solenoid should be replaced during rebuild on units with more than 50,000 miles.