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So what happens in reverse if solenoid #1 does not engage? Why does solenoid number 1 engage in R, if it is strictly hydraulic in R?
The No. 3 valve body solenoid operates in reverse. When No.
3
valve body solenoid is de-energized, solenoid plunger moves away from
seat. This opens the drain port and releases line pressure. When No.
3
valve body solenoid is energized, the plunger closes the drain port.
NOTE:
For valve body solenoid usage, see VALVE BODY SOLENOID
APPLICATION table.
VALVE BODY SOLENOID APPLICATION (1)
Shift Lever No. 1 No.
2
Position Solenoid Solenoid
"D" (Drive)
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
3rd Gear .................. OFF .................... ON
4th Gear .................. OFF ................... OFF
"3"
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
3rd Gear .................. OFF .................... ON
"1-2"
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
"R" (Reverse) .............. ON .................... OFF
"N" Or "P" ................. ON .................... OFF
(1) - Valve body contains 3 valve body solenoids. See
Fig. 2. No. 1 and 2 valve body solenoids are used
for controlling transmission shifts. No. 3 valve
body solenoid is used for torque converter
lock-up only.
1988 Jeep Cherokee AUTOMATIC TRANSMISSIONS Aisin Warner 4 Electronic Diagnosis
If you compare the settings, it looks like that's more a factor of TCU design and user comfort. They have the same solenoid selections listed for N, P, R, and 1st gear (in 1-2, 3, or overdrive.) My bet - the TCU leaves the solenoids in 1st gear for N/P/R so you won't feel a shift lag or lurch when you drop it in drive like you would if it was sitting in OD while in N/P/R.
I have one hanging on the wall in my workshop at home, but looking at all those passages makes me go :wow:
Reading through the FSM section with the hydraulic schematics for the AW4 will probably be way easier to understand, and even those are pretty confusing.
The last auto trans I had apart was a 4sp electronic front wheel drive job from a Focus.
needless to say I'm done fixing automatic transmissions, if it dies it's getting a 5 spd swap.
note the jar of random bits from the valvebody on the right.
Good times reassembling that.
If you compare the settings, it looks like that's more a factor of TCU design and user comfort. They have the same solenoid selections listed for N, P, R, and 1st gear (in 1-2, 3, or overdrive.) My bet - the TCU leaves the solenoids in 1st gear for N/P/R so you won't feel a shift lag or lurch when you drop it in drive like you would if it was sitting in OD while in N/P/R.
Bailing wire and bubble gum would also be a nice addition to your tool bag. LOL