4R70W questions.. no 1st or 4th. MLPS?

The_Ghost

Registered User
I have a 4R70W that is not using 1st and 4th gear, and stopped using them after a car-wash with the undercarriage wash.

I have another 4R70W in a different car that behaved similarly when the MLPS was wayyyyyy out of whack (I have since re-adjusted it and 1st and 4th gears came back)

It is obviously some kind of electrical issue, what could possibly get wet that would make the trans start ignoring 1st and 4th gears?

Just trying to do some investigating and figure out what's going on.

Thanks,
Ghost
 
What Year SC do you have?

As the Title asks, the 94 SC had a lousy gasket on the MLPS and the 95 fixed that issue. I have a 95 that I think has an older MLPS in it because the tranny starts to neutral when going into 3rd gear sometimes after going through a puddle, or when it gets wet. Check out the MLPS and see if you see a red gasket sticking out around the center of the housing where it is screwed together. If you don't see one then you have the old one on there. Change it and see if it doesn't fix the issue.

Not a cheap itme though!!

Smitty
 
Both first and 4th gears require shift solenoid 1 to be on. If it is stuck off or not getting signal you will not have either of those gears. Here is a electrical schematic of how the shift solenoids work.
........ SS1 ............ SS2
1st.....on .............. off

2nd....off ..............off

3rd.....off ............. on

4th ....on...............on
 
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