S-Type 2001, 3.0, auto, gearbox issues....

Symptoms at the beginning;

P0731: 1st gear incorrect ratio
P0734: 4th gear incorrect ratio

Would not select drive, had to select 4th or 3rd to get a gear.
Slow to engage drive.
Seemed to be taking off in 2nd, but under full throttle ~4500rpm it jumped back to 1st
When cold would seem to get 4th at too low a speed & the car would bog down (or maybe 5th?) & it would thump & jump back up a gear.
Shifts were generally jerky, with a regular thump.
Gearbox Fault on dash, message cleared with reset button, but would return again later.

Actions taken;

New shifter cable, adjusted correctly (AFAIK)
Drained the trans fluid & refilled with Mercon V
Cleared codes, reflashed ECU

Still seems to be taking off in 2nd, & under full throttle ~4500rpm it jumps back to 1st.
Will get a gear with the shifter in D, but slow to engage, 2-3 seconds, reverse selection is immediate
Bogging down into a higher gear less, but still occaisionally doing it.
Shifts are much better, but still a bit harsh & thumpy.
Manually selecting gears with the J-gate takes several seconds to get the gear
Still getting Gearbox Fault on dash, message cleared with reset button, but returns again.

Now, checking the codes i'm only getting the P0731 (1st gear incorrect ratio), the P0734 has not returned....

If it was the 4-3 spring I would be getting the P0734.

I'm willing to chuck a rebuild kit & shift kit into the valve body, change springs etc along with new filter, gaskets & fluid.

But....

I have not found anyone who's had the P0731 or incorrect ratio on 1st gear, not in a Jag, not in a Lincoln, not in a Ford Exploder or F-Truck....

So you could understand i'm a little hesitant to drop $500 on the rebuild if it won't solve the 1st gear issue....

Any suggestions?

EDIT

Also worth mentioning, the other DTC's in the car are all relating to Canbus short or open, but I thought the wiring issue under the bumper was only on the later models >2002.5MY???

 

I also think the fault for the harness behind front bumper is 2003-on.

I think the jag OE diagnostics can command the various solenoids but sorry don't know if that is useful for this kind of thing.

Er... what CANbus??? (& what codes?)

I expect you've seen this PDF.

 

Yep seen that PDF, doesn't make things any clearer for me.

The only mention of losing 1st gear, also includes 4th & 5th, as well as throwing up other codes. The P0731 alone without any others is, just not explained...

For Example, Solenoid failures in that document always include 1st, 4th & 5th together...

OK not "CANbus" but SCP (J1850) Communications bus fault.

I didn't screenshot them after they came back, but basically same fault in the Instrument Pack, Message Center Control Module, Drivers Door Module, General Electronics Control Module, Rear Electronic Control Module.

Also, the Restraints Control Module is incommunicado; ERR 0xc shown instead of codes....

I don't think it's related to the transmission issues...

 

How many miles?

Are you aware of case bore wear on the Ford tranny? Happens with high miles usually.
Has the valve body been changed?
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230'000kms / 143'000mi, as far as I know the valve body is all original, the trans fluid that came out was black so i'd say it had never been changed either.

I read a bit about bore wear, but frankly i'm a dunce when it comes to transmissions...

 

5R55N sevice manual here if its any use to you

http://www.mediafire.com/view/dz33ey...ice_manual.pdf


alldata info on p code

 

I have a 2003 Lincoln LS and it took several try's to fix some shifting problems but in the end the dealer had to replace the entire valve body to get it shifting right. But it's been very good since then and that was over 50K miles ago.

The case bore is mileage related and may or may not be causing problems. From you fluid description I would keep changing fluid until it looked good and clean. Then attack the valve body.

FORD'S FOUR VERSIONS OF 5R55

Symptoms & Solution - Ford Servo Bore Transmission Fix Solution

I really like Sonnax as they have a fix for just about all the transmissions problems.

Overdrive & Intermediate Servo Pin Bore Sleeve Kit - 56361J-01K - Sonnax
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Well they mention possible causes of Shift Solenoid, Pressure Solenoid or Crank Sensor failure, BUT those would be accompanied by DTC's for those faults.

The last suggestion is "transmission mechanical failure" which is seeming more & more likely...

 

Cambo, did you resolve this issue? Do you remember what did it for you? THanks