P1788 Coast Clutch Solenoid Open Circuit (from FORScan)

[02LincLS]

Pressure control solenoid B open circuit.

I went to merge on the highway from about a 10 mph roll and put the shifter into first and got on the gas. I've never had the car get confused before, but I think it MAY HAVE only gone down to 2nd. Sensing it didn't do exactly what I wanted, I put it into D4 quickly so that it didn't have to worry about any other inputs I was giving it. However, the first upshift it made while getting up to speed felt strange, almost light a slight bog or bind. I immediately got off the gas altogether until it sorted itself out which it did. I eased carefully back into the throttle but I got the E check transmission. There is no slipping, and all gears work. Going into drive and reverse seem fine, theres just firm upshifts, in alignment with another thread stating that the car is upshifting with full pressure. Its not bark the tires hard, but I'm obviously taking it easy until I get this sorted. Downshifts are fine.

There's only a few threads on this here, and only 2 have slightly helpful info. One of them links to the jag forum. He went to a dealer and they diagnosed a specific solenoid. Sadly, he gave no part number. He did also get a gasket, and filter, so does this mean this item is installed in the valve body? Is this what he bought... "shift solenoid" ?

Anyone with a service manual have more info about what it will take for me to lose the E? Thanks for any help!

 

[joegr]

Jaguar got a different transmissions. (2nd gen, anyway.)
So what specific OBD-II code(s) do you have?
All the transmission solenoids in the LS transmission are in one assembly. They can't be changed separately.

 

[joegr]

P1788 - Solenoid assembly, wiring, or PCM. (At least those should be the possibilities.)

 

[02LincLS]

Thanks for the fast reply. I saw your name replying to someone else on the interwebz. 02 V8. P1788 is the only code.
I'll look for damaged wiring first but not holding my breath to get out of this that easy. If it is the solenoid, is this the part (highlighted) shift and throttle pressure solenoid?
I love this car, but depending on what this cost/entails for labor, it very sadly may be time to part with it.

edit:here's the jag link if its of any benefit (his car was a 2000) P1788 Transmission problem - Jaguar Forums - Jaguar Enthusiasts Forum

 

[joegr]

If it is the solenoid assembly...

Then you need XW4Z-7G391-AB if your production date is before 07/2001, or XW4Z-7G391-AC if after that. Either way, the part is about $263. I don't blame you for not wanting to DIY this. It is a messy job without a lift. If you get it done somewhere, it will probably be around $700 after labor, fluid, filter, and the assembly. I would add another $100 or so to have the valve body rebuilt.

 

[02LincLS]

Exactly, still need to rule out wiring first.

I used the VIN to find the solenoid assy and confirm that part number matches what I came up with (April '02 is the build date).

I was afraid of a labor cost like that. I did find a new assy for $250. Maybe the best move is attempt to pull the valve body myself. And yes it sure will suck in the driveway. If there's a documented procedure, that sure would help. I think I saw a thread with pics on these forums years ago where the guy rebuilt one- I'll try to dig that up. One thing that comes to mind is "don't tip the assembly and lose the tiny balls". I'm obviously a little hesitant about doing it myself but an official procedure combined with that how-to thread would help with my apprehension.

For now, I'm using another car. Is there other detriment to driving it this way, aside from the increase shock on the upshifts from the apparent over pressure?

 

[heyjewel]

Exactly, still need to rule out wiring first.

I used the VIN to find the solenoid assy and confirm that part number matches what I came up with (April '02 is the build date).

I was afraid of a labor cost like that. I did find a new assy for $250. Maybe the best move is attempt to pull the valve body myself. And yes it sure will suck in the driveway. If there's a documented procedure, that sure would help. I think I saw a thread with pics on these forums years ago where the guy rebuilt one- I'll try to dig that up. One thing that comes to mind is "don't tip the assembly and lose the tiny balls". I'm obviously a little hesitant about doing it myself but an official procedure combined with that how-to thread would help with my apprehension.

For now, I'm using another car. Is there other detriment to driving it this way, aside from the increase shock on the upshifts from the apparent over pressure?

I followed that procedure, I think you'll find it if you search on 5R55N problems or something like that. Writer was Mike something IIRC. There's also a good procedure in the DVD manual.
Anyway the mess won't be as bad if u can figure a way to catch all the tranny fluid. There'll be lots left in the thing even after you drain the pan with the plug. And when u pull the pan more comes and then pull the filter out here comes more. And it will drip from everywhere while you're working on it.
Two things here - if you're just doing the solenoid assembly you dont have to worry about losing your balls - that may happen if you remove the valve body. But you do not need to remove it for this job. Solenoid replace requires only one difficult maneuver - you must unscrew a bolt that's on top of the transmission out of sight. You can locate it by feel. You will almost certainly need a 10mm ratcheting wrench to remove the bolt. The bolt is captured on the wire harness connector and the connector is what you need to remove Good luck.

 

[02LincLS]

Found it, thanks! Solenoid R&R - 2002 Lincoln LS V8 (5R55N)

When you say top, is it on the side, but the top face? And is that the bolt for the electrical connector?
here is the not-so-clear view from the N procedure...

 

[heyjewel]

Found it, thanks! Solenoid R&R - 2002 Lincoln LS V8 (5R55N)

When you say top, is it on the side, but the top face? And is that the bolt for the electrical connector?
This is a pic of the 5r55s from an explorer which ironically enough, is referenced in that link above.
View attachment 828566304
and here is the not-so-clear view from the N procedure...
View attachment 828566305

Nope, it is on the top of the transmission and holds the solenoid body in and provides the transmission wiring connection. You will have a perfect idea of where it is when you are looking at the solenoid pak. It is right above the connector. Gotta reach around to the top to access it. That wrench would be good. No need to cut one though, I bought a set of about 6 ratcheting wrenches with length proportional to opening size. My 10mm is about 4 or 5 inches long. Fits well.