On top of the fact that my XJR had a C1175 (left rear wheel speed sensor) code AND the "ABS/Traction Unavailable" messages, it ALSO has a P0780 (shift error) code.

I realize that the transmission may be shot, and if so, I am willing to accept that. However, I'd like to describe some of the symptoms, and see if you guys think it might be something simpler like the Valve Body.

Last Year:
The guy I bought it from said that it was starting to hesitate between shifts. He continued to drive it. One day, he was in 3rd gear going through an intersection when a driver in the cross traffic looked like they were going to hit him. He stepped on the gas to get out of harms way. The trans didn't want to downshift, and after flooring the gas pedal the trans finally shifted with a loud "Clunk". After that point it wouldn't shift out of 1st gear. He parked it in his garage and didn't drive it after that point.

Last week:
I bought it. He said he could deliver it to my house on a flatbed trailer. He was assuming he would have to push it out of his garage and onto the trailer, but surprisingly he was able to put it in reverse, drive it out of his garage, put it into 1st gear, and drive it onto the trailer. After trailering it the 45 minutes to my house, he was able to put it into reverse and back it into my garage. When in park there was a noticable "rattle" type of sound, but as soon as it shifted into 1st or reverse this rattle went away.

Last night:
After cleaning my rear speed sensor, I wanted to drive around the block in 1st gear to get up to 12mph and test whether my cleaning had fixed the C1175 error code. However, I was unable to shift out of park (either into reverse or 1st gear).

So... does this sound familiar to anyone? I've got the JTIS instructions about how to go about removing the Valve Body, but is there any diagnostics that I could try doing either on the TCM or valves?... or does this sound like clutches and gears are completely destroyed?

Thanks for any input! You guys are livesavers!

-Caleb

 

Are you asking about your 1999 XJR with W5A 580 (722.6) gearbox??????????????????

bob gauff

 

Yup... exactly.

 

A full vehicle scan would help in the diagnosis but most people will not go to someone with the full diagnostic computer like the dealer or shop with dealer level computer.
("it costs too much" or "it's too far")

The Mercedes gearbox is fairly bulletproof but.....................

A 'trannie' shop that is good with Mercedes gearboxes might have more info.

bob gauff

 

Is there anything I can test or troubleshoot at home myself without taking it to a dealer for a full scan?

 

I did a bit of searching and came across this image, which appears to show the resistance of healthy solenoids in a 722.6 valve body:



I also found a nice exploded view of the Valve Body on the sonnax website >>> Here <<<

But then I had another thought...

I am only able to read OBC codes, and therefore was only able to read the P0780 "Shift Error" code. However, there are also error codes stored in the Transmission Control Module (TCM) that could be read with a more expensive reader right?

And even if I am able to figure out the problem on my own... if my car currently has error codes stored in the TCM, then even after I put a working transmission back in (rebuilt original OR salvage yard replacement), it still won't work until those TCM codes are cleared right?