2004 XC70 P0733 Gear 3 incorrect ratio Topic is solved

[shiloh51933]

My wife was driving the 2004 XC70 for a couple of hours, then the 2-3 upshift flares. It's got no 3rd gear at all but it will bypass 3rd if I use the sport shift. I met up with her and drove it home. There's no flashing lights, NO red triangle, no CEL. No messages on message screen...nothing. I hooked up my scanner and got the generic code p0733 Gear 3 Incorrect Gear Ratio. ATD fluid level reading was at the L marker, so I added a little. I've done numerous drain/fills over the years. Any suggestions or questions? Every other gear works including reverse.

One thing you might check with the servo cover off is the condition of the 3rd gear band. To do this I use a rod through the servo pin hole to compress the band and marked the rod when the band was fully compressed. I measured 93mm to the edge of the trans case at the servo cover opening, see photo. To check servo travel I also measured the length of the servo pin with the cover, which measured 84mm.
There a couple of adjustment needed to get the final travel of the servo pin.
You have to subtract 6mm from the measured mark on the rod so in my case 93mm - 6mm = 87mm. The 6mm is from the outside of the transmission case to the inside of the snap ring hold the servo cover in place. The total length of the servo pin with cover is between the tip of the pin and outside edge of the servo cover. The outside edge of the servo cover when installed is the inside edge of the snap ring.
There's also 2mm of compression on the servo pin when it's applied due to a cushion spring so this 2mm needs to be subtracted from the servo pin and cover measurement, in my case 84mm - 2mm = 82mm. The servo pin travel I calculated is 87mm-82mm = 5mm. The spec is 5.76mm to 6.76mm according to the ATSG manual I have. My measurements are probably not as precise as they could be and compressing the band with the rod is not the same force as the servo pressure compressing the band but the measurements did give me a good idea the servo travel wasn't horribly out of spec.

I think if you have a badly worn 3rd gear band you'll see a measurement noticeably larger than the 93mm I measured. There are differently length servo pins to bring the servo pin travel into spec and I think this may be option assuming the problem is not the servo cover or the anchor bolt was removed or a badly worn out 3rd gear band. How long has there been a 2-3 flare? Mark at full compression.jpgUsing rod to compress band.JPGLenght of servo pin and cover.JPG

There has never been a 2-3 flare, I wouldn't call it a flare...atleast not as I understand a flare. It's as if 3rd gear is no longer their at all and if you moving quickly the computer will bypass it eventually for 4th. There's no slipping at all, it's just not there. I think the band is shot or the solenoid is bad.

[shiloh51933]

I've had the brake booster sensor cause erratic shifting and hard down shifting...I mean slamming down. I replaced the brake booster sensor after diagnosis and she shifted perfectly for years after.