Troubleshooting 2001 and 2002 Auto Transmissions

Neutral control bump is the result of the pulsed solenoids getting bore wear and the pulsed signal outputted by TCM is not really getting the pressure regulation desired. There is no pressure sensor so the TCM infers pressure through its adaptive shift control, i.e., if the shift is completed within the target time with X% solenoid signal then .5X% should be the right signal to reduce clutch apply pressure to let it slip during N control and not have slam engagement when brake is released. With worn solenoid or valve body spool valve bores the pressure with that reduced signal is not what is inferred via software.

Project: Advanced Troubleshooting of 2001 and 2002 Auto Transmissions

Transmissions

carboncow ask:

“We’ll in the last two weeks we repaired a bad haldex on my XC70, bad exhaust flange at the turbo and new end links…I guess we were due for more catastrophe!

The wive’s 2001 (150K’ish miles) just tossed up the “transmission service required” on screen. Of course she forgot to tell me this happened yesterday so I didn’t have time to pull codes with the Vida…so my inquiry is a bit premature but I wanted to get comments.

The transmission still drives (no hard shifts) as fine as it has for the last two years including the two following issues:

  1. backup has always required quite a few RPM like there is no pressure
  2. the neutral stop bump from a stop has always been there and the wife has done fine with just taking her foot of the brake before gunning the gas.
What is the common failure as I see a few guys talking about replacing something accessible from the tranny, or should I just count on rebuild or junking it at this pont!”
jimmy57 says:

“There are two gear ratio ranges used in the 5 speeds, 55-50 do not use as low geared reverse with reverse being taller than 1st and would make engine reach higher revs closer to TC stall speed on a grade. 55-51 gearboxes have a lower geared reverse that is lower geared (higher numerical, always confusing…) and backs up with less effort than it goes forward. I suspect you have 55-50 in the XC and the reverse sensation is normal. Pressure as regards to reverse is not a grey area thing…”

Transmission service required, yes it’s a 2001…

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Last Updated on August 19, 2020

2 Comments

I was looking to buying a 2005 xc90 Volvo, but reading all this comments is really discouraging me and am sad because I really like the car but not to the extent of burning an unnecessary huge hole in my pocket.

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