Tag: valve body

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2001-2007 AW55-50SN Valve Body Re-assembly

MVS Forums Contributor Mike (precopster) shares a video he made of his valve body re-assembly, and much more about 2001-2007 (in North America, 2000-2008 in Australia) Volvo AW55-50SN transmissions.

If you have undiagnosed banging noises on downshifts, and RPM flares, you would likely benefit from the information in this topic, even if you end up having the work done.

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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.