Instruction Manual / Service Manual for Volvo 850 T5 M reg

https://big-manuals.com/products/1997-volvo-850-service-repair-manual

All kinds of workshop and services manuals are available here. May be this could help for you

Update software

sounds like your power steering is failing, get it checked at a garage asap, steering is important when going fast :), probably needs steering wheel taken apart and power steering components checked for wear/damage.

It's your abs control module. Remove your abs control module and send it out to be rebuilt. It should cost you less than $100. Check out the offerings on Ebay.

This is for a 98 T5, but it should be close enough. http://www.matthewsvolvosite.com/forums/viewtopic.php?p=93956#p93956

You can get one from your local volvo dealer. they are able to order them from parts support

This is just a reminder that you need to have the vehicle serviced. It comes on every 5,000 miles or so. Here are instructions on how to reset the light - http://www.matthewsvolvosite.com/2008/12/reset-service-light-volvo-850-s70-v70-c70-xc70/

possible traction control turned off. try some switches to the right of the steering wheel and see if it comes on/off.

You need a fitting kit.

It is better to buy the haynes or Chilton manual and follow the instructions step by step.

You find the manual here
Repair Manuals from Haynes

to give you an idea, here are the instructions for S40.

Its dirty, rusted or the rivets are coming loose. Open up clean and spray a little oil. If that does not help. Take a hammer and after removing the whole lock resecure the rivets with the hammer.
IT MAY ALSO BE THAT YOUR BATTERY IS NOT STRONG ENOUGH ANYMORE AND SHOULD BE CHECKED.