Steering wheel power assist became inoperable when turning into a store parking space. If the steering assist had failed while at higher speed and/or in other conditions the results may have resulted in a potentially life threatening situation. There was no prior messages or symptoms the problem prior to the event. It was discovered that the GM service bulletin 23-NA-201 includes my vehicle as prone to the failure due to corrosion of the body grounding straps. The vehicle trouble lights also acted in accordance to the description in that same service bulletin. The grounding straps were found to be badly corroded to the point of fragility. Grounding was replaced and the vehicle trouble lamp display returned to the normal. The steering assist in the vehicle then returned to normal operation with no further occurrences.