After emergency services arrived at the crash scene, Ms Nichol was taken to hospital but died from her injuries.
Her front seat passenger and the driver of the Nissan were badly hurt following the incident.
Lynn was later questioned by police and insisted he could not remember anything before the crash.
An allegation that he had fallen asleep at the wheel was deleted from the charge prior to his guilty plea being accepted.
Victoria Dow, defending, had asked for Lynn’s bail to be continued to sort out matters relating to the family business.
Lynn is a director of the firm – his role being in groundwork, fire protection and health and safety.
However, judge Lord Clark remanded him in custody pending sentencing on 30 October in Edinburgh.
He said the matter was a “serious crime with devastating and catastrophic consequences”.
