Kamran Hussain fitted the lights to his windscreen and is alleged to have used them to stop another driver in Manchester Road, Huddersfield in April, last year.
The volunteer officer, who was on duty at the time, said he as a police officer, but the other driver was not convinced and called the police.
Officers from the West Yorkshire force arrived at the scene and arrested Mr Hussain on suspicion of impersonating a police officer.
When further investigations revealed he was a special constable, he was then arrested on suspicion of misconduct in a public office.
Mr Hussain pleaded guilty to using a vehicle on a road fitted with a blue warning beacon when he appeared before the courts in September, last year.
He was fined £119 and also ordered to pay court costs of £85.
A misconduct hearing into Mr Hussain's actions will take place at the force's headquarters in Wakefield today.
In a statement the force said: "It is alleged that ex-special constable Hussain has breached the Standards of Professional Behaviour in relation to: honesty and integrity, authority respect and courtesy and discreditable conduct."
Special constables have the same powers as regular police constables once they complete their training and spend around four hours a week working alongside front-line officers.