A/T - Early TCC Engagement, Stumble, Detonation

Number 83-I-51 Section 6 Date 03/83
Subject: EARLY TCC ENGAGEMENT - ALL VEHICLES USING AN ECM CONTROLLED TCC
Vehicles exhibiting an early TCC engagement causing a stumbling or detonating condition may be due to grease or dirt on the two reflective bars of the speedometer head that serve as reflective panels for the VSS signal. Any foreign material on these bars will interfere with their reflective properties thereby generating a false vehicle speed signal.

The reflective bars should be thoroughly cleaned if this condition is found.

All other normal diagnostic procedures should be followed before suspecting this condition.