GM Releases Position Statement on Pre- and Post-Repair Scans

Oct. 21, 2016

Oct. 21, 2016General Motors Company has issued a position statement for the collision repair industry directing technicians to scan damaged vehicles for diagnostic trouble codes (DTCs) both before and after repairs.

GM’s goal is to ensure that all necessary repairs are diagnosed during the estimate process, and that vehicles are returned to customers in pre-crash condition. Testing is especially critical when safety systems are impacted.

“Even minor body damage or glass replacement may result in damage to one or more safety-related systems on the vehicle,” said John Eck, collision manager, GM Customer Care and Aftersales. “Any action that results in loss of battery-supplied voltage and disconnection of electrical circuits requires that the vehicle be tested post-repair to ensure proper electrical function.”

GM stated that the method to correctly identify vehicle diagnostic trouble codes (DTCs) is by using the appropriate GM diagnostic software: GDS2 or Tech2/Tech2Win, each of which can scan a vehicle for all DTCs in one operation. GM diagnostic software is supported by one of the GM-approved diagnostic scan tools (MDI or a J2534 device). GM does not recommend the use of other scan tools and cannot guarantee their accuracy.

Many safety and security-related components, sensors and Electronic Control Units (ECUs) require calibration and/or “learns” when replaced, Eck stresses. These systems must be repaired according to the corresponding GM repair procedures.

“Technicians who follow proper pre- and post-repair scanning procedures have an edge when it comes to customer satisfaction because dashboard lights can’t tell you everything that’s going on with a vehicle’s electronics,” Eck said. “With pre- and post-scans, techs will start with the right diagnosis and right parts out of the gate, they’ll reduce repair cycle times and they should see fewer follow-up visits. More importantly, the scans will help ensure that the vehicle and its safety systems are returned to their pre-crash conditions.”

All of GM’s position statements can be downloaded at