Auto Service Professional

JUN 2018

Magazine for the auto service professional

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50 A S P J u n e 2 018 S R S D i a g n o s t i c s T By Jeff Taylor The Supplemental Restraint System (SRS); or in GM jargon SIR (supplemental inflatable restraint system) uses more components than just airbags: modules, crash sensors, seat weight and position sensors, seat belt switches, warning lights and pre-tensioning devices are all used to protect and enhance the safety of the driver and passengers. But these components fall into categories similar to an engine management system. ere are inputs, outputs and control modules. And similar to an engine management diagnostic, each area will require certain tools and proce- dures for a proper repair. With the proper up-to-date information, a good scan tool and a few other pieces of test equipment, an SRS repair or diagnostic can be straightforward and may not require a factory scan tool or test equipment to be performed suc- cessfully. Common SRS input issues Many input system issues can normally be diag- nosed with an up-to-date non-factory scanner to retrieve and clear codes aer a repair, along with a volt ohm meter for diagnostics. 2007 to 2014 GM C/K trucks suffer from a corrosion issue in their front crash sensors or front end sensors (FES). is issue will usually cause the SRS light to flash seven times and stay on. ere are several codes that can accompany an FES issue or failure, so it is important to pay attention to the sub digits of the trouble code for proper diagnostics. If the scanner reveals a B0084-00 right front impact sensor, this should lead you to the in- spection of the right side sensor. But the suffix for the B0084 code could be 0F, 39, 3A or 71, so it's important to look at the code completely. ese trucks usually have a skid shield under the radiator that will need to be removed to Service can be intimidating, but it doesn't need to be When it comes to diagnosing an air bag system, some techs will shy away from getting involved. e fact that the system will contain one or more pyrotechnical devices in the form of an airbag or seat belt pretensioner can raise some eyebrows. However, with the proper up-to-date information, an SRS repair or diagnostic can be straightforward and may not require a factory scan tool or test equipment to be performed successfully. SRS diagnostics and repairs In addition to heightened awareness due to OEM recalls, any illumination of the airbag MIL is cause for concern.

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