Scanning GMC check engine codes is necessary to diagnose the problem that has occurred in a GMC car’s systems. GMC is a subsidiary of General Motors that focuses on manufacturing trucks, buses, vans, and utility vehicles. Like other car manufacturers GMC vehicles use on-board diagnostic (OBD) system that allows the diagnosis of problems when the check engine light on the dashboard turns on. A static light signifies trivial problems whereas a flashing light generally indicates more serious problems.
What Are GMC Check Engine Codes?
There are two types of GMC check engine codes, that is depending on the OBD system used in the vehicle. In the old OBD system before 1996, the codes consist of a two-digit number that can be retrieved either by using a scanner or by reading the flashing pattern of the check engine light. For example, a pattern of FLASH-FLASH-PAUSE-FLASH is equal to code 21. In a GMC OBD system, it signifies a problem with TPS circuit.
In the new OBD2 system, which becomes the standard since 1996, the code consists of 5 characters starting with an alphabet, which indicates the location of the problem, and followed by a four-digit number, which identifies the nature of the problem. There are four alphabet letters used by the code: P for powertrain, B for body, C for chassis, and U for network. The code P1801, for instance, signifies a problem with the performance selector switch. Read the section below to learn more about how to retrieve codes from the old OBD system.
GMC Check Engine Codes Scanning with and without a Scanner
You can scan GMC check engine codes using two alternative ways, depending on the OBD technology that is used in your vehicle. Older vehicles, which are manufactured before 1996, use OBD system that doesn’t always require the use of a scan tool for scanning purpose. By attaching a jumper between the A and B terminals on the Data Link Connector (DLC) and then turning on the ignition, you can easily retrieve the check engine codes by counting the flashes on the check engine light.
The second way to scan GMC check engine codes is by using a scanner. There are several scenarios in which a scanner is needed. Firstly, some GMC vehicles that are manufactured before 1996 use Data Link Connector that doesn’t include a B terminal. Using a jumper is thus not possible on these models, so a scanner is needed to retrieve the codes. Secondly, there are some GMC vehicles that use OBD system and Data Link Connector that does have both A and B terminals, but a scanner is still needed to retrieve check engine codes. Thirdly, since 1996, OBDII or OBD2 has become a mandatory protocol for all vehicles manufactured in the United States and/or to be sold in the United States, including GMC vehicles. To retrieve GMC check engine codes from OBD2 system, a scanner is always needed.
Can All Scanners Read GMC Check Engine Codes?
All OBD2 scanners work using the same procedure; however, because GMC check engine codes include not only generic codes that GM shares with other vehicle manufacturers, but also manufacturer-specific codes that are exclusive to GMC vehicles, be sure to choose a scanner that has the capability to read and interpret GMC-specific check engine codes.