1991 C3500 Diagnostic Code Pattern: 2-Flash, Pause, 8-Flash, Pause, 1-Flash, Pause, 3-Flash - What Does This Mean?
This is my first time posting on the forum, so I may be in the wrong section. I'm trying to interpret a diagnostic code pattern from my 1991 C3500. The code sequence flashes as follows: 2 flashes, pause; then 8 flashes, pause; then 1 flash, pause; followed by 8 flashes, pause; and finally 3 flashes. I would like to know what this specific code sequence means in terms of engine or vehicle system diagnostics. Any clarification on the meaning of these codes—especially regarding the ECM or engine control module—is greatly appreciated.
The 8th character of your VIN is important to identify your specific engine and ECM configuration. Could you also describe the symptoms you're experiencing? This would help pinpoint whether the issue is related to the engine, transmission, or another system. Additionally, double-check your code reading—some sources suggest the first code should be 12; the others may actually represent transmission-related codes rather than engine issues.