Clearing ECM Trouble codes
I've got a '91 GMC 1 ton dually 4 wheel drive. 454 tbi. Having some drivability issues, so wanted to check and clear trouble codes. There were 3 stored codes, but when I try to clear them, one code remains. Code 34. Map sensor. The other codes cleared, just not the 34. Even after leaving battery disconnected fo 10+ minutes, the check engine light comes on imediately at start up. Even when I checked the code bank BEFORE starting the engine, code 34 is present. Is this an ECM issue? Another strange thing... With the engine running, I disconnected the Idle air circuit, the throttle positioning sensor, the map sensor, and even the EGR all at the same time, and the engine ran the same. Gotta be a computer issue?
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