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Home >> GMC >> 1989 >> Forward Control 4.8 T, Standard >> Repair and Diagnosis >> Engine Performance >> System >> CCC TBI Tests W/Codes >> Diagnostic Charts >> Map Output Check >> Circuit Description
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Circuit Description

The MAP sensor measures manifold pressure (vacuum) and sends that signal to the ECM. The MAP sensor is mainly used for fuel calculation, when ECM is running in the throttle body back-up mode.

The MAP sensor is also used to determine barometric pressure and to help calculate fuel delivery.