ECM Code EO34, Map Signal Too High: Action:

ECM turns on SERVICE ENGINE SOON light. ECM uses a substitute barometric sensor value of 92 kPa and looks up a substitute MAP sensor value from a MAP versus RPM table, when throttle switch is closed.

The MAP sensor output voltage is a D voltage that varies with MAP. As MAP decreases, voltage on circuit No. 432 decreases (low engine load and high engine vacuum). As MAP increases, voltage on circuit No. 432 increases (high engine load and low engine vacuum). The ECM uses MAP sensor reading as an indicator of engine load. Low MAP readings mean low engine load, and high MAP readings mean high engine load. Code EO34 is designed to set when ECM detects a MAP sensor signal that is much too high for closed throttle test conditions.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test Number 1) MAP at idle should be 30-50 kPa, depending on engine load. BARO pressure should be 85-105 kPa, depending upon altitude.

Test Number 2) Check for vacuum at MAP sensor hose with vacuum gauge. At idle, typical vacuum readings are 14-20 in. Hg, depending on engine load.

Test Number 3) This checks for faulty MAP sensor vacuum supply or MAP sensor circuitry.

Test Number 4) Checks for sensor ground open from sensor to ECM.

Test Number 5) Checks for short to voltage on sensor signal circuit No. 432.

Test Number 6) Fault is at ECM connector or ECM. See CHART C1, ECM REPLACEMENT CHECK before ECM is replaced.