ECM Code EO22 - Open TPS Circuit: Notes

TEST CONDITIONS: Engine RPM is greater than or equal to 600.

FAILURE CONDITIONS: TPS value is less than -5 degrees (TPS parameter reads -10 to -6 degrees) for 1.5 seconds.

ACTION: ECM turns on "ENGINE CONTROL SYSTEM" light. ECM commands BCM to display "SERVICE SOON" message on CCDIC panel. ECM uses 12 degrees for TPS value with ISC throttle switch wide open, and 6 degrees for TPS value when ISC throttle switch closes. ECM stops using TPS to control ISC motor (it uses RPM for all ISC calculations).

The TPS is a 3-wire sensor receiving a 5-volt reference input from ECM over circuit No. 474, and a reference ground from ECM over circuit No. 476. The TPS sensor sends a sensor output signal over circuit No. 417 to the ECM.

The sensor output signal is a DC voltage that varies with throttle angle, the TPS signal voltage is low (about .5 volts at minimum air setting). At high throttle angles, the TPS signal voltage is high (about 4.5 volts at wide open throttle).

Code EO22 is set when the ECM sees a that throttle angle is out of limits (low TPS voltage) with engine running at idle or faster. Code is designed to detect a TPS signal, over circuit No. 417, open to ECM pin "D7".

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

Jumper 5 volts to TPS signal to see if ECM parameter will respond to high signal voltage on TPS inputs (circuit No. 417).
Checks for an open/shorted TPS reference circuit.
Checks for a grounded TPS signal (circuit No. 417).
Fault is most likely at ECM connector or ECM. See CHART C1 - ECM REPLACEMENT CHECK before replacing ECM.