E022
TEST CONDITIONS
1. RPM equal to or greater than 600.
FAILURE CONDITIONS
TPS value less than or equal to 1.3 degrees for 0.7 seconds.
ACTION TAKEN
1. ECM turns on "Engine Control System Fault" telltale;
2. ECM commands BCM to display "Service Soon" message on the Driver Information Center (DIC);
3. ECM disables the Viscous Converter Clutch;
4. ECM sets TPS equal to 13 degree when the Throttle Switch is open and 6 degrees when the Throttle Switch is closed.
DESCRIPTION
The Throttle Position Sensor (TPS) is a "3-wire" sensor or potentiometer. A 5 volt reference is provided at Pin C on CKT 474 and ground is provided at Pin B on CKT 1076. The TPS signal circuit (Pin A CKT 417) varies between ground and 5 volts based on the position of the throttle plates. At low throttle angle, the TPS signal voltage is low (about 0.5 volts at minimum air setting) and at high throttle angles, and TPS signal voltage is high (about 4.5 volts at WOT). The ECM uses TPS information to determine fueling needs (WOT enrichment, acceleration enrichment).
Code EO22 is set when the ECM receives a low TPS voltage (low throttle angle) at high engine RPM. Possible causes of Code EO22 are:
1. TPS signal (CKT 417) open between TPS and ECM;
2. TPS signal (CKT 417) shorted to ground.
Notes on Fault Tree
1. Checking to see if the ECM will respond to high signal voltage on TPS signal (CKT 417).
2. Checking for TPS 5 volt reference (CKT 474) open or shorted to ground.
3. Checking for TPS signal (CKT 417) shorted to ground.
4. Fault is most likely at ECM connector or ECM. Before replacing ECM, perform "ECM Replacement Check," Chart C-1. Chart C-1 Vehicle Will Not Enter Diagnostics
NOTE ON INTERMITTENTS
If a Code EO22 is intermittent, manipulate TPS connector, TPS wiring, and ECM connector while observing ECM Data ED01. If the fault is induced, the data value will momentarily jump from a normal reading to -6 degrees or less. Check the TPS test point for a short to ground. Cycle the TPS through its travel and tap on the TPS with a pencil or pocket screwdriver while observing ECM Data ED01 to test for an intermittent TPS. If wiring and connectors check out OK, substitute a known good TPS and retest.