Powertrain Controls - ECM/PCM

Code 22 Chart:

TPS Circuit Wiring Diagram:

CIRCUIT DESCRIPTION

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.5 at idle to about 5 volts at Wide Open Throttle (WOT). The TPS signal is one of the most important inputs used by the Electronic Control Module (ECM) for fuel control and for most of the ECM control outputs.

TEST DESCRIPTION Numbers below refer to circled numbers on the diagnostic chart.

1. Code 22 will set if:

^ The engine running.

^ TPS signal voltage is less than about 0.2 volt for 3 seconds.

^ The TPS has an auto zeroing feature. If the reading is within the range of 0.3 to 1.0 volts, the ECM will use that value as closed throttle. If the voltage reading is out of voltage range at closed throttle, make sure the cruise and throttle cables are not being held open. If ok continue on with diagnosis.


2. Simulates Code 21: (high voltage) If the ECM recognizes the high signal voltage the ECM and wiring are OK.

3. This simulates a high signal voltage to check for an open in CKT 417.

DIAGNOSTIC AIDS

A "Scan" tool reads throttle position in volts. Should read between 0.36 and 0.96V with throttle closed and ignition "ON" or at idle. Voltage should increase at a steady rate as throttle is moved toward WOT. An open or short to ground in CKTs 416 or 417 will result in a Code 22. - Intermittent Malfunctions