Powertrain Controls - ECM/PCM

Code 22 Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION:

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from about 0.4 at idle to about 5.0 volts at wide open throttle. The TPS signal is one of the most important inputs used by the ECM for fuel control and for most of the ECM control outputs.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.

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

1. Code 22 will set if the ignition key is "ON" and the TPS signal voltage is less than 0.1 volt for 4 seconds.

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

3. With closed throttle, ignition "ON" or at idle, voltage at "YD13" should be 0.33 - 0.46 volt. If not, check adjustment.

4. Simulates a high signal voltage. Checks CKT 417 for an open.

DIAGNOSTIC AIDS:

^ "Scan" tool reads throttle position in volts. 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.

^ If circuit 417 is open or grounded when the vehicle engine is started a high idle may result a scan tool may read the following.

^ TPS = 0.4 volt or less.
^ RPM > 1000 in park.
^ Desired idle = 725.
^ IAC counts > 40
^ SES light "ON." Code 22 set.

^ If the intermittent is repaired without cycling the key "OFF" the Scan may read the following.

^ TPS = 0.42 volts or less.
^ RPM > 1500 in park.
^ Desired idle = 725.
^ IAC counts > 55
^ SES light "OFF".

Check for:

^ Poor Connection or Damaged Harness. inspect ECM harness connectors for backed out terminal "YD13," improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

^ Intermittent Test. If connections and harness check OK, monitor TPS voltage display while moving related connectors and wiring harness. If the failure is induced, the display will change. This may help to isolate the location of the malfunction.

^ TPS Scaling. Observe TPS voltage display while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from closed throttle TPS voltage when throttle was closed, to over 4.0 volts (4000 mV) when throttle is held at wide open throttle position. Typically, accelerator pedal travel only yields 4.1 or 4.2 volts maximum, but full throttle rotation at the throttle body should be about 5.1 volts.