Powertrain Controls - ECM/PCM

Code 22:

CTS Circuit:

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 volt at idle to about 5.0 volts at wide open throttle. The TPS signal is one of the most important inputs used by the PCM for fuel control and for most of the PCM control outputs.

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

1. Code 22 will set if:

^ The ignition key is "ON."
^ TPS signal voltage is less than 0.2 volt for 4.0 seconds.

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

3. With closed throttle, ignition "ON" or at idle, voltage at "BB10" should be 0.33-0.46 volt. If not, check adjustment. If TPS will not adjust to the correct voltage, replace TPS.

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

NOTE: If code 22 is set, the PCM will not allow 4th gear or TCC operation.

DIAGNOSTIC AIDS:

The on-board diagnostics ED01 reads throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward WOT. An open in CKT 416 or 417 will result in a code 22. If CKT 417 is open or grounded when the vehicle engine is started, a high idle may result. ED01 or a scan tool may read the following with CKT 417 open or grounded.

TPS = 0.04 volt or less.
RPM > 1000 in park.
Desired idle = 725 RPM.
IAC Counts > 40.0.
SES light "ON" code 22 set.

If the intermittent is repaired without cycling the key "OFF," ED01 or the scan may read the following.

TPS = 0.42 volt or less.
RPM > 1500 in park.
Desired idle = 725 RPM.
IAC Counts > 55.0.
SES light "OFF."

Check For:

^ Poor Connection or Damaged Harness - Inspect PCM harness connectors for backed out terminal "BB10/BB3," 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, observe ED01 TPS voltage 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 ED01 TPS voltage while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from closed throttle TPS voltage (0.33-0.46 volt) 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.