DTC 22

Throttle Position Sensor 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 .4 at idle to above 4 volts at Wide Open Throttle (WOT).

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. Code 22 will set if:

^ The ignition key is "ON."
^ TPS signal voltage is less than .2 volt for 4 seconds.

Code 22 Diagnostic Chart:

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Determines if conditions necessary to set Code 22 exist.

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

3. With closed throttle, ignition "ON" or at idle, voltage at "BB10" should be .33 - .46 volt. If not, check adjustment. Adjustments for adjustment procedures. 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 Tech 1 displays throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward WOT.

An open or short to ground 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. The Tech 1 may read the following with CKT 417 open or grounded.

^ TPS .04 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 Tech 1 may read the following:

^ TPS = .42 volt
^ RPM > 1500 in park
^ Desired idle = 725
^ IAC counts > 55
^ "SES" light "OFF"

Check For:
^ Poor Connection or Damaged Harness - Inspect PCM harness connectors for backed out terminal "BB10" and or "BB3", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

^ Intermittent Test - 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 is closed (.33 - .46) to over 4.0 volts (4000 mV) when throttle is held at Wide Open Throttle (WOT) position.