DTC 22

Throttle Position Sensor (TPS) Circuit 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 0.5 at idle to about 5 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.

Code 22 will set if:

^ Engine is running and TPS voltage is less than 0.25 volts for 10 seconds.

TEST DESCRIPTION

Code 22 Diagnostic Chart:

Numbers below refer to circled numbers on diagnostic chart.
1. With closed throttle, ignition "ON," or at idle, voltage at PCM terminal C15 should be 0.29 - 0.98 volt.
2. Simulates conditions for a Code 21. If the PCM recognizes the high circuit voltage, them PCM and wiring are OK.
3. TPS check. The PCM has an automatic "zero" feature programmed into it for the throttle position sensor. If the signal voltage is between 0.29 and 0.98 volts when the ignition is turned "ON", the PCM will assume that value as the reference value for closed throttle. If the voltage is outside of the "auto-zero" range on an existing or replacement TPS, check that throttle is closing completely and that cruise control and throttle cables are not sticking, binding or incorrectly adjusting.
4. This simulates a high signal voltage to check for an open in circuit 417
5. The TPS and MAP sensors share a common buffered 5 volt reference source inside the PCM. If either of these circuits is shorted to ground, a code 22 will set. To determine which sensor is causing the code, clear codes, disconnect the MAP sensor and see if Code 22 recurs. If code 22 does not recur, problem is in reference voltage circuit to MAP sensor.


DIAGNOSTIC AIDS:

^ Scan tool reads throttle position in volts. With closed throttle, ignition "ON" or at idle, voltage should be approx. 0.5 volt.
^ Also some "Scan" tools will read throttle angle as a percentage. 0% = closed throttle, 100% = WOT. An open in CKT 808 will result in a Codes 15 and 21 and will turn the temp. warning light "ON". An open or short to ground in circuits 416 or 417 will result in a Code 22.

Check For:

^ Poor Connection or Damaged Harness Inspect PCM harness connectors for backed out terminals 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 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 appriox. 0.5 volt, when throttle was closed, to over 4.0 volts when throttle is wide open. Typically, accelerator pedal fully depressed should yield approx. 4.1 - 4.2 volts from the sensor. If operating throttle by hand, approx. 4.8 volts may be obtained. If voltage is greater than 4.8 volts, replace the TPS.