DTC 21

DIAGNOSTIC CHART





WIRING DIAGRAM

INSPECTION PROCEDURE

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

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. DTC 21 will set if:
- TP Sensor signal voltage is greater than 2.5 volts.
- All conditions met for 8 seconds.
- Manifold Absolute Pressure (MAP) less than 52 kPa.
2. With the TP sensor disconnected, the TP sensor voltage should go low if the ECM and wiring are OK.
3. Probing CKT D2 with a test light to 12 volts checks the sensor ground CKT. A faulty sensor ground will cause a DTC 21.

Diagnostic Aids:
A "Scan" tool reads throttle position in volts. Should read less than 1.25 volts with throttle closed and ignition "ON" or at idle. Voltage should increase at a steady rate as throttle is moved toward WOT.
An open in CKT D2 will result in a DTC 21.
Refer to "Intermittents" in "Symptoms" or AUTOMATIC TRANSMISSION.