DTC 21

Code 21 - TPS Open Or Misadjusted:

Wiring Diagram for Code 21 - TPS Open Or Misadjusted:

CODE 21 - TPS OPEN OR MISADJUSTED


Circuit Description:

Code 21 means that the ECM has seen a high TPS voltage for:

^ Over 10 seconds

^ Below a specified RPM (normally curb idle).

^ Below a specified engine load.

Due to the pull-up resistor between Terms. "21" and "2" within the ECM, an open in the TPS circuit will place about 5 volts (high TPS signal) at Term. "2" of the ECM.


Test Description:

1. Checks the circuits from the TPS connector back to the ECM. The circuit should read about 5V because of the pull-up resistor in the ECM. A 10 Meg. ohm resistance meter must be used. A lower resistance voltmeter would read virtually zero at terminal B.


2. Checks to see if the low voltage at the TPS connector is an open in the circuit or a faulty ECM. A normal reading at the ECM is about 5V.

3. This step simulates closed throttle, so dwell should increase if the ECM is good.

4. This step tests the resistance of the TPS switch itself. A normal reading is under 20,000 ohms.