DTC 21

Code 21 Throttle Position Sensor (Signal Voltage High):

- Wiring Diagram for Code 21 TPS Circuit High.:

CODE 21, TPS CIRCUIT HIGH

CIRCUIT DESCRIPTION
Code 21 means that the ECM has seen a high TPS voltage for:
CHART DESCRIPTIONCODE 22, TPS CIRCUIT LOW

Code 22 means that the ECM has seen the following:
a. Low voltage at ECM terminal "2".
b. For a time in excess of 20 seconds.C a. Over about 10 seconds
b. Below as specified RPM
c. 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.

CHART DESCRIPTION
Step numbers refer to the step numbers on the diagnostic chart.
1. Checks CKTs 417 & 452, from the TPS connector, back to the ECM. Installing a jumper between harness terminals "B" and "C", should pull voltage, at ECM terminal "2", down to well below 2.5 volts.
2. A high voltage of 2.5 volts, or over, at this point, would indicate that CKT 417 is open or, shorted to CKT 416 or, that 452 is open. If both circuits check out OK, the ECM is the cause of the problem.
3. A low voltage reading of below 2.5 volts, here, would indicate that the TPS connections, or the TPS, itself, is faulty.