With Manual Trans

Code Chart 21:

Code 21 Wiring Diagram:

CIRCUIT DESCRIPTION:

On manual transaxle cars the ECM supplies 4-5 volts to a throttle switch on the throttle body. When engine is idling the ECM sees a low voltage signal at Terminal "A3." At slight throttle the ECM will see a high voltage signal at Terminal "A3." At wide open throttle the signal voltage on Terminal "A15" is low. Code 21 will set if the the following occurs:

^ Engine load indicated high and idle switch signal is low.
^ Engine load indicated low and WOT switch signal is low.
^ One of the above conditions present for 0.3 seconds or more.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. The ECM supplies 5.0 volts to the throttle switch. Poor connection or a ground circuit will indicate a low signal.

2. This will check circuit for short to ground or misadjusted throttle switch.

3. See ADJUSTMENT PROCEDURES for throttle switch adjustment.

DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect ECM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness. For additional information, Testing and Inspection