Hard Trouble Code E21: Notes

NOTE: If this code is not displayed during second pass of diagnostic codes, it is an intermittent failure and cannot be diagnosed using this procedure.

ECM supplies 5 volt signal to pin C (circuit No. 474) of TPS and supplies ground path to pin B (circuit No. 476A). TPS signal from pin A (circuit No. 417) is a variable voltage which is dependent on throttle position.

Trouble code indicates that voltage signal from TPS is too high. This can be observed on engine data parameter P.0.1 as reading greater than 77° at part throttle. Possible causes are: Defective TPS, defective wiring, terminals, etc., or ECM unable to process signals properly.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).

If opposite condition (low TPS signal) can be created, then self-diagnostics can be used to detect failure by displaying engine data parameter P.0.1. With opposite condition created, parameter reading of B10 to B7° should be displayed. To create low sensor signal, disconnect TPS connector. If reading is B10 to B7°, circuit No. 476A must be checked for an open. If voltage between TPS test point terminal C (circuit No. 474) and terminal B (circuit No. 476A) is 0 volts, circuit No. 476A is open. If voltage is 5 volts, ECM and wiring are okay. Fault must be improper mating of sensor terminals or faulty TPS sensor.
If reading is B6° or greater, there is a short to voltagein wiring harness or ECM.