Signal Circuit Inspection

Ignition "ON" & Engine "ON".
Put and release the brake pedal several times.
Measure voltage, waveform between terminal "12" of the HECU harness connector and chassis ground.
Specification :

0.2 ± 0.1V ~ 4.8 ± 0.1V

0.2 ± 0.1V (in case of no braking)

Fig 1: Measuring Voltage, Waveform Between Terminal "12" Of HECU Connector Ground
Courtesy of KIA MOTORS AMERICA, INC.
Is the measured voltage, waveform within specifications (isn't there excessive variation in waveform)?
YES
- Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.
NO
- Check for open or short in pressure sensor harness between terminal "1" of the pressure sensor harness connector and terminal "12" of the HECU harness connector. Repair as necessary and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.
- If OK, Go to "COMPONENT INSPECTION " procedure.