Code No. P1731: 1st Engine Brake Detection


DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Transmission assembly powertrain parts failure
  • Malfunction of the valve assembly (Malfunction of hydraulic valve and hydraulic switch)
  • Malfunction of the A/T-ECU
  • Malfunction of the lock-up and low-reverse brake linear solenoid valve (valve assembly)
  • Malfunction of the low-reverse brake pressure switch (valve assembly)
  • Malfunction of the low clutch pressure switch (valve assembly)
  • Malfunction of the low clutch linear solenoid valve (valve assembly)
  • Malfunction of the low-reverse brake shift solenoid valve (valve assembly)
  • Malfunction of the low clutch, low-reverse brake

DIAGNOSIS PROCEDURE

STEP 1. Check the diagnosis code.
Check that P0841 (Low-clutch pressure switch) and P0988 (Low-reverse brake pressure switch) are set.

Q. Is the diagnosis code set?
Check and repair the relevant diagnosis code system.
Go to Step 2.

STEP 2. Check the diagnosis code.
Check that the diagnosis code other than P1731 (1st engine brake detection) is set.

Q. Is the diagnosis code set?
Check and repair the relevant diagnosis code system.
Go to Step 3.

STEP 3. Check the A/T fluid properties.
Check the status of the A/T fluid properties (smell, colour, fouling).

  • Black: A/T inside damage, seizure
  • Milky: Water intrusion

Q. Is the check result normal?
Go to Step 4.
Remove the A/T from the vehicle, then check and repair the inside.

STEP 4. Check the A/T fluid level.

Q. Is the check result normal?
Go to Step 5.
Adjust the A/T fluid level, and then go to Step 5.

STEP 5. Check the wiring harness, connector, and sensor signal.

  • Check the wiring harness and connectors of the low-clutch pressure switch and low-reverse brake pressure switch.
  • Check the signals of C-42 A/T-ECU connector terminal No. 37 (output shaft speed sensor) and the terminal No. 38 (input shaft speed sensor).
    Refer to .

Q. Is the check result normal?
Go to Step 6.
Repair or replace the failure section.

STEP 6. Hydraulic pressure test
Refer to .

Q. Is the check result normal?
Go to Step 7.
Remove the A/T from the vehicle, then check and repair the inside.

STEP 7. Erase the diagnosis code, and drive the vehicle for a while.
Check that the normal code is displayed.

Q. Is the check result normal?
The procedure is complete.
Return to START.