P1731

DTC P1731: 1st Engine Brake Detection

DESCRIPTIONS OF MONITOR METHODS

- With the mode other than SPORT MODE and with the accelerator angle is smaller than 6/8, the correlation between the lock-up and low-reverse brake linear solenoid valve control current and the low-reverse brake pressure switch ON/OFF is abnormal.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)

- Transaxle assembly powertrain parts failure

- Malfunction of the valve assembly (Malfunction of hydraulic valve and hydraulic switch)

- Malfunction of the TCM

- 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

STEP 1. Check the DTC.

Check that P0988 (Low-reverse brake pressure switch) is set.

Q. Is the DTC set?

YES Check and repair the relevant DTC system.
NO Go to Step 2.
STEP 2. Check the DTC.

Check that the DTC other than P1731 (1st engine brake detection) is set.

Q. Is the DTC set?

YES Check and repair the relevant DTC system.
NO Go to Step 3.
STEP 3. Check the transmission fluid properties.

Check the status of the transmission fluid properties (smell, color, fouling).

- Black: A/T inside damage, seizure

- Milky: Water intrusion

Q. Is the check result normal?

YES Go to Step 4.
NO Remove the A/T from the vehicle, then check and repair the inside.
STEP 4. Check the transmission fluid level.

Q. Is the check result normal?

YES Go to Step 5.
NO Adjust the transmission 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-37 TCM connector terminal No. 37 (output shaft speed sensor) and the terminal No. 38 (input shaft speed sensor).
Refer to Automatic Transmission.

Q. Is the check result normal?

YES Go to Step 6.
NO Repair or replace the failure section.
STEP 6. Hydraulic pressure test

Refer to Hydraulic Pressure Test.

Q. Is the check result normal?

YES Go to Step 7.
NO Remove the A/T from the vehicle, then check and repair the inside.
STEP 7. Erase the DTC code, and drive the vehicle for a while.

Check that the normal code is displayed.

Q. Is the check result normal?

YES The procedure is complete.
NO Return to START.