Code No. C1912: Tyre air pressure low, Tyre1
Code No. C1922: Tyre air pressure low, Tyre2
Code No. C1932: Tyre air pressure low, Tyre3
Code No. C1942: Tyre air pressure low, Tyre4


caution
  • If diagnosis code No. C1912, C1922, C1932 or C1942 is set, diagnose the CAN bus lines.
  • When replacing the ECU, always check that the communication circuit is normal.

DIAGNOSIS FUNCTION
When the tyre pressure included in the signal from the TPMS transmitter is less than the specified value, ETACS-ECU <Vehicles without KOS> or KOS-ECU sets this code.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Drop of tyre pressure
  • Loose TPMS transmitter mounting nut
  • Flat tyre
  • TPMS transmitter malfunction
  • ETACS-ECU <Vehicles without KOS> or KOS-ECU malfunction
  • CAN-bus line malfunction

DIAGNOSIS PROCEDURE

STEP 1. Tyre check
Check that there is no abnormality for the items below.

  • Flat tyre
  • Cracked tyre
  • Air leak from valve
  • Loose TPMS transmitter mounting nut (Refer to ).

Q. Is the check result normal?
Go to Step 2.
Replace it. Then go to Step 2.

STEP 2. Check whether the diagnosis code is set again.
(1)Turn the ignition switch (engine starting switch) from the "LOCK" (OFF) to "ON" position.
(2)Adjust the pressure to the recommended tyre pressure.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Go to Step 3.
The procedure is complete.

STEP 3. Check whether the diagnosis code is set again.
(1)Drive the vehicle for 5 minutes.
note Even within 5 minutes, if the TPMS warning lamp goes out, finish the driving and perform the operation (2).
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Go to Step 4.
The procedure is complete.

STEP 4. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 6.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting). On completion, go to Step 5.

STEP 5. Check whether the diagnosis code is set again.
(1)Turn the ignition switch (engine starting switch) from the "LOCK" (OFF) to "ON" position.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Go to Step 6.
The procedure is complete.

STEP 6. Tyre pressure check by M.U.T.-III
(1)Perform the transmitter check using the M.U.T.-III (Refer to ), and check the tyre pressure values of all the wheels.
(2)Check the tyre pressure of all the wheels using the tyre pressure gauge.
(3)Compare the measured value (1) with (2).
OK: 20 kPa or less
note Do not replace the TPMS transmitter which cannot be checked.

Q. Is the check result normal?
Replace the KOS-ECU (Refer to GROUP 42B - KOS-ECU ) <Vehicles without KOS> or ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ) and register the ID codes. Then go to Step 9.
Go to Step 7.

STEP 7. Tyre pressure check by M.U.T.-III
(1)Perform the transmitter check using the M.U.T.-III (Refer to ), and check the tyre pressure values of all the wheels.
(2)Check the tyre pressure of all the wheels using the tyre pressure gauge.
(3)Compare the measured value (1) with (2).
OK: 20 kPa or less

Q. Is the check result normal?
Replace the KOS-ECU (Refer to GROUP 42B - KOS-ECU ) <Vehicles without KOS> or ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ) and register the ID codes. Then go to Step 9.
Replace the TPMS transmitter and register the ID codes (Refer to ). Then go to Step 8.

STEP 8. Check whether the diagnosis code is set again.
(1)Turn the ignition switch (engine starting switch) from the "LOCK" (OFF) to "ON" position.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the KOS-ECU (Refer to GROUP 42B - KOS-ECU ) <Vehicles without KOS> or ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ) and register the ID codes. Then go to Step 9.
The procedure is complete.

STEP 9. Check whether the diagnosis code is set again.
(1)Turn the ignition switch (engine starting switch) from the "LOCK" (OFF) to "ON" position.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Start over at Step 1.
The procedure is complete.