Code No.C1522 Engine speed input malfunction


caution
  • If the electric power steering-ECU sets diagnosis code No.C1522, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.




DIAGNOSIS CODE SET CONDITIONS

  • If the system receives an abnormal engine speed signal and the microprocessor determines that the engine speed measurement system is defective.
    • Criteria for judging malfunction
    • When the vehicle maintains the vehicle speed of 15 km/h or above and the engine speed signal stays 0 rpm for 60 seconds

PROBABLE CAUSES

  • Defective wire(s) or connector(s) in the crankshaft angle sensor input circuit of the engine-ECU <M/T> or the engine-A-M/T-ECU <Automated manual transmission>
  • Malfunction of the engine-ECU <M/T> or the engine-A-M/T-ECU <Automated manual transmission>
  • Malfunction of the electric power steering-ECU
  • The vehicle kept running with the engine stopped for 60 seconds or more.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

Go to Step 2.

Repair the CAN bus line (Refer to GROUP 54C - CAN bus line Diagnostic flow ). Then go to Step 2.

STEP 2. M.U.T.-III other system diagnosis code

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check that an engine control system diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is an engine control system diagnosis code set?

Diagnose the engine control system (Refer to GROUP 13A - Troubleshooting - Inspection chart for diagnosis code <134 or 3A9> or GROUP 13B - Troubleshooting - Inspection chart for diagnosis code <135, 4A9> or GROUP 13C - Troubleshooting - Inspection chart for diagnosis code <4G1>). Then go to Step 3 .

Go to Step 3.

STEP 3. M.U.T.-III data list

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Start the engine.
(6)Set M.U.T.-III to data reading mode, and check the data list item.

  • Item 12: Engine speed
OK: The tachometer normal and the reading on the tachometer nearly match the indication on M.U.T.-III.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the engine speed input normal?

Go to Step 4.

Replace the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> (Refer to GROUP 13A - Engine-ECU <134 or 3A9>, GROUP 13B - Engine-ECU, Engine-A-M/T-ECU <135, 4A9>, GROUP 13C - Engine-ECU <4G1>).

STEP 4. Check whether the diagnosis code is reset.

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Start the engine.
(6)Recheck whether diagnosis code C1522 is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.
(8)Disconnect M.U.T.-III.

Q. Is diagnosis code C1522 set?

Replace the electric power steering-ECU (Refer to ).

The malfunction is intermittent. Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .