Inspection Procedure 21: The reverse signal cannot be received. <M/T>


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

COMMENTS ON TROUBLE SYMPTOM
For the M/T vehicles, the ASC-ECU revives the reverse signal from the ETACS-ECU via the CAN communication and makes the operation judgement of the HSA function. If the ASC-ECU cannot receive the reverse signal normally, the CAN bus line, back-up lamp switch, ETACS-ECU, wiring harness, or connectors may be defective.

PROBABLE CAUSES

  • Damaged harness wires and connectors
  • Malfunction of the back-up lamp switch
  • Malfunction of the ETACS-ECU
  • Malfunction of the ASC-ECU

DIAGNOSIS PROCEDURE

STEP 1. 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 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). Then go to Step 8.

STEP 2. M.U.T.-III other system diagnosis code
Check the diagnosis code is set to the ETACS-ECU.

Q. Is the diagnosis code set?
Diagnose the ETACS-ECU (Refer to GROUP 54A - ETACS - Troubleshooting ).
Go to Step 3.

STEP 3. M.U.T.-III data list
Check if ETACS-ECU related signal is set.

  • Turn the ignition switch to the "ON" position.
Item No.
 Item name
 Normal condition
254
 IG voltage
 System voltage
OK: Normal condition is displayed.

Q. Is the check result normal?
Go to Step 4.
Refer to GROUP 54A - ETACS - Input Signal Procedures/Inspection Procedure 2 "The ignition switch (IG1) signal is not received" .

STEP 4. M.U.T.-III data list
Check if ETACS-ECU related signal is set.

  • Turn the ignition switch to the "ON" position.

  • Shift lever is except "R" (Reverse) position.
Item No.
 Item name
 Normal condition
289
 Backup lamp or shift reveres SW
 OFF

  • Turn the ignition switch to the "ON" position.

  • Shift lever is "R" (Reverse) position.
Item No.
 Item name
 Normal condition
289
 Backup lamp or shift reveres SW
 ON
OK: Normal condition is displayed.

Q. Is the check result normal?
Go to step 8.
Go to step 5.

STEP 5. Check the back-up lamp switch.
Check the continuity of the back-up lamp switch (Refer to GROUP 22B - Transmission/Transmission inspection <5M/T>, GROUP 22C - Transmission/Transmission inspection <6M/T>).

Q. Is the check result normal?
Go to Step 6.
Replace the back-up lamp switch.

STEP 6. Check of short to power supply, short to earth, and open circuit in BLP+, BLP1 line between ETACS-ECU connector and back-up lamp switch connector

Q. Is the check result normal?
Go to Step 7.
Repair the connector(s) or wiring harness.

STEP 7. M.U.T.-III data list
Check if ETACS-ECU related signal is set.

  • Turn the ignition switch to the "ON" position.

  • Shift lever is except "R" (Reverse) position.
Item No.
 Item name
 Normal condition
289
 Backup lamp or shift reveres SW
 OFF

  • Turn the ignition switch to the "ON" position.

  • Shift lever is "R" (Reverse) position.
Item No.
 Item name
 Normal condition
289
 Backup lamp or shift reveres SW
 ON
OK: Normal condition is displayed.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS .), and then go to Step 8.

STEP 8. Retest the system.
Check if the HSA works with one occupant (driver) only in the vehicle.

Q. Is the check result normal?
This diagnosis is complete.
Return to Step 1.