Inspection procedure 2: The Hill Decent Control (HDC) Switch Signal is not Received.

caution

Whenever the ECU is replaced, ensure that the input signal circuit is normal.

COMMENTS ON TROUBLE SYMPTOM

If there is an error to the hill decent control (HDC) switch input signal, the hill decent control (HDC) switch signal is no longer output to the communication line.

PROBABLE CAUSES

Malfunction of hill decent control (HDC) switch
Malfunction of the gateway-ECU
Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Check the input signals from the hill decent control (HDC) switch.

Operate the hill decent control (HDC) switch.

Item No.	Item name	Normal condition
2	HDC SW	OFF to ON (only when switch is operated)

OK: Normal condition is displayed.

Q. Is the check result normal?

Go to Step 3.

Go to Step 2.

STEP 2. Check the wiring harness between hill decent control (HDC) switch connector and the gateway-ECU connector.

Check of short to power supply, short to earth, and open circuit between gateway-ECU connector and hill decent control (HDC) switch

Q. Is the check result normal?

Go to Step 3.

Repair the connector(s) or wiring harness.

STEP 3. Check the hill decent control switch

Refer to GROUP 35C - Hill Decent Control (HDC) Switch, Inspection

Q. Is the check result normal?

Go to Step 4.

Replace the hill decent control (HDC) switch.

STEP 4. M.U.T.-III data list

Operate the hill decent control (HDC) switch.

Item No.	Item name	Normal condition
2	HDC SW	OFF to ON (only when switch is operated)

OK: Normal condition is displayed.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction

Replace the gateway-ECU (Refer to