Code No. U1110: A/C-ECU Time-out

caution

If Diagnosis Code U1110 is output from engine-ECU surely perform CAN busline diagnosis.

caution

Replace ECU after certainly confirming that the communication circuits are normal.

TROUBLE JUDGMENT

Check Conditions

While the cranking switch is in "OFF" position, or when 3 seconds pass after the cranking switch is in "OFF" from "ON".
The battery voltage is 10 V or more.

Judgment Criterion

The signals cannot be received from A/C-ECU through CAN busline.

COMMENT ON TROUBLE SYMPTOM

Current malfunction

The failure is possibly caused by malfunction of the harness and connector in CAN busline between engine-ECU and A/C-ECU or between engine-ECU and A/C-ECU, by malfunction in the power supply system of A/C-ECU, in A/C-ECU itself, in engine-ECU.

Past malfunction

Focus on diagnosing malfunction of the harness and connector in CAN busline between engine-ECU and A/C-ECU as well as malfunction in the power supply system of A/C-ECU. Refer to past trouble (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble

) for the diagnosis procedure.

note

In case of Past trouble, M.U.T.-III CAN bus diagnosis cannot detect the failure even if there is malfunction in CAN bus, so that check CAN busline in the same way as Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

) The diagnosis codes being output to each ECU with CAN communication can narrow down the most suspected area (Refer to GROUP 54C - Troubleshooting - Can Bus Diagnosis Table

PROBABLE CAUSES

Failed of the harness and the connector
Failed A/C-ECU
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

warning

Since the radiator fan rotates during CAN bus line diagnostics, make sure that no one is servicing the engine compartment before diagnosing the CAN bus line. Since the CAN communication stops when diagnosing the CAN bus line, the ETACS-ECU detects the time-out of the engine-ECU, and activates the radiator fan to prevent overheating as fail-safe.

Using M.U.T.-III, perform CAN busline diagnosis.

Q. Is the check result normal?

	Go to Step 2 .

	Correct CAN busline (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnosis Table), and then go to Step 6 .

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

Confirm whether the diagnosis codes are output from A/C-ECU.

Q. Is the diagnosis code output?

	Perform the troubleshooting of A/C-ECU (Refer to GROUP 55B - troubleshooting - Diagnosis Code Chart ).

	Go to Step 3 .

STEP 3. M.U.T.-III other system diagnosis code

Confirm whether Diagnosis Code U1110 A/C-ECU timeout is output from the following ECU having CAN communication with A/C-ECU.

Center display unit
Combination meter
ETASC-ECU

Q. Is the diagnosis code output?

	Go to Step 4 .

	Go to Step 5 .

STEP 4. Reconfirmation of diagnosis codes

Reconfirm whether the diagnosis codes are output from engine-ECU

Erase the diagnosis codes being output.
Ignition switch: "LOCK"(OFF) to ON
Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?

	After replacing the A/C-ECU, go to Step 6 .

	Temporary malfunction in CAN busline between engine-ECU and A/C-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 5. Reconfirmation of diagnosis codes

Reconfirm whether the diagnosis codes are output from engine-ECU

Erase the diagnosis codes being output.
Ignition switch: "LOCK" (OFF) to ON
Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?

	After replacing the engine-ECU, go to Step 6 .

	Temporary malfunction in CAN busline between engine-ECU and A/C-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Reconfirmation of diagnosis codes

Reconfirm whether the diagnosis codes are output from engine-ECU

Erase the diagnosis codes being output.
Ignition switch: "LOCK" (OFF) to ON
Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?

	Go to Step 1 .

	The check is completed.