Diagnosis Item 4: Diagnose the terminator resistors

caution

When servicing a CAN bus line, earth yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken.

FUNCTION

The resistance in the communication errors condition cannot be measured by the CAN bus diagnostics, therefore, judge the terminator resistor only when receiving the each ECU periodically sent data normally.

TROUBLE JUDGEMENT

When all of the following conditions are met, the M.U.T.-III determines that the abnormality is present between terminator resistors.

The M.U.T.-III can receive the periodic transmission data from all ECUs.
The voltage between CAN bus lines (CAN_L and CAN_H lines) is 1.0 V or more, 4.0 V or less.
The resistance at CAN bus line (CAN_L and CAN_H lines) is between 50 Ω and 70 Ω.

PROBABLE CAUSES

Damaged harness wires and connectors
Malfunction of the ETACS-ECU
Malfunction of the EV-ECU

DIAGNOSIS PROCEDURE

STEP 1. Resistance measurement at B-317 ETACS-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1)Remove the ETACS-ECU, and measure at the equipment side.

(2)Resistance at B-317 ETACS-ECU connector terminal Nos.56 and 65
OK: 120 ± 20 Ω

Q. Is the check result normal?

<Within 120 ± 20 Ω> Go to Step 2.

<Not within 120 ± 20 Ω> Replace the ETACS-ECU and register the ID codes (Refer to GROUP 54A, Immobilizer system - On-vehicles service

STEP 2. Resistance measurement at C-108 EV-ECU connector.

caution

A digital multimeter should be used. For details refer to

(1)Remove the EV-ECU, and measure at the equipment side.

(2)Resistance between C-108 EV-ECU connector terminal Nos.54 and 55
OK: 120 ± 20 Ω

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Q. Is the check result normal?

<Within 120 ± 20 Ω> Repair the wiring harness between the ETACS-ECU connector and the engine-ECU connector.

<Not within 120 ± 20 Ω> Replace the EV-ECU and register the ID codes (Refer to GROUP 54A, Immobilizer system - On-vehicles service

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