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 CONDITIONS


The M.U.T.-III judges the trouble when the periodically sent data from each ECU can be received normally but the resistance value between CAN_H and CAN_L line is other than from 50 ohms to 70 ohms.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Resistance measurement at C-219 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 C-219 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.

STEP 2. Resistance measurement at C-103 engine-ECU connector.
caution A digital multimeter should be used. For details refer to .


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

(2)Resistance between C-103 engine-ECU connector terminal Nos.117 and 125
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 engine-ECU.