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 D-40 resistor connector <vehicles without ASTC> or D-223 ASTC-ECU connector <vehicles with ASTC>.
caution A digital multimeter should be used. For details refer to .
(1)Remove the resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>, and measure at the equipment side.
(2)Resistance at D-40 resistor connector terminal Nos.1 and 2 <vehicles without ASTC>
OK: 120 ± 20 Ω
(3)Resistance at D-223 ASTC-ECU connector terminal Nos.83 and 84 <vehicles with ASTC>
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 resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>.

STEP 2. Resistance measurement at D-04 combination meter connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the combination meter, and measure at the equipment side.
(2)Resistance between D-04 combination meter connector terminal Nos.23 and 24
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 ASTC-ECU connector and the combination meter.
<Not within 120 ± 20 Ω> Replace the combination meter.