FAILURE DIAGNOSIS
1-186
TNV DI Service Manual
Method and Procedure of Failure Diagnosis
3. Check of harness continuity:
• Remove the EGR valve from the harness, and remove E-ECU from the harness.
• Check the harness continuity using a circuit tester.
4. Movement check of the EGR:
• Connect the 2G eco-checker harness between E-ECU and machine’s harness (for details, see [How to
use the 2G eco-checker harness] (P.1-135). And connect the all connectors (EGR valve, E-ECU).
• Connect the diagnosis tool, and log in to the diagnosis tool after key switch turning-on.
• Activate each step motor of the EGR valve by the diagnosis tool “Diagnosis Test: Active control”, and
measure the voltage between step motor coil terminals E31-E45, (E21-E45, E11-E45, E01-E45)
respectively.
Terminal
Continuity
Status
Motor coil (downstream side)
E31(E21/E11/E01)
[Between E-ECU and EGR connector]
Available
OK: normal
Unavailable
NG: harness disconnection
Motor coil (upstream side) E48
[Between E-ECU and EGR connector]
Available
OK: normal
Unavailable
NG: harness disconnection
Between E31 (E21/E11/E01) and
GND/E28/E45/E47
Unavailable
OK: normal
Available
NG: harness short-circuited with GND
Between E31 (E21/E11/E01) and
E43/E48
Unavailable
OK: normal
Available
NG: Harness short-circuited with power
supply
NG
• Check if the harness is damaged, or if the wiring is correct.
• Replace the harness.
OK
Check the movement of the EGR by the diagnosis tool.
→
ON/OFF setting status
Voltage
Status
ON
1.75[V] and below OK: normal
Over 1.75[V]
NG: Harness short-circuited with power supply or E-
ECU fault
OFF
2.5[V] and above
OK: normal
Under 2.5[V]
NG: Harness short-circuited with GND or E-ECU fault
NG
• Check if the harness is damaged, or if the wiring is correct.
• Replace the harness.
OK
Replace the E-ECU.
TNV_DI_SM_A4-Troubleshooting.book 186 ページ 2007年11月15日 木曜日 午後5時27分