1) Disconnect the connectors from ECM.
2) Measure the resistance of harness between ECM and chassis ground.
Connector & terminal
Euro 4 model
(B134) No. 3 — Chassis ground: (B134) No. 4 — Chassis ground: (B134) No. 5 — Chassis ground: (B134) No. 6 — Chassis ground: (B134) No. 7 — Chassis ground: (B135) No. 3 — Chassis ground: (B135) No. 4 — Chassis ground: (B137) No. 1 — Chassis ground: (B137) No. 6 — Chassis ground: (B137) No. 7 — Chassis ground:
Euro 5 model
(B134) No. 3 — Chassis ground: (B134) No. 4 — Chassis ground: (B135) No. 3 — Chassis ground: (B135) No. 4 — Chassis ground: (B135) No. 5 — Chassis ground: (B135) No. 7 — Chassis ground: (B136) No. 6 — Chassis ground: (B137) No. 6 — Chassis ground: (B137) No. 7 — Chassis ground:
Is the resistance less than 5 Ω?
Repair the harness and connector.
NOTE:
In this case, repair the following item:
• Open circuit in harness between ECM and engine ground terminal
• Poor contact of coupling connector