1) Start the engine.
2) Measure the voltage between ECM connector and chassis ground.
Connector & terminal
Non-turbo model
(B135) No. 25 (+) — Chassis ground (−):
Turbo model
(B136) No. 22 (+) — Chassis ground (−):
Is the voltage 0 ←→ 14 V or more?
Inspect the ECM.