1) Disconnect the connector from TCM.
2) Turn the ignition switch to ON.
3) Measure the voltage between TCM connector and chassis ground.
Connector & terminal
(B54) No. 25 (+) — Chassis ground (−): (B54) No. 26 (+) — Chassis ground (−): (B54) No. 27 (+) — Chassis ground (−):
Is the voltage 10 — 13 V?