Lexus SC300 / Lexus SC400. Manual

TERMINALS OF ECU

Connectors of the engine & ECT ECU are water–proof and are the
bolt type.
For water proof type connectors, in order to measure the voltage
of ECU terminals and the resistance of connected parts, connect
the inspection sub wire harness between the ECU and vehicle
wire harness, then perform the inspection. The inspection method
of inserting a tester probe from the other side of connector notice-
ably reduces the water–proof ability.
Disconnect the connector by fully loosening the bolt.

PREPARATION

Turn the ignition switch to LOCK position.

Turn up the passenger side floor mat.

Remove the ECU protector.

Disconnect the connector from the ECU.
After completely loosening the bolt, the two parts of the con-
nector can be separated.
NOTICE:

•

Do not pully the wire harness when disconnecting the

connector.

•

When disconnecting the connector, the ECU’s backup

power source is cut off, so the malfunction codes, etc.

recorded in the ECU memory are cancelled.

•

Never insert a tester probe or male terminal used for

inspection purposes into the female terminal of the

vehicle wire harness. Otherwise, the female terminal may

be widened, which can result in faulty connection.

Connect the Check Harness A between ECU and connector
of vehicle wire harness.
SST 09990–01000
HINT: The arrangement of the check connector terminals are
the same as those of the ECU.
See page

TR–31

Disconnect the Check Harness A.

Reconnect the connector to the ECU.
(a) Match the male connector correctly with the female

connector, then press them together.

(b) Tighten the bolt

Make sure the connector is completely connected, by
tightening the bolt until there is a clearance of less than
1 mm (0.04 in.) between bottom of the male connector
and end of the female connector.

Install the ECU protector and floor mat.

TR–30

–

ENGINE TROUBLESHOOTING

Terminals of ECU

Lexus SC300 / Lexus SC400. Manual - part 851