Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus GX 470. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT FUSE (MAYDAY, GAUGE, AM2, ACC)
1. Remove the MAYDAY and AM2 fuses from the engine room junction block.
2. Remove the ACC and GAUGE fuses from the driver side junction block.
3. Measure the resistance of the fuses.
  Standard resistance:
Below 1 Ω

NG: REPLACE FUSE

OK: Go to next step

INSPECT RELAY (ACC CUT RELAY)

Fig 1: Identifying ACC CUT Relay Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Remove the ACC CUT relay from the engine room relay block.
Measure the resistance of the relay.
Standard resistance

RESISTANCE SPECIFICATION

Tester connection	Specified Condition
3 - 4	Below 1 Ω
3 - 4	10 kΩ or higher (when battery voltage is applied to terminals 1 and 2)

NG: REPLACE RELAY

OK: Go to next step

CHECK WIRE HARNESS (ECU - BATTERY AND BODY GROUND)

Fig 2: Identifying Mayday ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the M15 ECU connector.
Measure the voltage and resistance of the wire harness side connector.
Standard voltage

VOLTAGE SPECIFICATION

Tester Connection	Condition	Specified Condition
M15-1 (+B) - Body ground	Always	10 to 14 V
M15-13 (IG) - Body ground	Ignition switch ON	10 to 14 V
M15-14 (ACC)-Body ground	Ignition switch ACC	10 to 14 V

Standard resistance

RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
M15-12 (E) - Body ground	Below 1 Ω

NOTE: If replacement of the ECU is necessary, replace the mayday battery (backup battery) together with the ECU. After the replacement, register the ECU (See REGISTRATION ).

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE MAYDAY ECU ASSEMBLY (See REMOVAL )