DTC C1242/42: IG2 Power Source Circuit: Procedure

1. Remove the IGN fuse from the engine room No. 2 relay block.
2. Remove the IG2 MAIN fuse from the engine room No. 1 relay block.
3. Remove the IG2 fuse from the passenger side junction block.
4. Measure the resistance of the fuses.

   Standard resistance

   Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Check the battery voltage.

   Standard voltage

   11 to 14 V

   RESULT
   
   

   Result	Proceed to
   Battery voltage is OK (when using Techstream)	A
   Battery voltage is OK (when not using Techstream)	B
   Battery voltage is abnormal	C

C → RECHARGE OR REPLACE BATTERY 

B → See step   4 

A: Go to next step 

1. Check the Data List for proper functioning of the IG voltage.
   ABS/VSC/TRAC
   
   

   Tester Display	Measurement Item / Range	Normal Condition	Diagnostic Note
   ECU IG Power Voltage	ECU power supply voltage / LOW/NORMAL/HIGH	LOW: Below 10 V NORMAL: 10 to 14 V HIGH: 14 V or more	-

   RESULT
   
   

   Result	Proceed to
   Display is not NORMAL	A
   Display is NORMAL	B

B → REPLACE SKID CONTROL ECU 

A: Go to next step 

Fig 1: Inspecting Circuit Opening Relay

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the IG2 relay from the engine room No. 1 relay block.
2. Measure the resistance of the relay.

   Standard resistance

   Tester Connection	Specified Condition
   3 - 5	10 kΩ or higher
   3 - 5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

NG → REPLACE IGNITION RELAY NO. 2 

OK: Go to next step 

Fig 2: Checking Wire Harness (Skid Control ECU - Battery And Body Ground)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the S5, S6 and S8 ECU connectors.
2. Turn the ignition switch ON.
3. Measure the voltage of the wire harness side connectors.

   Standard voltage

   Tester Connection	Specified Condition
   S6-6 (IG2) - S5-16 (GND4)	10 to 14 V
   S6-6 (IG2) - S5-22 (GND3)	10 to 14 V
   S6-6 (IG2) - S8-6 (GND2)	10 to 14 V
   S6-6 (IG2) - S8-31 (GND1)	10 to 14 V
   S6-6 (IG2) - Body ground	10 to 14 V

4. Measure the resistance of the wire harness side connectors.

   Standard resistance

   Tester Connection	Specified Condition
   S5-16 (GND4) - Body ground	Below 1 Ω
   S5-22 (GND3) - Body ground	Below 1 Ω
   S8-6 (GND2) - Body ground	Below 1 Ω
   S8-31 (GND1) - Body ground	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS AND CONNECTOR 

OK → REPLACE SKID CONTROL ECU