ECU Power Source Circuit: Procedure

1. Turn the engine switch off.
2. Connect the Techstream to the DLC3.
3. Turn the engine switch on (IG) and the Techstream on.
4. Enter the following menus: Chassis / Air suspension / Data List.
5. Check the values by referring to the table below.
   AIR SUSPENSION
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   IG Power source Voltage	ECU power supply voltage/ min.: 0 V max.: 25.5 V	Engine switch on (IG): 11 to 14 V	-

   OK

   11 to 14 V

   RESULT
   
   

   Result	Proceed to
   NG	A
   OK	B

B → See step   8 

A: Go to next step 

1. Remove the AIR SUS fuse from the passenger side junction block.
2. Measure the resistance of the fuse.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   AIR SUS fuse	Always	Below 1 Ω

NG → See step   7 

OK: Go to next step 

1. Disconnect the L88 ECU connector.
   Fig 1: Identifying L88 ECU And PA Passenger Side Junction Block Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   L88-1 (B) - L88-4 (GND)	Engine switch on (IG)	11 to 14 V

   RESULT
   
   

   Result	Proceed to
   NG	A
   OK	B

B → See step   9 

A: Go to next step 

1. Disconnect the L88 ECU connector.
2. Disconnect the PA passenger side junction block connector.
3. Measure the resistance according to the value in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   L88-1 (B) - PA-44	Always	Below 1 Ω
   L88-4 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the PL junction block connector.
2. Measure the voltage according to the value(s) in the table below.
   Fig 2: Identifying PL Junction Block Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard voltage

   Tester Connection	Condition	Specified Condition
   PL-1 - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the PA junction block connector.
2. Measure the voltage and resistance according to the value(s) in the table below.
   Fig 3: Identifying PA Junction Block Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   PA-15 - Body ground	Engine switch on (IG)	11 to 14 V

   Standard resistance

   Tester Connection	Condition	Specified Condition
   PA-39 - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the L88 ECU connector.
2. Connect the PA passenger side junction block connector.
   Fig 4: Identifying L88 ECU And PA Passenger Side Junction Block Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance according to the value in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   L88-1 (B) - Body ground	Always	10 kΩ or higher

   HINT: 

   If the fuse is blown, replace the fuse.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE PASSENGER SIDE JUNCTION BLOCK