TROUBLESHOOTING
ENGINE COOLING
14-12
STEP 4. Measure the output circuit voltage at
engine-ECU connector C-121 terminal 18 by
backprobing.
AC505254
16
25
10
24
1
9
24
27
13
26
11
3
12
2829
1415
3031
1718
3332
6
20
5
19 21
35
34
8
23
7
22
JAE
AB
Connector: C-121 <LHD>
Harness side
C-121 (GR)
Engine-ECU
AC505255
16
25
10
24
1
9
24
27
13
26
11
3
12
2829
1415
3031
1718
3332
6
20
5
19 21
35
34
8
23
7
22
JAE
AB
Connector: C-121 <RHD>
Harness side
C-121 (GR)
Engine-ECU
(1) Do not disconnect engine-ECU connector C-121.
(2) Start the engine and allow it to idle.
(3) Turn the A/C switch to the "ON" position.
(4) Measure the voltage between terminal No.18 and
earth by backprobing.
• The voltage should measure 0.7 volt or more
when the cooling fan is operating.
Q: Is the voltage 0.7 volt or more when the cooling fan
is operating?
YES : Go to Step 6.
NO : Go to Step 5.