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TECHNICAL DESCRIPTION
• The fan controller has variable control of the cool-
ing fan motor speed using signals transmitted
from the engine-ECU.
TROUBLESHOOTING HINTS
• Malfunction of fan control relay
• Malfunction of fan controller
• Malfunction of engine-ECU
DIAGNOSIS
STEP 1. Check the fan control relay.
Refer to P.14-17.
Q: Is the fan control relay in good condition?
Go to Step 2.
YES :
Replace the part, then go to Step 8.
NO :
STEP 2. Check the harness wire between fan
control relay connector A-09X terminal 2 and fan
controller connector A-17 terminal 3.
Connector: A-09X
Connector: A-17
Fan controller
A-17 (GR)
Component side
Q: Are the harness wire between fan control relay
connector A-09X and fan controller connector A-17
damaged?
Repair or replace the part, then go to Step
YES :
6.
Go to Step 3.
NO :
ENGINE COOLING
TROUBLESHOOTING
STEP 3. Measure the output circuit voltage at
engine-ECU connector C-121 terminal 18 by
backprobing.
A-09X
3
4
2
1
Relay box
side
AC310900AB
(1) Do not disconnect engine-ECU connector C-121.
(2) Start the engine and allow it to idle.
(3) Measure the voltage between terminal No.18 and
AC210859
AD
Q: Is the voltage less than 0.3 volt when the cooling
fan is not operating?
YES :
NO :
Connector: C-121 <LHD>
1
2
3
4
JAE
9
10
11
12
13
1415
16
24
25
26
27
2829
Harness side
Connector: C-121 <RHD>
Engine-ECU
C-121 (GR)
1
2
3
4
JAE
9
10
11
12
13
1415
16
24
25
26
27
2829
Harness side
earth by backprobing.
• The voltage should measure less than 0.3 volt
when the cooling fan is not operating.
Go to Step 6.
Go to Step 4.
14-11
Engine-ECU
C-121 (GR)
5
6
7
8
1718
19
20
21
22
23
3031
32
33
34
35
AC505254
AB
5
6
7
8
1718
19
20
21
22
23
3031
32
33
34
35
AC505255
AB
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