GENERAL -How to Use Troubleshooting/Inspection Service Points00-10
HOW TO USE THE INSPECTION PROCEDURES
The causes of a high frequency of problems occurring in electronic circuitry are generally the connectors,
components, the ECU and the harnesses between connectors, in that order. These inspection procedures
follow this order, and they first try to discover a problem with a connector or a defective component.
D
Indicator does not turn on or off even if control
mode switch is pressed.
D
Indicator switch should not be illuminated is
illuminated.Probable cause
OK
OK
OK
Measure at switch connector A-44
DDisconnect the connector, and measure at the harness
side.
DVoltage between terminal 6 - earth and terminal 8 -
earth
OK:Approx. 5V
OK
NG
Check the following connector.A-44
Repair
OK
Check trouble symptom.
Replace the ECS-ECU.
In the above cases, the ECS switch circuit is defective or the indicator
circuit is defective.
CHECKING PROCEDURE 4
2. Indicates inspection carried out using the
MUT-
II.
Indicates the operation and inspection proce-
dures.
Indicates the OK judgement conditions.
3. Detailed inspection procedures (methods)
such as component inspection andcircuit
inspection are listed on a separate page, and
are given here for reference.
5. Inspect the contact condition at each connectorterminal.
(Refer to Connector Inspection Service Points.)
The connector position can be located in the wiring diagram in the
electrical wiring manual bymeans ofthis symbol.
Caution
After carrying out connector inspection, always be sure to
reconnect the connector as it was before.
6. Confirm that there are trouble symptoms. If trouble symptomshave
disappeared, the connector may have been inserted incorrectly and the
trouble symptom mayhave disappeared during inspection.
If it seemsthat trouble symptoms still remain, proceed to the nextpage of
instructions.
7. If trouble symptoms still remain up to this stage, there is a possibility that there is an
open orshort circuit in the harness between the connectors, socheck the harness.
Alternatively, the cause may be a defectiveECU, so try replacing the ECU andcheck
if the trouble symptom disappears.
NGECU switch component inspection (Refer to P.33-44.)
NG
1. Comments on the diagnosis code ortrouble
symptom above.
MUT-II
Data list
17 Control mode selectionswitch
OK:Voltage changes between approx. 0V
®approx.
2.5V
®approx. 5V when the switch is operated.
4. Indicates voltage and resistance to be measured at a particular
connector.
(Refer to Connector Measurement Service Points.)
The connector position can be located in the wiring diagram in the
electrical wiring manual bymeans ofthis symbol.
Indicates operation and inspection procedures, inspection terminals
and inspection conditions.
Indicates the OK judgement conditions.
HARNESS INSPECTION
Check for an open or short circuit in the harness between the terminals which were defective according
to the connector measurements. Carry out this inspection while referring to the electrical wiring manual.
Here, “Check harness between power supply and terminal xx” also includes checking for blown fuses.
For inspection service points when there is a blown fuse, refer to “Inspection Service Points for a Blown
Fuse.”
MEASURES TO TAKE AFTER REPLACING THE ECU
If the trouble symptoms have not disappeared even after replacing the ECU, repeat the inspection procedure
from the beginning.
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DIESEL FUEL <4D5-stepIII>-Troubleshooting13E-36
INSPECTION PROCEDURE 19
A/C condenser fan operating problem
Probable cause
The power transistor inside the engine-ECU turns on and off to control the A/C
condenser fan motor relay.DMalfunction of A/C condenser fan motor relay
DMalfunction of A/C condenser fan motor
DMalfunction of thermostat
DOpen circuit or short-circuit in circuit, or poor
connector contact
DMalfunction of engine-ECU
Check the following connector:D-110
OK
Measure at engine-ECU connector D-110.
DDisconnect the connector and measure at the harness
side.
DCheck the A/C condenser fan condition.
(Ignition switch: ON)
OK:Fan stopped
DVoltage between 7 and the earth
(Ignition switch: ON)
OK:System voltage
DShort out 7 and the earth
(Ignition switch: ON)
OK:A/C condenser fan turnsNGA/C condenser fan motor circuit check
(Refer to the wiring harness configuration diagram.)
OK
MUT-IIData list
02 Engine coolant temperature sensor
OK:When engine is idling after having warmed up, the en-
gine coolant temperature and the MUT-IIdisplay temper-
ature are identicalNGEngine coolant temperature sensor check
(Refer to Code 15 on P.13E-59.)
Check the trouble symptoms.OK
Replace the engine-ECU.NG
Repair
Thermostat checkNG
NGReplace
OK
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