The PCM provides ground
to one side of the coil of the main relay and the other side is connected
to the battery. The PCM monitors battery voltage and the voltage after the
main relay.
Checking the contolling
state of main relay every 10 sec. under detecting condition, if open or
short in the circuit is detected for more than 5 sec., PCM sets
P0685.
Item
|
Detecting
Condition
|
Possible cause
|
DTC
Strategy
|
| •
|
Detects a short to ground, to battery or
open circuit on the main
relay | |
| •
|
Open or short in control
circuit. |
|
EnableConditions
|
| •
|
11V ≤ Ignition Voltage ≤
16V | |
Threshold
value
|
| •
|
Open or Short in
circuit | |
DiagnosisTime
|
| •
|
Contineous
(More than 5sec. Failure for every 10
sec. test) | |
MIL On
Condition
|
|
※ If Main relay has a
fault(ex. Open) while the engine is running, the
DTCs,P0638/P0685/P1295/P2106, can happen at the same time.
<DTC
Name>
| - |
P0638 Throttle Actuator Control
Range/Performance(Bank 1) |
| - |
P0685 PCM/PCM Power Relay Control Circuit
/Open |
| - |
P1295 Throttle Actuator Control System - Power
Management |
| - |
P2106 Throttle Actuator Control System -
Forced Limited Power |
Coil
Resistance
|
70Ω ~
120Ω
|
| 1. |
Check DTC Status
| (1) |
Connect scantool to Data Link
Connector(DLC). |
| (3) |
Select "DTC" button, and then Press "DTC
Status" to check DTC's information from the DTCs
menu. |
| (4) |
Read "DTC Status"
parameter.
|
| (5) |
Is parameter displayed "Present
fault"?
|
|
▶ Go
to "Terminal and connector inspection"
procedure.
|
|
|
▶
Fault is intermittent caused by poor contact in the
sensor's and/or PCM's connector or was repaired and PCM
memory was not cleared. Thoroughly check connectors for
looseness, poor connection, ending, corrosion,
contamination, deterioration, or damage. Repair or
replace as necessary and go to "Verification of Vehicle
Repair"
procedure.
|
| |
| Terminal And Connector
InspeCTION |
| 1. |
Many malfunctions in the electrical system are
caused by poor harness and terminal condition. Faults can also be
caused by interference from other electrical systems, and mechanical
or chemical damage. |
| 2. |
Thoroughly check connectors for looseness,
poor connection, bending, corrosion, contamination, deterioration,
or damage. |
| 3. |
Has a problem been found?
|
|
▶ Repair as
necessary and go to "Verification of Vehicle Repair"
procedure
|
|
|
▶ Go to "
Power Circuit Inspection "
procedure.
|
|
■ Check voltage
| 2. |
Disconnect the main
relay. |
| 4. |
Measure the voltage between power supply
terminals of main relay harness connector and chassis
ground.
|
| 5. |
Is the measured voltage within specification
?
|
|
▶ Go to
"Control Circuit Inspecition" procedure.
|
|
|
▶ Check
fuse between battery and main relay is
disconnected.
▶ Repair or replace
open or short in harness and then go to "Verification of
Vehicle Repair"
procedure.
|
|
| Control Circuit
Inspection |
■ Check short in harness
| 2. |
Disconnect main relay and PCM
connector. |
| 3. |
Measure the resistance between control
terminal of main relay harness connector and chasses
ground.
|
| 4. |
Is the measured resistance within
specification ?
|
|
▶ Go to
"Check open in harness" as follows.
|
|
|
▶ Repair or
replace as necessary and then go to " Verification of Vehicle
Repair"
procedure.
|
|
■ Check open in harness
| 2. |
Disconnect main relay and PCM
connector. |
| 3. |
Measure the resistance between control
terminal of main relay harness connector and main relay control
terminal of PCM harness connector.
Specification
: Approx. below 1Ω
| |
| 4. |
Is the measured resistance within
specifications ?
|
|
▶ Go to
"Component Inspection" procedure.
|
|
|
▶ Repair or
replace as necessary and then, go to "Verification of Vehicle
Repair"
procedure.
|
|
■ Check Main relay
| 2. |
Disconnect the main
relay. |
| 3. |
Measure the resistance between battery power
supply and control terminals of main relay.(Measurement
"A") |
| 4. |
Measure the resistance between battery power
supply and power supply to PCM terminals of main relay.(Measurement
"B")
Specification
: 70 ~ 120Ω
|
Terminal
|
continuity
|
Battery power supply - Power supply to
PCM
|
NO
|
Battery power supply - Main relay
control
|
YES
(Approx. 70Ω ~
120Ω)
|
|
| 5. |
Is the measured reisistance within
specification ?
|
|
▶ ubstitute
with a known - good PCM and check for proper operation. If the
problem is corrected, replace PCM and go to "Verification of
Vehicle Repair" procedure.
|
There is a memory reset function
on scantool that can erase optional parts automatically
detected and memorized by PCM. Before or after testing
PCM on the vehicle, use this function to reuse the PCM
on the others. | |
|
|
▶
Substitute with a known - good Main Relay and check for proper
operation. If the problem is corrected, replace Main Relay and
go to "Verification of Vehicle Repair"
procedure.
|
|
| Verification Of Vehicle
Repair |
After a repair, it is
essential to verify that the fault has been corrected.
| 1. |
Connect scantool and select "DTC"
button. |
| 2. |
Press "DTC Status" button and confirm that
"DTC Readiness Flag" indicates "Completed". If not, drive the
vehicle within conditions noted in the freeze frame data or enable
conditions |
| 3. |
Read "DTC Status"
parameter |
| 4. |
Is parameter displayed "History(Not Present)
fault"?
|
|
▶ System
performing to specification at this time. Clear the
DTC
|
|
|
▶ Go to the
applicable troubleshooting
procedure.
|
|
