3.
Monitor "Main Relay" parameter on scantool.
One terminal of main relay is connected to battery and the other terminal which is ground point is conneted to PCM. PCM monitors the voltages flowing into main relay and going through it.
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 Main Relay output Fault information provided by an output driver chip. | ● Poor Connection ● Open or short in control circuit. ● Main Relay ● PCM |
EnableConditions | ● Engine Running ● 11V ≤ Ignition Voltage ≤ 16V ● Enable Time delay ≥ 0.5sec. | |
Threshold value | ● Open or Short | |
DiagnosisTime | ● Contineous (More than 5sec. Failure for every 10 sec. test) | |
MIL On Condition | ● DTC only (NO MIL ON) |
Coil Resistance |
70Ω ~ 120Ω |
Connect scantool to DLC(Data Link Connector)
Warm up the engine to normal operating temperature.
Monitor "Main Relay" parameter on scantool.
Is the "Main Relay" parameter displayed correctly ?
▶ Fault is intermittent caused by poor contact in Sensor’s and/or PCM’s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to "Terminal and Connector Inspection" procedure.
Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to " Power Circuit Inspection " procedure.
IG "OFF"
Disconnect Main Relay
IG "ON" ＆ ENG "OFF".
Measure voltage between harness terminal 2 of Main Relay and chassis ground.
Measure voltage between harness terminal 5 of Main Relay and chassis ground.
Specification : B+
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.
Check short in coil control
IG "OFF".
Disconnect Main Relay and PCM connector.
Measure resistance between harness terminal 4 and chassis ground.
Measure resistance between harness terminal 4 and 5 of Main Relay.
Specification : Infinite
Is the measured resistance within specification ?
▶ Go to "Check open in coil control" as follows.
▶ Repair or replace as necessary and then go to " Verification of Vehicle Repair" procedure.
Check open in coil control
IG "OFF".
Disconnect Main Relay and PCM connector.
Measure resistance between harness terminal 4 of Main Relay and harness terminal 43 of PCM harness connector.
Specification : Approx. below 1Ω
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
IG "OFF"
Disconnect Main Relay
Measure resistance between terminal 5 and 3 of Main Relay
Measure resistance between terminal 4 and 2 of Main Relay.
Terminal | continuity |
3 ~ 5 | NO |
2 ~ 4 | YES (Approx. 70Ω ~ 120Ω) |
Is the measured reisistance within specification ?
▶ Substitute 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.
▶ 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.
After a repair, it is essential to verify that the fault has been corrected.
Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
Using a Scantool, Clear the DTCs
Operate the vehicle within conditions noted in the freeze frame data or enable conditions
Monitor that all rediness test have been verified as " Complete "
Are any DTCs present ?
▶ Go to the applicable troubleshoooting procedure.
▶ System is performing to specification at this time.
