P1603
DTC P1603: Battery Backup Line MalfunctionBattery Backup Circuit:
TECHNICAL DESCRIPTION
- The PCM checks the open circuit of battery backup line
NOTE: When the system detects an open circuit in the battery backup line, it makes 1 failure judgment of other diagnostic trouble codes (DTCs).
DESCRIPTIONS OF MONITOR METHODS
Battery backup line voltage is under specified value
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored)
- Not applicable
Sensor (The sensor is determined to be normal)
- Not applicable
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- Engine starting sequence was completed.
- Battery positive voltage is higher than 10 volts.
Judgement Criteria
- Battery backup line voltage has continued to be 6 volts or lower for 2 seconds
OBD-II DRIVE CYCLE PATTERN
None
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Open or shorted battery backup line, harness damage or connector damage
- PCM failed
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (MUT-III Sub Assembly)
- MB991824: V.C.I
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991923: Power Plant ECU Check Harness
STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Erase the DTC.
4. Start the engine and run it at idle.
5. Read the DTC.
6. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P1603 set?
YES: Go to Step 2.
NO: The inspection is complete.
STEP 2. Measure the backup power supply voltage at PCM connector B-20 by using power plant ECU check harness special tool MB991923.
1. Disconnect the all PCM connectors and connect power plant ECU check harness special tool MB991923 between the separated connectors.
2. Measure the voltage between terminal No. 42 and ground.
- Voltage should be battery positive voltage.
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 5.
NO: Go to Step 3.
STEP 3. Measure the backup power supply voltage at PCM harness side connector B-20.
1. Disconnect the PCM connector B-20 and measure at the harness side.
2. Measure the voltage between terminal No. 42 and ground.
- Voltage should be battery positive voltage.
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 4.
NO: Repair harness wire between battery and PCM connector B-20 (terminal No. 42) because of open circuit or short circuit to ground. Then go to Step 6.
STEP 4. Check harness connector B-20 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Repair harness wire between battery and PCM connector B-20 (terminal No. 42) because of harness damage. Then go to Step 6.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 6.
STEP 5. Check harness connector B-20 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Replace the PCM. Then go to Step 6.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 6.
STEP 6. Using scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P1603 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.