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 judgement 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 is lower than 6 volts 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
- MB991911: Main Harness B
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 C-113 by backprobing.
1. Do not disconnect the PCM connector C-113.
2. Measure the voltage between terminal No. 58 and ground by backprobing.
- 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 C-113.
1. Disconnect the PCM connector C-113 and measure at the harness side.
2. Measure the voltage between terminal No. 58 and ground.
- Voltage should be battery positive voltage.
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 4.
NO: Check connector A-13 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If the intermediate connector is in good condition, repair harness wire between battery and PCM connector C-113 (terminal No. 58) because of open circuit or short circuit to ground. Then go to Step 6.
STEP 4. Check harness connector C-113 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Check harness connector A-13 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If the intermediate connector is in good condition, repair harness wire between battery and PCM connector C-113 (terminal No. 58) 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 C-113 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.