P1603

Connectors:

TECHNICAL DESCRIPTION
- The ECM or PCM is checks the open circuit of battery backup line.

DTC SET CONDITIONS

Check Conditions
- Ignition switch: ON

Judgement Criteria
- The backup memory is lost.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Open or shorted battery backup line, or loose connector.
- ECM failed.
- PCM failed.

DIAGNOSIS

Required Special Tools
MB991502: Scan Tool (MUT-II)

STEP 1. Check if the battery terminal is disconnected.

Q: Is the battery terminal disconnected before reading the DTC?

YES: Turn the ignition switch to the "LOCK" (OFF) position, and then in 10 seconds turn the ignition switch to the "ON" position. Then go to Step 2.

NO: Go to Step 3.

STEP 2. Using scan tool MB991502, read the diagnostic trouble code (DTC).

CAUTION: To prevent damage to scan tool MB991502, always turn the Ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 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 the DTC P1603 is output?

YES: Go to Step 3.

NO: The inspection is complete.

STEP 3. Check the backup power supply voltage at ECM connector C-58 or PCM connector C-55 by backprobing.
1. Do not disconnect the ECM connector C-58 or PCM connector C-55 .
2. Measure the voltage between terminal 60 or 66 and ground by backprobing.
- Voltage should be battery positive voltage.

Q: Is the voltage normal?

YES: Go to Step 6.

NO: Go to Step 4.

STEP 4. Check the backup power supply voltage at ECM harness side connector C-58 or PCM harness side connector C-55 .
1. Disconnect the ECM connector C-58 or PCM connector C-55 and measure at the harness side.
2. Measure the voltage between terminal 60 or 66 and ground.
- Voltage should be battery positive voltage.

Q: Is the voltage normal?

YES: Go to Step 5.

NO: Check connectors C-28, C-78 and C-89 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector are in good condition, repair harness wire between battery and ECM connector C-58 terminal 60 or PCM connector C-55 terminal 66 because of open circuit or short circuit to ground. Then go to Step 7.

STEP 5. Check connector C-58 at ECM or connector C-55 at PCM for damage.

Q: Is the harness connector in good condition?

YES: Check connectors C-28, C-78 and C-89 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector are in good condition, repair harness wire between battery and ECM connector C-58 terminal 60 or PCM connector C-55 terminal 66 because of open circuit or short circuit to ground. Then go to Step 7.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 7.

STEP 6. Check connector C-58 at ECM or connector C-55 at PCM for damage.

Q: Is the harness connector in good condition?

YES: Replace the PCM. Then go to Step 7.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 7.

STEP 7. Using scan tool M6991502, read the diagnostic trouble code (DTC).

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool M6991502.

1. Connect scan tool MB991502 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 the DTC P1603 is output?

YES: Retry the troubleshooting.

NO: The inspection is complete.