how to troubleshoot dimming headlights in Tesla Outback 5th Generation (2015-2019)

Subaru Outback 5th Generation (2015-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

607 words

Problem Statement

Learn how to troubleshoot and fix dimming headlights in Tesla Outback 5th Generation (2015-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Affected Component

Electrical

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the negative battery terminal before performing any electrical work.
•Allow engine components to cool down before servicing.

Symptoms

•Headlights dimming intermittently while driving
•Headlights flickering at idle or under load
•Dashboard lights also dimming in conjunction with headlights
•Difficulty starting the car; slow cranking from the starter
•Battery warning light illuminated on the dashboard
•Increased voltage readings when using a multimeter

Diagnostic Steps

1
Check Battery Voltage: Use a multimeter to measure the battery voltage at rest and during engine operation.
2
Inspect Battery Connections: Visually inspect and tighten battery terminals and ground connections for corrosion or looseness.
3
Examine Alternator Output: Start the engine and measure the voltage at the alternator to ensure it is charging properly (usually around 13.8 - 14.4 volts).
4
Test Headlight Relay: Check the headlight relay for proper operation using a multimeter or by swapping with a known good relay.
5
Inspect Wiring and Connectors: Look for damaged wiring or corroded connectors between the battery, alternator, and headlights.
6
Scan for Diagnostic Codes: Use an OBD-II scanner to check for any stored trouble codes that might indicate electrical system issues.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Multimeter
•Socket set
•OBD-II scanner
•Wire brush
•Protective gloves

Parts Required

•New battery (if needed)
•New alternator (if needed)
•Headlight relay (if needed)

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Symptoms

•Headlights dimming intermittently while driving

•Headlights flickering at idle or under load

•Dashboard lights also dimming in conjunction with headlights

•Difficulty starting the car; slow cranking from the starter

•Battery warning light illuminated on the dashboard

•Increased voltage readings when using a multimeter

Diagnostic Steps

1
Check Battery Voltage: Use a multimeter to measure the battery voltage at rest and during engine operation.
2
Inspect Battery Connections: Visually inspect and tighten battery terminals and ground connections for corrosion or looseness.
3
Examine Alternator Output: Start the engine and measure the voltage at the alternator to ensure it is charging properly (usually around 13.8 - 14.4 volts).
4
Test Headlight Relay: Check the headlight relay for proper operation using a multimeter or by swapping with a known good relay.
5
Inspect Wiring and Connectors: Look for damaged wiring or corroded connectors between the battery, alternator, and headlights.
6
Scan for Diagnostic Codes: Use an OBD-II scanner to check for any stored trouble codes that might indicate electrical system issues.

Solution

1. Preparation

Tools Required: Multimeter, socket set, OBD-II scanner, wire brush, protective gloves.
Safety Warnings: Disconnect the negative battery terminal before performing any electrical work.

2. Battery Inspection and Replacement

Step 1: Check Battery Condition
- Inspect the battery for any signs of swelling or leakage.
- Clean the terminals with a wire brush and reconnect them securely.
Step 2: Replace Battery if Necessary
- If the battery voltage is below 12.4 volts at rest, consider replacing the battery.
- Remove the old battery by releasing the hold-down clamp and disconnecting the terminals (negative first).
- Install the new battery in reverse order of removal, ensuring a secure fit and correct terminal connection.

3. Alternator Testing and Replacement

Step 1: Test Alternator Output
- Measure voltage at the alternator with the engine running. Voltage should be between 13.8 - 14.4 volts.
Step 2: Replace Alternator if Required
- If voltage is low, disconnect the battery again.
- Remove the serpentine belt using a wrench to relieve tension on the belt tensioner.
- Unplug the alternator connector and remove the mounting bolts.
- Install the new alternator and reconnect the wiring and belt.
- Reconnect the battery and check voltage again.

4. Headlight Relay and Wiring Inspection

Step 1: Check and Replace Headlight Relay
- Locate the headlight relay in the fuse box.
- Swap with a functional relay from another circuit or replace it if faulty.
Step 2: Inspect Wiring
- Examine wiring from the battery to the headlights for any frays or damage.
- Repair or replace any damaged sections to ensure proper voltage delivery.