P1108
ChryslerThe Powertrain Control Module (PCM) has detected a malfunction in the circuit that controls the battery warning lamp for the dual alternator system.
Medium SeverityThis code indicates an electrical problem within the warning lamp circuit for your vehicle's dual alternator charging system. This means the battery light on your dashboard may not illuminate correctly to warn you of a charging system fault, potentially leading to a dead battery if a primary alternator fails unnoticed.
⚠️ Before You Begin (Safety First)
Always disconnect the battery's negative terminal before working on electrical components to prevent short circuits and electrical shock. Ensure the vehicle is off and has cooled down sufficiently. Wear appropriate safety gear, including gloves and eye protection.
Common Symptoms
- Battery warning lamp does not illuminate during ignition self-test.
- Battery warning lamp remains off when it should be on, even if a charging fault exists.
- Intermittent or flickering battery warning lamp.
- Possible low system voltage if an actual charging fault is present but not indicated.
- Other dashboard warning lights may appear if overall system voltage is incorrect.
Common Causes
- Faulty wiring or corroded connectors in the battery lamp control circuit.
- A defective instrument cluster where the battery warning lamp resides.
- A faulty Powertrain Control Module (PCM) or Totally Integrated Power Module (TIPM) internally.
- One or both alternators failing to correctly signal their status to the PCM.
- A blown fuse related to the instrument cluster or the charging system's warning circuit.
Frequently reported on: Ram 2500 2010-2018, Ram 3500 2010-2018, Dodge Sprinter 2006-2009, Ram ProMaster 2014-2020
Diagnostic Steps
- Visually inspect all visible wiring and electrical connectors associated with both alternators and the instrument cluster for any signs of damage, corrosion, or looseness.
- Locate and check all fuses related to the instrument cluster and the charging system, replacing any blown fuses with new ones of the correct amperage.
- Perform a basic battery voltage test with the engine off (should be around 12.6V) and with the engine running (should be between 13.5V and 14.5V) to ensure the charging system is currently functional.
- If you have access to an advanced scan tool, monitor the status of the battery lamp circuit signal from the PCM to look for inconsistencies.
- Consider performing an instrument cluster self-test (refer to your vehicle's service manual) to verify the functionality of all dashboard warning lights.
👨🔧 When to Call a Professional
If the battery light is on or flickering persistently, or if you notice any other signs of charging system trouble (like dimming lights or difficulty starting) in conjunction with P1108, seek professional diagnosis immediately. A failing charging system can leave you stranded.
Commonly Asked Questions
What does P1108 mean for my Chrysler vehicle?
P1108 for Chrysler indicates a malfunction in the electrical circuit that controls the battery warning light specifically for your vehicle's dual alternator system.
Can I drive with a P1108 code?
While the code itself points to an issue with the warning light circuit, it's critical to ensure your vehicle's charging system is actually working. If the battery light is on, flickering, or you suspect a charging problem, driving can lead to a dead battery and being stranded. Address it promptly.
How do I check for a blown fuse related to P1108?
Refer to your vehicle's owner's manual or a service manual to identify the fuse boxes (usually under the hood and/or dashboard) and locate fuses associated with the instrument cluster, alternators, and charging system. Visually inspect fuses for a broken wire, or use a multimeter to check for continuity.
Does P1108 mean one of my alternators is bad?
Not directly. The code specifically points to the battery lamp circuit, not necessarily the alternators' ability to charge. However, an alternator issue could indirectly cause the PCM to trigger this code if it affects the warning lamp signal.
Is P1108 a common problem on Ram trucks?
P1108 is specific to Chrysler/Dodge/Ram vehicles equipped with dual alternators. While not universally common, it can occur in these specific configurations due to wiring issues, instrument cluster faults, or PCM communication problems.
What tools do I need to diagnose P1108?
At a minimum, you'll need a multimeter for checking voltage and continuity, a basic OBD-II scanner, and potentially an advanced scan tool capable of monitoring live data for the charging system and instrument cluster.