P1105
ChryslerThe Powertrain Control Module (PCM) detects a voltage output issue with the upper alternator in a dual alternator system. This code is specific to Chrysler vehicles.
High SeverityThis code indicates that the Powertrain Control Module (PCM) has detected a problem with the charging output of the secondary or upper alternator. This can lead to undercharging of the battery, potentially causing electrical system malfunctions or a complete vehicle breakdown.
⚠️ Before You Begin (Safety First)
Always disconnect the battery's negative terminal before working on any electrical components, especially alternators, to prevent electrical shocks or short circuits. Allow engine components to cool down before handling.
Common Symptoms
- Battery warning light illuminated
- Dim headlights or interior lights
- Slow engine cranking or difficulty starting
- Malfunctioning electrical accessories
- Unusual noises from the alternator (whining or grinding)
Common Causes
- Faulty upper alternator
- Damaged or corroded wiring or connections to the upper alternator
- Faulty voltage regulator (often integrated with the PCM or alternator itself)
- Issues with the Powertrain Control Module (PCM) (less common)
Frequently reported on: Dodge Ram 2500 2005, Chrysler Pacifica 2007, Dodge Sprinter 2008, Jeep Grand Cherokee 2006, Dodge Durango 2004
Diagnostic Steps
- Inspect all visible wiring and connections to the upper alternator for signs of corrosion, fraying, or looseness.
- Check the serpentine belt for proper tension and condition; a slipping belt can reduce alternator output.
- Test the battery's voltage with the engine off and running; look for a significant difference in voltage when the engine is running compared to off.
- If comfortable, test the output of the upper alternator with a multimeter to verify it is producing adequate voltage and amperage.
- Consider having the battery fully charged and retested, as a weak battery can sometimes mask charging system issues.
- Clear the code and drive the vehicle to see if the P1105 returns, indicating an intermittent issue or a hard fault.
- If the vehicle has a separate voltage regulator, inspect its connections and consider testing it according to manufacturer specifications (if accessible and testable).
👨🔧 When to Call a Professional
If the battery warning light illuminates on your dashboard, or if you lack experience diagnosing complex electrical charging systems, it is best to consult a certified mechanic immediately to prevent further damage or a breakdown.
Commonly Asked Questions
What does P1105 mean for a Chrysler vehicle?
P1105 indicates a 'Dual Alternator Upper Fault' specifically for Chrysler vehicles, meaning the Powertrain Control Module (PCM) has detected a problem with the secondary or upper alternator's output. It signals an issue with the vehicle's charging system. You may experience electrical issues or a dead battery.
Can I drive my car with a P1105 code?
It is not recommended to drive your vehicle for an extended period with a P1105 code, as it signifies a charging system problem. Driving too long could lead to a dead battery, leaving you stranded, or potentially damaging other electrical components due to unstable voltage. Get it inspected as soon as possible.
How can I confirm if the upper alternator is faulty?
You can confirm a faulty upper alternator by performing a charging system test. This involves checking the battery voltage with the engine off and running, and then testing the output voltage and amperage directly at the upper alternator using a multimeter. An auto parts store may also be able to test the alternator off the vehicle.
Is it safe to replace just one alternator in a dual alternator system?
Yes, if only one alternator is faulty, it is generally safe to replace just the defective unit. However, it's a good practice to ensure the other alternator is functioning correctly and that there are no underlying issues like wiring problems affecting both units. Ensure the replacement alternator is the correct type and rating.
What other components should I check if I have a P1105 code?
Beyond the upper alternator itself, you should inspect the battery, the serpentine belt, all associated wiring and connectors for corrosion or damage, and the voltage regulator. In some Chrysler models, the voltage regulator is integrated into the Powertrain Control Module (PCM), which would make diagnosis more complex.