P1107
ChryslerDual Alternator Lower Circuit Malfunction/ Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage
Medium SeverityThis code indicates either a malfunction in the lower circuit of a dual alternator system, which can impact the vehicle's charging capabilities, or an intermittent low voltage signal from the Manifold Absolute Pressure (MAP) sensor, affecting engine performance. A problem with the MAP sensor can lead to incorrect fuel mixture, while an alternator issue can result in a dead battery and vehicle shutdown.
⚠️ Before You Begin (Safety First)
Always disconnect the battery's negative terminal before performing any electrical repairs to prevent accidental shorts or injury. Allow the engine to cool down before working on any engine components to avoid burns. Wear appropriate personal protective equipment, such as safety glasses and gloves, when working on your vehicle.
Common Symptoms
- Check Engine Light illumination
- Rough idle or stalling
- Poor fuel economy
- Reduced engine power
- Engine hesitation during acceleration
- Battery warning light on dashboard
- Dim headlights or interior lights (if charging system issue)
- Dead battery (if charging system issue)
Common Causes
- Faulty MAP sensor
- Corroded, loose, or damaged wiring/connectors to the MAP sensor
- Vacuum leaks affecting MAP sensor readings
- Faulty lower alternator in a dual alternator system
- Wiring or connector issues in the dual alternator lower circuit
- Faulty voltage regulator (can be integrated with the alternator or ECM)
Frequently reported on: Chrysler 300 2005, Dodge Grand Caravan 2008, Jeep Grand Cherokee 2001, Dodge Ram 1500 2003, Chrysler Sebring 2004
Diagnostic Steps
- Locate the MAP sensor, usually on the intake manifold, and inspect its electrical connector and wiring for any signs of damage, corrosion, or looseness.
- Carefully disconnect the MAP sensor and check for bent or corroded pins. Clean if necessary and reconnect firmly.
- Inspect the vacuum hose connected to the MAP sensor (if applicable) for cracks or leaks. Repair or replace as needed.
- Use a multimeter to check the voltage signal from the MAP sensor's signal wire (refer to a service manual for expected values).
- If a dual alternator system is suspected, visually inspect both alternators and their wiring for obvious damage or loose connections.
- Check the battery voltage with the engine off and then running to ensure the charging system is functioning correctly (should be around 12.6V off, 13.5-14.7V running).
- Clear the P1107 code with an OBD-II scanner and test drive the vehicle to see if the code returns.
👨🔧 When to Call a Professional
If after checking the MAP sensor and its wiring, the issue persists, or if you suspect a charging system problem (e.g., battery light is on, dim lights, slow cranking), it is best to consult a professional mechanic. Diagnosing dual alternator systems can be complex and may require specialized tools.
Commonly Asked Questions
What is a MAP sensor and why is it important?
The Manifold Absolute Pressure (MAP) sensor measures the pressure inside the intake manifold. This data helps the engine's computer determine engine load and adjust fuel delivery and ignition timing for optimal performance and efficiency.
Can I drive with a P1107 code?
While it might be possible to drive short distances, it's not recommended. A faulty MAP sensor can cause poor engine performance, reduced fuel economy, and potential damage to other engine components over time. If the issue is with the charging system, you risk getting stranded with a dead battery.
How do I determine if P1107 is related to the MAP sensor or the dual alternator?
The symptoms often provide clues. If you experience rough idle, hesitation, or poor fuel economy without charging system warnings, focus on the MAP sensor. If you see a battery light, dim lights, or starting issues, investigate the charging system and alternators first. A diagnostic scan tool can help monitor live data from the MAP sensor.
What is the typical lifespan of a MAP sensor?
MAP sensors can last the lifetime of the vehicle, but they can fail prematurely due to electrical issues, vacuum leaks, or contamination from oil or carbon buildup. There isn't a fixed replacement interval for them.
Is it difficult to replace a MAP sensor?
Replacing a MAP sensor is generally considered an easy to medium difficulty DIY task. It typically involves disconnecting an electrical connector, removing a couple of mounting screws, and detaching any vacuum lines. Ensure you use the correct part for your specific vehicle.