Owner's Problem Description
The owner reports that their 2003 Dodge Intrepid was running well until the battery light illuminated, followed by the ABS light while driving. The radio turned off completely, and the RPMs stayed high with some hesitation. After driving about 7 miles the next morning, the ABS light and radio continued to cycle on and off, and the check engine light came on with a P0700 code. The owner mentions an existing oil leak due to a wrong drain plug. They're seeking suggestions for diagnosing the issue.
Professional Technical Analysis
The vehicle in question is a 2003 Dodge Intrepid equipped with a 3.5L V6 engine, approximately 120,000 miles on the odometer. The owner describes a sequence of electrical failures starting with the battery light, followed by intermittent ABS light activation, and ultimately the check engine light with a P0700 code. This code indicates a transmission control system issue, which might be related to the charging system malfunction. The observed symptoms, including high RPMs and hesitations, suggest that the vehicle's electrical system is failing, likely due to insufficient voltage being supplied to the vehicle's modules. The charging system should be scrutinized, specifically the alternator and related connections. If the alternator is not maintaining a voltage between 13.8-14.4V under load, it could cause erratic behavior in several systems including the PCM (Powertrain Control Module), which could lead to transmission issues and erratic engine performance. The presence of an oil leak could also complicate matters, potentially affecting sensor operation or electrical connections if oil reaches wiring harnesses. A thorough examination of the alternator's output, battery condition (including load testing), and all associated wiring is essential for accurate diagnosis. There are indications that the alternator may need replacement, especially if the brushes are worn or if internal components are failing. Given the age and mileage of the vehicle, such failures are not uncommon. Additionally, the P0700 code should be further investigated with a focus on related transmission fault codes that may be stored.
Possible Causes
Most common causes (ordered by frequency):
- Charging System Failure: The alternator is not producing adequate voltage, potentially due to worn brushes or internal component failure. The output voltage should be between 13.8-14.4V under load. If the voltage drops below this range, it can cause multiple electrical system failures leading to various warning lights and erratic engine behavior. Testing should include measuring the output voltage at idle and under load with accessories turned on. - Battery light and ABS light activation, intermittent electrical failures, voltage readings below 13.8V during testing.
- Ignition Control Module (ICM) or PCM Malfunction: If the ICM or PCM is overheating or failing, it can affect engine performance and cause high RPMs and hesitation. The P0700 code indicates a transmission-related issue which could stem from electrical faults affecting the PCM. Testing the ICM's functionality at different temperatures is essential to determine if it's failing. - Symptoms of high RPM and hesitation, stored P0700 code, possible overheating of control modules.
- Oil Leak Impacting Electrical Connections: The existing oil leak from a wrong drain plug could have reached electrical connections, leading to intermittent failures. If oil seeps into wiring harnesses or connectors, it may disrupt signal integrity and cause erratic operation of various systems. Inspecting the integrity of wiring and connectors near the leak is necessary. - Signs of oil leakage, potential damage to wiring or connectors, intermittent electrical issues.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Conduct an OBD-II Scan: Start with a complete OBD-II scan using GeekOBD APP or a professional scanner to retrieve the P0700 code and any additional stored codes. Pay attention to freeze frame data which can provide context for the fault. This initial step is crucial for understanding the scope of the issue.
- STEP 2 - Test Charging System Voltage: Measure the alternator output voltage with a multimeter while the engine is running. The voltage should be between 13.8-14.4V at idle and remain stable under load conditions. If the voltage fluctuates or is below this range, the alternator should be further inspected or replaced.
- STEP 3 - Inspect Electrical Connections: Check for any signs of oil contamination around electrical connections, especially those related to the PCM and ICM. Ensure all connectors are secure and free of corrosion. Use dielectric grease to protect connections if necessary.
- STEP 4 - Road Test with Live Data Monitoring: Perform a road test while monitoring live data using GeekOBD APP. Pay attention to voltage stability, engine performance, and any active fault codes during operation. This will help confirm if the issue persists under driving conditions.
