Owner's Problem Description
The owner reports that the Check Engine light and brake light on their 1999 Ford Windstar remain illuminated. Despite the car running normally, it fails NYS inspection due to these warning lights. In the past, they managed to reset the system to turn off the lights, but had to drive over 70 miles for the diagnostic computer to allow for inspection. They are seeking a definitive cause and solution.
Professional Technical Analysis
The 1999 Ford Windstar is equipped with a 3.8L V6 engine and an automatic transmission, typically having around 150,000 miles. The persistent Check Engine light, alongside the brake light, indicates underlying issues that need addressing before the vehicle can pass inspection. The vehicle's PCM (Powertrain Control Module) must be scanned for trouble codes. In this case, the retrieved code P1518 indicates an issue with the Intake Manifold Runner Control (IMRC) being stuck open. This can lead to improper airflow, affecting engine performance and emissions, which are critical for passing inspection. The brake light could also be related to the ABS system; if there are stored codes from the ABS module, this could suggest issues with the braking system that need to be resolved. A thorough inspection of the brake fluid level and ABS components is essential. The vehicle's current condition is stable, but the illuminated warning lights pose a risk for inspection failure and may indicate safety concerns if the brake system is compromised. Repairing the IMRC issue should restore proper function, while the brake light issue must be diagnosed to ensure safety and compliance.
Possible Causes
Most common causes (ordered by frequency):
- Intake Manifold Runner Control (IMRC) Stuck Open: The P1518 code indicates that the IMRC is not functioning correctly, which can lead to improper air-fuel mixture and poor engine performance. This issue is frequently observed in 3.8L engines, particularly as they age. The IMRC actuator may be jammed due to carbon buildup or a failed motor that needs replacement. The expected voltage supply to the actuator should be around 5V during operation. - Check Engine light illuminated, diagnostic trouble code P1518 retrieved, potential performance issues during acceleration.
- ABS System Fault: The brake light may be triggered by an issue within the ABS system, such as low brake fluid levels or a malfunctioning ABS module. It is crucial to check for any stored codes in the ABS system that could indicate a specific fault. The ABS control module typically operates at 12V, and any faults can lead to improper brake function. - Brake light illuminated, potential stored codes in the ABS system, indication of low brake fluid or ABS module malfunction.
- Electrical Connection Issues: Corroded or loose connections within the engine management or ABS systems can lead to intermittent issues, causing warning lights to remain on. A thorough inspection of all related connectors, especially ground connections, is essential for diagnosing these electrical issues. Voltage drop tests can be performed to ensure proper circuit integrity. - Intermittent warning lights, visual inspection reveals corroded connectors, voltage drop observed during testing.
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 - OBD-II Code Retrieval: Start by scanning the PCM using a professional OBD-II scanner or GeekOBD APP to retrieve any stored codes. This includes checking freeze frame data for additional context on the conditions when the fault occurred. It is vital to document all codes and their corresponding freeze frames, as they provide critical insights into the malfunction.
- STEP 2 - ABS System Diagnostics: After addressing the PCM codes, use the scanner to check for any fault codes in the ABS system. This will help identify if the brake light issue is related to the ABS control module or low brake fluid levels. Ensure that the brake fluid reservoir is filled to the proper level before proceeding with diagnostics.
- STEP 3 - Visual Inspection: Perform a thorough visual inspection of all related wiring and connectors. Look for signs of corrosion, loose connections, or damaged wires. Pay special attention to ground connections, as these can often lead to electrical issues that trigger warning lights.
- STEP 4 - Component Testing: Test the IMRC actuator and ABS module for functionality. The IMRC actuator should receive approximately 5V when activated. The ABS module should be tested for proper response to inputs and outputs. Utilize the GeekOBD APP to monitor live data during this testing phase for real-time evaluation.
