Decoding the P1487 Chrysler OBD2 Trouble Code
When your Chrysler, Dodge, Jeep, or Ram vehicle’s check engine light illuminates and a scan tool reveals code P1487, you’re dealing with a specific fault within the Evaporative Emission Control (EVAP) system. This Diagnostic Trouble Code (DTC) is manufacturer-specific, meaning its precise definition is tailored to Chrysler Corporation vehicles. In technical terms, P1487 is defined as “Leak Detection Pump Switch or Mechanical Fault”. This indicates that the vehicle’s Powertrain Control Module (PCM) has detected an irregularity in the operation or electrical circuit of the Leak Detection Pump (LDP), a critical component responsible for monitoring the fuel vapor system for leaks.
What is the Leak Detection Pump (LDP)?
The Leak Detection Pump is not a pump in the traditional sense. It’s a smart device used primarily in many Chrysler vehicles to pressurize the EVAP system for leak testing. During a self-test (usually after a cold start under specific driving conditions), the PCM activates the LDP. It uses engine vacuum to draw in air, then seals and uses a small internal electric motor to pressurize the system. A switch inside the LDP tells the PCM when pressure has been achieved. A P1487 code flags a problem with this switch signal or the pump’s ability to build pressure mechanically.
Symptoms and Causes of a P1487 Fault Code
Unlike some engine codes that cause noticeable drivability issues, P1487 is primarily an emissions-related fault. However, ignoring it can lead to a failed emissions test and potentially mask other problems.
Common Symptoms of P1487
- Illuminated Check Engine Light (MIL): The primary and most common symptom.
- Failed Emissions Inspection: The vehicle will not pass smog or emissions testing with an active EVAP code.
- Possible Fuel Odor: In some cases, a compromised EVAP system may allow fuel vapors to escape.
- No Drivability Issues: The engine typically runs normally; performance, fuel economy, and starting are usually unaffected.
Root Causes of Code P1487
Diagnosing P1487 requires a systematic approach, as the fault can be electrical, mechanical, or even due to issues elsewhere in the EVAP system.
- Faulty Leak Detection Pump (LDP): The most common cause. The internal motor, switch, or diaphragm can fail.
- Open or Shorted Circuitry: Damaged, corroded, or broken wires in the LDP control or sense circuit.
- Poor Electrical Connections: A corroded or loose connector at the LDP or PCM.
- EVAP System Blockage or Severe Leak: A completely blocked vent line or a very large leak (e.g., loose gas cap) can prevent the LDP from operating correctly, setting this code.
- Faulty Powertrain Control Module (PCM): Rare, but a malfunctioning PCM that cannot properly control or monitor the LDP can be the culprit.
Step-by-Step Diagnostic Procedure for P1487
Proper diagnosis is key to an effective repair. Avoid the temptation to just replace the LDP immediately. Follow these technical steps to pinpoint the failure.
Step 1: Preliminary Checks
Begin with the simplest and most common issues. Ensure the vehicle’s gas cap is installed correctly and is not damaged. Perform a visual inspection of the LDP (often located near the EVAP canister at the rear of the vehicle) and all associated wiring and hoses for obvious damage, disconnections, or corrosion.
Step 2: Scan Tool Data and Actuation Tests
Using a professional-grade bidirectional scan tool is highly recommended. Access the PCM data stream and look for LDP-related parameters. Command the LDP to run using the scan tool’s actuator test function. Listen for a clicking or humming sound from the pump. If it doesn’t activate, you have an electrical supply, ground, or control issue.
Step 3: Electrical Circuit Testing
If the LDP doesn’t activate, consult a vehicle-specific wiring diagram. Key checks include:
- Power Supply: Check for battery voltage at the LDP connector with the ignition ON.
- Ground Circuit: Verify the ground path has continuity and is clean.
- Control Circuit: Use a noid light or multimeter to see if the PCM is providing a pulsed ground signal to activate the pump during a command test.
- Switch Circuit: Test the continuity and signal from the internal switch as the pump operates (may require special tools).
Step 4: Mechanical and Vacuum Testing
If the LDP activates electrically but the code persists, the issue is likely mechanical. Disconnect the hoses from the LDP. Check for unobstructed airflow through the pump’s ports according to the service manual procedure. Use a hand-held vacuum pump to test the integrity of the pump’s diaphragm and check valves. A pump that cannot hold vacuum is faulty.
Repair Solutions and Replacement Guide
Once the faulty component is identified, proceed with the repair. Always clear the DTCs after repair and perform a complete drive cycle to ensure the code does not return.
Replacing the Leak Detection Pump
If testing confirms a bad LDP, replacement is straightforward. Locate the pump, disconnect the electrical connector, carefully label and disconnect the vacuum hoses, unbolt the mounting bracket, and install the new unit. Always use OEM or high-quality aftermarket parts to ensure compatibility and longevity. Reconnect all hoses precisely as they were.
Repairing Wiring and Connections
For wiring faults, repair any damaged wires using solder and heat shrink tubing—never use twist-on connectors in automotive environments. Clean all electrical contacts with electrical cleaner and apply dielectric grease to prevent future corrosion.
Addressing Related EVAP Issues
If a blockage or large leak was found (e.g., at the canister, purge valve, or fuel tank), these components must be addressed. A smoke machine test is the most effective way to locate external EVAP leaks after the LDP is confirmed to be functional.
Conclusion: Ensuring a Permanent Fix
Code P1487 on Chrysler vehicles is a precise indicator of a fault in the leak detection subsystem. While it may not strand you on the side of the road, it is a critical emissions fault. A methodical diagnostic approach—starting with visual checks, moving to electrical tests with a multimeter and scan tool, and finishing with mechanical verification—will save time and money by ensuring the correct component is replaced. After repairs, a successful drive cycle completion without the check engine light returning is the ultimate confirmation of a job well done, restoring your vehicle’s emissions system to proper working order and ensuring it is ready to pass inspection.