Owner's Problem Description
The owner reports that their 2000 Chrysler Cirrus just stopped running while driving. After this incident, they replaced the fuel pump, but the vehicle still won't start. The owner also replaced the distributor, but there is no spark at the distributor. Fuel pressure is confirmed to be good, and the timing belt is intact. Despite cranking, the engine does not start, and there are no diagnostic trouble codes present. They are seeking further diagnostic steps and wiring schematic information.
Professional Technical Analysis
The vehicle in question is a 2000 Chrysler Cirrus equipped with a 2.4L inline-4 engine, approximately 120,000 miles. The owner experienced a sudden engine stall during operation, followed by a no-start condition despite replacing both the fuel pump and the distributor. Fuel pressure readings indicate a stable range of 35-45 PSI, which is within specification. The timing belt has been visually confirmed to be intact and properly aligned. The absence of spark at the distributor suggests a potential issue in the ignition system, specifically the ignition coil or the power supply to the ignition components. Analyzing the system interconnections, the ignition coil requires a stable reference voltage from the powertrain control module (PCM) to generate a spark. Diagnostic data from the Snap-on scan tool indicates proper crank and cam signals, yet voltage readings at the distributor's wiring harness (4.9V and 8V) are insufficient for normal operation, hinting at possible wiring issues or component failures. The absence of any DTCs complicates the diagnosis, requiring a detailed inspection of the ignition system wiring and the automatic shutdown (ASD) relay function. Current vehicle condition shows that while cranking, the engine turns over, but fails to ignite, indicating potential electrical failures or fuel delivery issues that have not been fully resolved. Safety concerns include ensuring that proper voltage levels are maintained to avoid further component damage.
Possible Causes
Most common causes (ordered by frequency):
- Ignition Coil Failure: The ignition coil may have failed, preventing the generation of a spark. Testing the coil's primary and secondary resistance is essential, with specifications typically being 0.5-1.5 ohms for primary and 6,000-12,000 ohms for secondary. If the coil fails to meet these specifications, it should be replaced. Additionally, check for consistent voltage supply to the coil, which should be around 12 volts during cranking. - No spark at the distributor, confirmed good fuel pressure, and proper crank/cam signals.
- Wiring Issue: The wiring between the ignition components and the PCM could be damaged or corroded, leading to inadequate voltage supply. Testing the integrity of the dark green/orange wire and other related wiring for continuity and voltage drop is crucial. If any breaks or high resistance is found, repair or replace the affected wiring. - Measured 4.9V and 8V at the distributor connector, indicating possible wiring issues.
- ASD Relay Malfunction: The Automatic Shutdown (ASD) relay may not be providing power to the ignition system. Testing the relay for proper operation, including checking for battery voltage at the relay terminals, is essential. If the relay fails to engage or provide voltage, it should be replaced. The ASD relay should have battery voltage during cranking. - No power to the ignition system during cranking, indicating possible ASD relay failure.
- Camshaft or Crankshaft Sensor Fault: Though current data shows cam and crank signals, intermittent faults can still occur. Testing the resistance of the cam and crank sensors (typically 500-1,500 ohms) can reveal faults. If either sensor is outside of specification, it should be replaced. - Confirming sensor data does not rule out intermittent faults; potential stored codes P0340/P0335 if sensors are faulty.
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 - Initial Voltage Check: Begin by checking the voltage at the ignition coil connector while cranking the engine. The voltage should be approximately 12 volts. If voltage is present, proceed to test the ignition coil for primary and secondary resistance. This will help determine if the coil is functioning properly.
- STEP 2 - Wiring Inspection: Inspect the wiring harness for any visible damage, corrosion, or loose connections, particularly focusing on the dark green/orange wire. Use a multimeter to check for continuity and measure voltage at various points in the circuit, ensuring that power is being delivered correctly.
- STEP 3 - ASD Relay Testing: Test the ASD relay by checking for battery voltage at the relay terminals while cranking. If the relay does not have voltage or fails to engage, replace it. Ensure that the relay clicks during operation, indicating it is functioning correctly.
- STEP 4 - Sensor Resistance Check: Test the camshaft and crankshaft sensors for resistance. The readings should be between 500-1,500 ohms. If either sensor is out of range, replace it. This ensures that both sensors are functioning correctly and providing accurate signals to the PCM.
