No Spark From Coil to Distributor: What’s Going Wrong and How to Fix It

No spark from the ignition coil to the distributor is most often caused by loss of coil power or ground, a missing trigger signal (from the ignition module, pickup, or crank sensor), a failed ignition coil, an open ballast resistor/resistor wire, or a bad high-tension coil lead/corroded coil tower. In practice, confirming coil voltage, checking for a pulsed ground at the coil while cranking, and verifying distributor rotation will quickly narrow the fault.

How This Ignition Link Is Supposed to Work

In a traditional distributor system, battery voltage feeds the coil’s primary winding. An ignition module (or breaker points) rapidly grounds and ungrounds the coil negative terminal to create a collapsing magnetic field, inducing high voltage in the coil’s secondary winding. That high voltage exits the coil tower via the thick “coil wire” to the center of the distributor cap, where the rotor sends it on to each spark plug. If there’s no spark reaching the distributor, the break is in coil power, coil control, the coil itself, or the high-voltage path out of the coil.

Most Common Causes

The following are the most frequent reasons you’ll see no spark from the coil to the distributor, with clues that help pinpoint each issue.

• No coil primary power: Blown fuse, failed ignition switch feed, bad ASD/main relay (common on Chrysler/Jeep), or an open ballast resistor/resistor wire prevents 12V from reaching the coil.
• No trigger to coil negative: Failed ignition module/igniter (GM HEI, Ford TFI, Toyota igniter), bad distributor pickup (magnetic or Hall sensor), failed crankshaft position sensor, or a distributor that isn’t turning (broken timing belt/chain or sheared distributor gear).
• Bad ignition coil: Open/shorted windings, internal breakdown when hot, or a cracked coil tower that leaks spark to ground.
• High-tension path fault: Defective coil wire, excessive resistance, poor connections, carbon tracking, moisture, or corrosion at the coil tower or cap center.
• Ground issues: Weak battery grounds, missing engine-to-chassis strap, corroded module/ECU grounds causing erratic or no coil control.
• Security/aftermarket wiring interference: Immobilizer cutting coil feed or an alarm/remote-start “kill” splice leaving the circuit open.
• Points/condenser faults (older systems): Burned or misadjusted points, shorted condenser, incorrect dwell, or a failed ballast/resistor wire.

Because multiple components must work in sequence, a single break—power, control, the coil itself, or the high-voltage exit—can stop spark at the source. A few simple checks can isolate which link failed.

Step-by-Step Diagnosis

Use these steps in order; each builds evidence toward the root cause and avoids guesswork and unnecessary parts.

1. Verify cranking speed and tach signal: A very slow crank or dead tach often indicates the ECU/module isn’t seeing rotation. Low battery voltage can also drop coil output.
2. Test for spark directly from the coil: Remove the coil wire from the distributor cap, attach a spark tester or spare plug grounded to the engine, and crank.
   – If you have a strong, blue spark from the coil, the issue is downstream (coil wire, cap/rotor, or plug wires).
   – If there’s no spark here, focus on coil power, control, or the coil itself.
3. Check coil positive voltage: With key ON and while cranking, measure voltage at the coil “+” terminal.
   – You should see battery voltage (or slightly less if a ballast is in circuit).
   – On many systems, a “crank bypass” feeds full battery voltage during cranking—if that circuit or the ballast fails, you may have no spark while cranking or only while running.
4. Check for a pulsed ground at coil negative: Clip a test light or LED probe to battery positive and probe the coil “−” while cranking.
   – A flashing light indicates the module/points are triggering; no flash means no trigger—suspect the module/igniter, pickup, CKP, or a non-spinning distributor.
5. Measure coil resistance: With the engine off and coil disconnected, check primary resistance (typically ~0.4–3 Ω depending on design) and secondary resistance (often 6k–15k Ω). Values far out of spec point to a bad coil.
6. Inspect the high-voltage path: Check the coil tower and coil wire for cracks, carbon tracking, moisture, or high resistance. Replace any suspect wire or cap center contact.
7. Confirm distributor rotation: Remove the cap and watch the rotor while cranking. No movement suggests a broken timing belt/chain, sheared distributor gear/pin, or a stripped drive—no trigger means no spark.
8. Test the pickup/module:
   – Magnetic pickup: Expect a few hundred ohms across leads and an AC voltage signal (often 0.2–1.0 V AC) while cranking.
   – Hall sensor: Verify 5V reference, good ground, and a switching signal (square wave) on the output.
   – Modules/igniters can fail hot; if spark returns when cool, suspect heat-soak failure (e.g., Ford TFI, GM HEI, Toyota igniter).
9. Verify grounds and power paths: Clean and tighten engine block grounds, module grounds, and ECU grounds. Check related fuses and relays (ASD/main relay on Chrysler/Jeep; ignition relay on others).
10. Consider security/aftermarket issues: Factory immobilizers and aftermarket alarms often interrupt coil power; inspect splices and restore proper wiring if needed.
11. If points-style: Set point gap/dwell, replace burned points/condenser, and confirm the ballast/resistor wire isn’t open. Ensure the coil is the correct type for a ballast/no-ballast setup.

By verifying power, trigger, and the high-voltage path in that order, you’ll quickly determine whether the failure is upstream control, the coil itself, or the physical delivery of spark to the distributor.

System-Specific Notes

Points Ignition (Pre-1975, Many Classics)

Burned or misadjusted points (incorrect dwell) and failed condensers are common no-spark culprits. Ensure the ballast resistor/resistor wire is intact and that you’re using a coil matched to a ballast system. A bypass circuit usually feeds full voltage during cranking; if the starter “I” terminal or bypass wiring fails, there may be no spark while cranking but spark when the key returns to ON.

Electronic Distributor Ignition (GM HEI, Ford TFI, Toyota/Nissan Igniters)

Modules/igniters frequently fail under heat. A weak or missing pickup signal (magnetic/Hall) will stop the coil from triggering. On some vehicles, the ECU must see a valid crank signal to power the coil circuit via a main/ASD relay; a dead CKP or relay means no coil power and no spark.

Modern Distributorless/Coil-On-Plug

If your vehicle has no distributor, this article’s “coil-to-distributor” path doesn’t apply. No-spark diagnosis shifts to coil drivers, individual coils, and crank/cam correlation via the ECU.

Quick Tools and Helpful Specs

The right tools make diagnosis faster and safer. Here’s what typically works best for coil/distributor systems.

• Adjustable spark tester or spare plug for safe, repeatable spark checks
• Digital multimeter for voltage, resistance, and AC pickup signal checks
• 12V test light or LED probe to see coil negative pulsing while cranking
• Feeler gauge/dwell meter for points systems
• Scan tool (where applicable) to watch RPM during crank and check for CKP/CMP faults
• Oscilloscope (optional) for viewing pickup/module waveforms under load

With these basics, you can validate power supply, triggering, and coil output without disassembling half the engine.

Safety and Handling

Ignition systems can exceed 30,000 volts. Follow these precautions during testing.

• Use insulated tools and a proper spark tester; avoid holding bare plug wires.
• Keep fuel vapors away from open spark testing areas.
• Disable fuel injection or pull the fuel pump relay if prolonged cranking is required.
• Secure the vehicle in Park/Neutral with the parking brake applied.

Working methodically and safely prevents shocks, fires, and damage to sensitive electronics.

When to Suspect the ECU

ECUs rarely fail compared with sensors, modules, or wiring. Consider an ECU only after confirming stable power/grounds, valid pickup/CKP signals, and a known-good module/igniter. If the ECU isn’t commanding coil control despite correct inputs and power, or if coil control returns when swapping a known-good ECU, then replacement or repair may be warranted.

Costs and Time

Typical DIY diagnosis takes 30–90 minutes with basic tools. Common parts prices (ballpark): coil wire $10–$30, ignition coil $30–$120, pickup $25–$90, module/igniter $50–$250, crank sensor $30–$120, distributor gear/repair varies. Professional diagnosis often runs 0.5–1.0 labor hours; complex wiring or timing failures can add time.

Summary

No spark from the coil to the distributor almost always traces to one of four areas: no coil power, no trigger at coil negative, a failed coil, or a fault in the high-voltage exit (coil wire/tower). Check coil voltage, verify a pulsed ground while cranking, confirm distributor rotation and pickup/module health, and inspect the coil wire and tower. With a systematic approach, you can isolate the failure quickly and restore spark confidently.

What would cause no spark from a coil?

If any of the coils show a weak or no spark, they will need to be replaced or the wiring repaired. Investigate other potential causes like a malfunctioning ignition switch, a blown fuse, a defective PCM, or a slipped or broken timing belt. While these are less common, they could still be reasons for the lack of spark.

How to check spark from coil to distributor?

To check for spark from the coil to the distributor, disconnect the main coil wire (the high-tension lead) from the distributor, hold its end near a grounded metal object using insulated pliers, and have someone crank the engine. A strong, visible, blue spark indicates the coil is working and sending a signal, suggesting a problem in the distributor cap, rotor, or spark plug wires. If there’s no spark, you need to test the power to the coil and the coil’s ability to switch the spark.
 
What You’ll Need: 

• Insulated Pliers: To safely hold the coil wire
• Spark Indicator/Tester (Optional): A specialized tool for easier observation
• A Good Ground: A metal part of the engine block

Steps to Test for Spark:

1. Locate the Coil Wire: Find the main, thick wire that runs from the ignition coil to the distributor. 
2. Disconnect the Wire: Carefully pull the wire’s boot off the distributor’s center post. 
3. Position for Observation: Using insulated pliers, hold the metal end of the disconnected wire close to a good metal ground (like the engine block), ensuring there’s a small gap for the spark to jump. Do not touch the engine directly with your bare hand. 
4. Crank the Engine: Have an assistant crank the engine for a few seconds. 
5. Observe for Spark: Look for a strong, blue spark jumping from the wire’s tip to the ground. 

Interpreting the Results:

• You See a Strong Spark: The ignition coil is working correctly. The issue is likely in the distributor cap, the rotor, the spark plug wires, or the spark plugs themselves. 
• No Spark or a Weak Spark: The problem is with the ignition coil or its power supply. 
  • No Power to the Coil: If there’s no spark, the next step is to check for power at the coil’s positive terminal using a 12-volt test light while the ignition is on. 
  • No Coil “Switching” Signal: If there’s power to the coil, you’ll need to check the switching mechanism. For older systems, this involves testing the points and condenser. For newer systems, you’d test the igniter or control module that controls the coil’s ground. 

Important Safety Tip: Always use a tool with insulated handles, like insulated pliers, to avoid electric shock when working with ignition systems.

What causes no spark to distributors?

No spark from a vehicle’s distributor is most often caused by a faulty distributor cap or rotor, a defective ignition module, or issues with the ignition coil or wiring. A basic check involves inspecting the distributor cap for damage or corrosion and ensuring the ignition coil is receiving power. More specific diagnosis might require checking the condition of spark plug wires and using a test light or multimeter to test for spark at the coil and measure resistance across components like the coil.
 
This video demonstrates how to check for spark at the ignition coil: 56sEricTheCarGuyYouTube · Dec 23, 2009
Common Causes for No Spark

• Distributor Cap and Rotor: Opens in new tabThese components distribute the high-voltage current to the spark plugs. Damage, corrosion, or moisture within the cap or on the rotor can disrupt this process. 
• Ignition Module: Opens in new tabThe electronic control module in the distributor can fail, leading to a lack of spark. 
• Ignition Coil: Opens in new tabA faulty ignition coil won’t produce the necessary high voltage. 
• Wiring and Connections: Opens in new tabDamaged or corroded wiring, a bad ignition switch, or poor connections can prevent power from reaching the distributor. 
• Points and Condenser (Older Vehicles): Opens in new tabIn points-style ignition systems, worn points or a faulty condenser can prevent the coil from firing. 

Troubleshooting Steps

1. Inspect the Distributor Cap and Rotor: Remove the cap and visually inspect it for cracks, damage, corrosion, or signs of moisture. Check the rotor for damage as well. 
2. Check the Ignition Coil: 
   • Power: Verify that the ignition coil is receiving power from the ignition switch and other wiring. 
   • Spark (for older points systems): Use a non-metallic item to manually open the points while the coil is energized to see if the coil fires. 
3. Check Spark Plug Wires: Ensure the spark plug wires are in good condition and properly seated in the distributor. 
4. Test the Ignition Module (if applicable): For systems with an ignition module, you may need to check its resistance with a multimeter. 
5. Seek Professional Diagnosis: If these steps don’t identify the problem, it’s recommended to take your car to a qualified mechanic for accurate diagnosis. 

This video explains how to diagnose a HEI distributor for no spark: 57sSnow Family RacingYouTube · Jul 19, 2023

Does spark go from coil to distributor?

When you turn the key in the ignition switch, it sends an electrical signal to the ignition coil, which then generates a high-voltage pulse. This pulse is sent to the spark plugs via the distributor or ignition module, which creates a spark that ignites the fuel-air mixture in the cylinders.