Distributorless Ignition System (DIS) – Replaces The Distributor

Distributorless Ignition System (DIS) - Replaces The Distributor
Distributorless Ignition System (DIS) - Replaces The Distributor

Ignition systems have evolved to a completely solid state electronic system with no moving parts.

Hence, The Distributorless Ignition System.

So, No distributor means there is no distributor cap or rotor to replace. Also, No troublesome vacuum or mechanical advance mechanisms to cause timing problems.

Distributorless Ignition Systems (DIS) are controlled by the on board computer. In place of the distributor; there are multiple coils for the new System.

The components of Distributorless Ignition System (DIS) are:

  • Ignition Coils
  • Spark Plug
  • Ignition Control Module (ICM) or Ignition Control Unit
  • Ignition Switch
  • Battery
  • Crankshaft Triggering Device
  • Camshaft Triggering Device
Distributor Ignition System Illustration
Distributor Ignition System Illustration

The evolution of ignition systems has provided a number of benefits. Even so, that does not mean they are trouble free. Failures can and do occur for a variety of reasons.

So, Knowing how to identify and diagnose common (DIS) problems can save you a lot of guesswork. This will help the next time your engine cranks but refuses to start; or one that runs but is missing.

If an engine cranks but will not start; is it fuel, ignition or compression? Ignition is usually the easiest of the three to check. On most engines all you have to do is pull off a plug wire; and check for spark when the engine is cranked. On coil-over-plug (COP) Distributorless Ignition Systems; there are no plug wires so you have to remove a coil and use a plug wire or adapter to check for a spark.

Testing The Distributorless Ignition System (DIS)

If there is no spark in one cylinder, try another. No spark in any cylinder would most likely indicate; a failed (DIS) module or crankshaft position (CKP) sensor. Many engines with electronic fuel injection also use the crankshaft position sensor signal to trigger the injectors. So, if there is no spark and no injector activity; the problem is likely in the crank position sensor. No spark in one or two cylinders that share a coil; would tell you a coil has probably failed.

The coils in a (DIS) system functions the same as those in ordinary ignition systems. So, testing is essentially the same. But, the driveability symptoms caused by a weak or dead coil will be limited; to one or two cylinders; rather than all the cylinders.

A Low (MAP) sensor output voltage; or a coolant sensor that always reads cold; will allow more spark advance than normal. This, in turn, may cause detonation (spark knock) problems when the engine is under load. Also, a faulty knock sensor (KS) or an (EGR) valve that is not working.

A High (MAP) output voltage or a misadjusted throttle position sensor can have the opposite effect. This would cause the spark control system to retard timing more than normal. Retarded timing will reduce performance and fuel economy.


Do not forget, that ordinary secondary ignition problems can also cause misfires the same as a conventional ignition system. A bad spark plug wire or a fouled spark plug will act just like a weak or bad (DIS) coil.

The evolution of ignition systems has provided a number of benefits. Drivers with newer systems enjoy better fuel efficiency, more reliable operation and reduced maintenance costs.

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