Electronic Control Unit (ECU) failure is commonly caused by a damaged regulator. The regulator transforms AC current from the generator into a DC current to load your battery. A faulty regulator will cause the ECU to receive a voltage supply that is out of its' normal range, which will cause the ECU to fail.

 

How to Test the Regulator:

1. Install the replacement ECU

2. Start the engine, but DO NOT rev it up, let the engine run idle

3. Measure the battery's voltage, a normal reading will be approximately 14 volts

4. Slowly rev up the engine, while keeping a constant eye on the battery voltage. The battery voltage should stay below 15 volts

5. If your voltage reads beyone 15 volts, stop the test immediately, a new regulator is needed.

OEM electronic control units (ECUs) are commonly damaged by worn out or defective ignition coils. Although a HT coil may still spark, if the inner coils are damaged, they will continue to accept more current than the ECU can handle. This will lead to the breakdown of the electronic control unit.

How to Check the Igntion Coil: 

1. Unplug both plugs on the ignition coil

2. Measure the resistance of the two terminals. A normal reading will be between 3 and 4.3

3. If the resistance between the two terminals is lower, then your igntion coil needs to be replaced.

 

*Only install the replacement ECU once you are positive the ignition coils are good.