WIRING
We sometimes have customers calling asking why their engines don't start. After a return of the ECU, we find that it has either not been wired correctly or reverse polarity has destroyed a diode. If your wire loom has 2 separate wires for the ECU, step one is to combine them as shown here:
We do NOT believe in a fuse or breaker between the ECU and it's power source, however, we do recommend a temporary in-line fuse of 5A until all initial installation / run-ups have been completed. Be SURE to clearly mark this to be removed since the fuse WILL fail at takeoff power.
Never engage the starter by touching the starter wire to the positive battery terminal or to the positive battery BUS. It will cause a large spark and possible reverse current, damaging the ECU. Always complete the starter relay wiring before starting.
Make sure batteries are fully charged prior to the first start and if using lithium batteries with a built in battery management system, add a lead acid battery in parallelly during the first starting attempts to be sure the alternator has a load. This further protects the ECU.
NO ECU GROUND wires to be hooked up, this is done on the engine , no wires from the ECU bundle should be grounded.
if ecu power is shorted to ground
We have had a few circumstances where installers have shorted their ECU power to ground, when this happens you burn up the ECU making it unrepairable and likely damaging other 12V components on the engine. In order to protect the ECU during installation of your electrical system, it is suggested that the ECU power wires are protected with electrical tape and installed after other electrical work is completed. You might also use a 1 amp fuse (increase up to 5 amp if it keeps blowing) between the ECU power leads and the main power buss the first time power is applied (this is just a quick test to verify that there is no short and obviously should not be left in place, the ECU should remain unfused as shown in the diagram for normal operation)
Except for emergency situations you should not run the system without batteries engaged.
Do not crank the engine without the starter relay or it could introduce a large spike into the system damaging the ECU.
A symptom of a burnt up ECU is a strong electrical smell from the ECU enclosure.
You will have to replace the following on the engine if power is shorted to ground:
Your ECU
Crank Sensor
CAM Sensor
Variable Valve Timing Solenoid
Variable Valve Lift Solenoid
Coils (4)
The cost of a new ECU is $1500.00
Cost for additional items: $815.00 (subject to change) These items MUST be replaced.
None of this is to indicate that the ECU is fragile in anyway. It is just like any other electrical device where voltage reversal is not acceptable. We feel the lack of fuses increase the overall safety.