Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

LS3 harness for motec

EFI Wiring Fundamentals

Forum Posts



Tech Articles

Discussion and questions related to the course Motorsport Wiring Fundamentals

= Resolved threads


I'm planing to build my own LS3 harness for LS3 engine for motec M84

and I'm want to know how to connect my sensors and coil packs and I have come douts about it

crank position sensor (ref ) I connect it to ( 0V ,signal, 5V ) is the source 5V or 12 V ?

cam positon sensor (sync) (0V ,signal , 5v) is the source 5V or 12V ?

about bank 1 and 2 coil pack and connector have 7 wires (A,B,C,D,E,F,G,H) , ( A )gose to GND , D not used, H gose to 12V power supply how I connect the rest of wires regarding the fire order ?

My LS3 harnesses have used 5V for both Crank and Cam. There are two different sensors that have the wiring slightly swapped. I believe the current crate engines are coming with the gray 58 tooth crank sensors, wiring is A=Signal, B=Ground, C=Power. Same order for the Cam connector.

The coil packs are:

Bank 1:

A - Power Ground, B - Ign Cyl 7, C - Ign Cyl 5, D - N/C , E - Signal Ground, F - Ign Cyl 3, G - Ign Cyl 1, H - Ignition Power

Bank 2:

A - Power Ground, B - Ign Cyl 2, C - Ign Cyl 4, D - N/C , E - Signal Ground, F - Ign Cyl 6, G - Ign Cyl 8, H - Ignition Power

With the M84, you have to wire the ignition outputs in firing order. The LS3 firing order is 1-8-7-2-6-5-4-3.

You would be advised to get a factory service manual for the engine so you have a wiring diagram of the stock harness.

thanks for your information

the wiring loom from motec connect sync sensor and ref sensor with 8V do I have to change it to 5v or I keep it the same ?

I'm sure it will work with 8V, that is a stable reference voltage.