Hardware & BigComm Software Instruction Manual

BigStuff3 Pro SEFI System
Version 2.1 – February 2011 14
Points – (Single white wire)
Do not connect this wire if a factory ignition system is being used. This is the GEN3’s "points" signal
wire. It needs to be connected to the "points" output connection from the aftermarket ignition module,
e.g. MSD 6A box.
 Note : Applying 12V to the BS3 points wire will immediately damage the GEN3 ECU!
Back_to_Points
12V Switched – (Single pink wire)
A secure connection must be made to a switched 12V supply. The best sourceis a switched 12V
supply at the vehicle fuse block. Twelve volts (12V) must be present on this wire during and after
cranking. If the 12V supply does not remain during and after
cranking, the ECU will not power up and the engine will not start
and/or remain running. A simple way to determine if a live 12V
supply exists during cranking is to check it with an voltmeter.
Securely fasten the voltmeter’s red (+ positive) wire to the ignition input on the fuse block. Secure the
voltmeter’s black wire (- negative) to a adequate ground location. Crank the engine and the voltage
meter should indicate an output of between 12 to 14 volts. If the output voltage is below 12 volts,
check to make sure the battery is fully charged and all the cells of the battery are functioning properly.
NOTE: If the engine cranks, but does not start make sure the battery voltage is at or above 12V
during cranking. Low battery voltage conditions must be fixed prior to starting the engine.
Battery voltage (especially during cranking) is even more important with coil-on-plug
applications. Back_to_Switch_Ignition
Positive and Negative Battery Connections – (Four (4) 3/8” ring terminals. Two (2) red
wire terminals and two (2) black wire terminals)
The GEN3 main wire harness ground cables
and the ignition system must BOTH be grounded to
the same negative post of the same battery!! Failure to run the ground cables from both these
systems directly to the battery will cause performance issues and potentially damage one or both of the
electronic systems. No other ground paths/solutions are acceptable!
To avoid ground loop issues, and the hours of frustration that come with them, ground the BS3 and
MSD systems directly to the battery!!
Also, do not splice any other ground wires (from other systems/components) into either the ignition or
BS3 ground cables.
The BigStuff3 GEN3 system 12V power cables can
be connected to the vehicle cut-off switch.
Power for the BigStuff3 GEN3 system and the ignition system should also be from the same source
(the battery or the cutoff switch).