FREQUENTLY ASKED QUESTIONS
Where does the single red wire in the relay and fuse block center go?
This is what 'powers up' the PCM. Its important that this key hot power, along with power to injectors, coils, and so on, STAY HOT when cranking over the engine. Some accessory positions on key switches ARE NOT HOT when cranking. This also includes older vehicles that had POINTS ignition. Even the COIL wire on some of those went dead when cranking. This is because when cranking the coil was boosted to 12v+ through the R terminal on the starter solenoid. After cranking, power was restored to the coil through a resistor
Where can I install my coolant temperature gauge sender?
How do I wire my speedometer up?
Connect the black thats coiled within the "under dash" wires to the speedometer. NOTE: DO NOT tap into the VSS signal of the harness. This will cause the transmission to shift improperly.
What is the TCC brake wire for?
How do I get my tachometer to work?
Vortec 4.8/5.3/6.0 this comes from the PCM, which generates this signal for a aftermarket tachometer. The stock LS tach signal is 4 cylinder type signal. This can be programmed as 4, 6, or 8 cylinder signal. Some 2003+ LS PCM's tach signal is not strong enough, and needs boosted. Please see diagram in the provided instructions.
Does all the grounds need to be connected to a ground source?
All of the grounds within the harness should be connected to a good ground source before attempting to crank the motor.
Do I need to plug in the VSS connector if I am using a 350/400/manual transmission?
How do I wire up my fuel pump?
If using a 350/400 transmission where do I get vacuum for the vacuum modulator?
Do you make harnesses for any other engines?
We only support GM LSx. We do not support any other types of engines.
Do you make a harness for my specific vehicle?
What is Drive-By-Wire (DBW)?
The typical throttle body that had a braided cable attached to the gas pedal for acceleration changed in 2003 on the vortec/truck motors. The 2003 vortec/truck motors throttle body blade is controlled by an electric motor. The gas pedal is basically an sensor that sends a signal to the TAC (throttle actuator control) module. The TAC module and the PCM work together for control of the throttle blade within the throttle body. If you buy a vortec/truck motor from a 2003 and up, make sure you get the Gas Pedal Assembly, PCM and the TAC module (throttle actuator control). Those three items are needed for a successful LS SWAP.
Lab Rats Peformance, LLC specializes in the design and manufacture of Standalone Wiring Harnesses for GM Gen II, III, and IV LS based engines and transmissions. These harnesses include the Gen II LT1/LT4, Gen III (24x) LS1/LS6 and Vortec Truck Engines as well as Gen IV (58x) LS2, LS3 and LS7 Engines. In addition to wiring harnesses, you will find other components and kits for retrofitting older vehicles with these powertrains including PCM programming, Fuel Pump Kits, Engine Sensors, Extension Harnesses, Replacement GM connector pigtails and a complete line of hardware to complete your conversion needs!