1 relay for Ignition, and 1 relay to run your Fuel Pump. Depending on options, not all of the following wires will be included. The first three are the only ones needed to actually run the engine.
Battery 12V+ (mandatory) - ORANGE
This is a positive, full time, 12V+ source. It is separately fused. Avoid routing this connection through a “master” kill switch. The ECM goes through a learning process every time this connection is lost.
Ignition 12V+ (mandatory) - RED
Generally from the crank/run side of keyed source. It is separately fused.
Fuel Pump 12V+ (mandatory) - BLUE
This is the 12V+ from the fuel pump relay. The relay is controlled by the ECM and is
separately fused. When the ignition is turned on, the fuel pump will cycle approximately 3
seconds and turn off until cranking begins. Run directly to fuel pump.
MIL (Check Engine Light) 12V- (highly recommended) - BROWN/WHITE
This is a ground wire. Power the MIL with a keyed 12V+, then run this ground wire to the
other terminal of the light. This is a very useful tool in engine diagnosis. Mount it in a
location that you will immediately notice from the drivers seat.
OBDII Port / ALDL
This is the standard OBDII diagnostic port. It is used to “scan” the ECM for problems
if the MIL (Check Engine Light) comes on. It is also used for advanced engine tuning.
Starter Solenoid 12V+ PURPLE
This generally comes from the “crank” position of the key and what engages the starter to
actually crank the engine over for starting. 12ga. Wire recommended.
Tach output signal - WHITE
Most tachs can be calibrated to read this signal. See tach wiring diagram on last page for more info.
A/C Compressor 12V+ GREEN
I have been very successfully using this type of compressor to make compressed air. I add about an ounce of good synthetic Royal Purple gear oil every few runs.
Cooling Fan Control HIGH / LOW 12V-
This is a GROUND source from the ECM to control engine-cooling fans. It needs to
Be routed through an appropriate sized relay. Hook to negative side of relay coil. Use
The “low” if only one fan will be utilized. Low, on=202, off=195 High, on=210, off=203
VSS Signal - OUT - GREEN/WHITE
This is the signal coming out of the ECM to run a speedometer. The signal is calculated
from the “in” signal & based on tire diameter, & ring/pinion ratios. Most modern electronic speedometers can read this signal and be easily calibrated. Only available with transmission package.
4x4 Low Range 12V- GRAY/BLACK
This is a wire that needs to be grounded when in 4x4 Low Range. It tells the ECM to
recalibrate the VSS Signal for proper transmission control. Only available with
TCC Brake- (mandatory when using 4L60e or 4L80e Transmission) - PURPLE
TCC Brake Switch Signal is 12V+ when brakes are NOT pressed, and the switch OPENS
when you hit the brakes – it is used to unlock the torque converter when brakes are
pressed. Only available with transmission package.
OIL PRESSURE (only on DBC, 1999-2002) - LIGHT BLUE
This is the wire that comes from the factory Oil Pressure Sensor on the upper back of the
block. I like putting a sensor on the lower part of the motor as discussed above. But if
you want to use the factory one or put your sensor in this location this wire will make it