WIRING HARNESS

  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

transmission package.

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

easier.