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SRT-4 Engine Management System: Wiring the Control Unit Computerized Engine-Control Module, Part 2 of 4 From "Tricked Out" episode DTRK-308

Once the ECM upgrade to this SRT-4 are complete, more efficient delivery of fuel/air mixture will result in a boost of more than 40 horsepower.

In this project, Andrew Totolos installs a computerized engine management system that will help custom match fuel and boost levels to the extensive mods already in place on a Dodge SRT-4. Now that the control modules have been mounted, it's time to get to work wiring the new control unit into the existing factory ECU. The boost control solenoid is also mounted.

Materials/Tools:

electrical supplies, including fuse taps and eyelet connectors
soldering kit
safety glasses
wire ties
electrical tape
scissors
split loom

Safety Alert: Always wear eye protection and ear protection, and follow proper safety precautions, when working with power tools or pneumatic tools. Also wear eye protection any time you are working underneath a vehicle.

Safety Alert: As a standard safety precaution, always disconnect the vehicle's negative battery cable before you begin work on any electrical or mechanical components.

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Figure A

Wiring Harness

• All cars are different, but in the project car, the ECU is located just under the air intake system under the hood.

• Accessing the ECU is simply a matter of unplugging the air temperature sensor, loosening the hose clamps and mounting brackets that hold the intake in place, and removing a couple of vacuum lines to release the assembly.

• Once you reach the ECU, unplug the orange and black plugs (figure A).

• Depending on your car, you might need to unplug an additional sensor or plug to release the harness enough to get them up to an area that you are able to work with them easiest.

• Next, peel back some of the tape and wire loom to gain access to the wiring.

• All cars will be different in regards to wiring coloring codes, but if you follow the instructions for the SRT-4 you'll have a pretty good idea what to expect when it comes to your car.
  

  	Figure B
  	Figure C

• Inside the black plug harness (figure B) there is a black wire with a tan stripe. This is the ECU ground wire (figure C). Strip it back, and wrap the black wire from the new system around it without breaking the circuit.

• Next, find the red wire with the white stripe. This is the ECU power lead, so use the same procedure to attach the red system power wire from under the dash.

• Inside the orange plug harness there is a black wire with a gray stripe. This is the tachometer line. The orange wire from the new system needs to be wrapped around it.

• Next, locate the white wire with the blue stripe. This is the injector output wire from the fuel injectors. Attach the purple wire from the new unit to provide a signal from this to the new control unit.
  

• The dark blue wire with the light green strip is the factory knock input, so attach the white knock sensor wire to it.
  

  Figure D

• The last wire for the orange plug is the dark green with the red stripe. This is the load input. It's the one that is intercepted, so it gets cut a few inches away from the plug. The green wire from the new unit is attached to the engine side of the wire, and the brown wire is attached to the plug side.

• When all of the wires are connected, solder all of the connections (figure D).

• Tape everything together securely, use wire loom to retain a factory appearance, and reattach the plugs.

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