Typical Duramax

Stand Alone Connections

Duramax LLY with Allison

Duramax LBZ with TH400

LB7 Duramax with Allison

Duramax LMM with Allison


For $541.00 your LB7 LLY LBZ or LMM Duramax Engine to Chassis harness is reworked and turned around in 2 weeks to have just three connections required to make the engine and transmission function as a Standalone: 12V Battery, 12V Ignition (Key On) and a Single Ground. (for Top Kick, Kodiak, Express and Savanna Van harnesses add $95.00) 

 When your donor harness arrives it will be checked in and you will be contacted by phone to build up the work order for your specific setup.  From that point the harness will be finished and ready to ship within 2 weeks.

Here's an example of our standard work order:

Convert customer supplied Duramax engine and transmission harness for standalone use as follows:

• Remove all factory convoluted (loom) tubing and tape.  Completely clean and degrease harness.

• Retain Allison TCM or setup for 4L80E, 4L85E, TH400, Powerglide, or Manual Transmission. (customer choice)

• Reconfigure harness for individual connector runs and a centralized ground.

• Install a Delphi Covered Fuse Block with ECM, FICM and TCM power relays as needed. 

• Check all terminals under magnification and electrically test power and ground circuits.

• Install OBD2/ALDL Connector - 5 Feet Long. (longer available on request up to 55 feet for dyno use)

• Identify Park Neutral Position connections and provide schematic for starter. (LB7 and LLY only)

• Identify Back Up Lamp connection on PNP switch and provide schematic. (LB7 and LLY only)

• Retain Duramax Alternator controlled by PCM.

• Retain or Remove Glow Plugs and EGR circuits.

• Identify Cruise Control pigtail connections at PCM and provide schematic. (LB7, LLY and LBZ only)

• Remove all Air Conditioning control related circuits. Return to customer for use with Vintage Air or other aftermarket AC.

• Remove Coolant Level indicator control circuit. Return to customer.

• Identify Wait to Start, TCC and MIL lamp pigtail connections at PCM.

• Identify Tach and Speedometer pigtail connections at the PCM. (LB7, LLY & LBZ only.)

* Every Duramax Harness is recovered with new GM Spec High Temp Loom and High Temp Harness Tape.

* Express Van and Savana harnesses can also be converted. (they will be significantly simplified especially the trans section)

​* Pricing is $541.00 for a Truck Engine to Chassis Harness and $636.00 for a Van Engine to Chassis Harness. 

ECM and TCM Tuning is also available.  For example a base standalone tune (aka Single Tune) is $350.00 or a www.DMaxswap.com EFI Live DSP5 standalone + performance tune with Switch is $550.00.  Contact DMaxswap.com for additional details.  Please do not ship any modules to us.  You need to retain your modules and work with the tuner directly.  


Below is a list of features that may have been in the donor truck that we do not offer to support.  Some of the features have a work around so feel free to contact us in the planning stage of your project and we can offer suggestions.


Unsupported Donor Vehicle Options or Features:

1.Tow-Haul or Tap Up/Down are not part of of a standalone harness as they require the BCM and/or specific  

   switched resistance values to work. 

2. Electric Shift Transfer Case function is handled by a different module so it is not part of a standalone harness.

3. Air Conditioning was controlled by the BCM which is not part of a standalone harness.

4. Donor vehicle gauges were controlled by the BCM which is not part of a standalone harness.

Since each setup is custom, contact Ken at (321) 604-1963 for a quote on your specific project requirements.