Holley DBW Harness Throttle Body Plug Conversion

Things like this has happened to us all. We buy certain parts with our initial build plan, then decide to go a different route.  A very common issue with LS swaps using the Holley Terminator X ecu is the plug on the Drive by Wire harness that connects to the throttle body.  Depending on the year, model, style, etc you need either a 8 pin or 6 pin.  The most common issue is having an 8 pin harness and deciding to go with LS3 throttle body which requires a 6 pin connector.

Luckily, it can be easily changed without needing a new harness. We offer plug kits with optional been removal tool (a must if you do not have one) to simply change it to your needs.

Below are the wiring diagrams depending on which harness you have.

Holley 558-406:

Holley 558-406


Holley 558-429:

Holley 558-429


Both use very similar wiring.  The main difference is the addition of two power related pins on 558-429.

The main part we need to focus on is the following two diagrams.

558-406 TB Connector Details
558-429 TB Connector Details
As seen in the diagrams the only difference between the two is sensor ground and power being split out on an additional two pins.  So, if you need to go to a 6 pin from an 8 pin, you simply leave these two disconnected (tape or heat shrink them for protection) from the new plug.  
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