HOW TO INSTALL LML DSP5 SOTF

LML 11-16 6.6L SOTF DSP5

Tools You’ll Need

  • 7mm / 10mm socket

  • Trim tool or flathead screwdriver

  • Drill + step bit (only if mounting a new switch hole)

  • Flashlight

  • Zip ties

What DSP5 Does (Quick Explanation)

  • DSP5 allows 5 different engine tunes

  • Controlled by a 5-position rotary switch

  • Switch signal goes directly to the ECM

  • Requires DSP5-enabled tuning

DSP5 does nothing without proper tuning

Step-by-Step Installation

1. Disconnect Both Batteries

  • Disconnect both negative battery terminals

  • Prevents CELs and ECM damage

2. Locate the DSP5 Connector Under the Hood

On 2011–2016 LML Duramax, the DSP5 connector is:

  • On the driver-side firewall

  • Near the brake booster

  • Usually a gray 5-pin connector taped to the harness

https://knowledge.duramaxtuner.com/hs-fs/hubfs/LML%20Switch%20fig%203.2.png?name=LML+Switch+fig+3.2.png&width=590

3. Plug In the DSP5 Harness

  • Locate the factory DSP5 port

  • Plug the DSP5 harness directly into it

  • Ensure connector clicks and locks

Plug-and-play - Do not force it

4. Route the Switch Wiring Through the Firewall

  • Use an existing rubber grommet

    • Commonly behind the brake booster

  • Push the switch wiring through into the cab

  • Seal grommet if needed

https://www.plowsite.com/attachments/image006-jpg.32001/?auto=webp&fit=bounds&format=pjgp&height=1920&optimize=high&width=1920

5. Mount the DSP5 Switch Inside the Cab

Common mounting locations:

  • Lower dash panel

  • Kick panel

  • Center console

  • Factory blank switch panel

6. Secure All Wiring

  • Zip-tie wiring away from:

    • Exhaust

    • Steering shaft

    • Pedals

  • Avoid sharp edges

7. Reconnect Batteries

  • Reconnect both negative terminals

  • Tighten snug (don’t over-torque)

8. Verify Operation

  • Key ON (engine OFF)

  • Rotate switch through all 5 positions

  • Start engine and confirm:

    • No CEL

    • Normal idle

    • No warning messages

How to Use DSP5 (VERY IMPORTANT)

ONLY switch tunes at idle

  • Vehicle stopped

  • Foot off throttle

  • Let idle stabilize before switching

 Do NOT switch while driving
 Do NOT switch under load

(DSP5 is not designed for on-the-fly changes like newer SOTF systems)

Troubleshooting

Truck stuck in one tune

  • DSP5 not enabled in tuning

  • Connector not fully seated

Check Engine Light

  • Battery not disconnected during install

  • Bent pin in DSP5 connector

Truck runs rough

  • Switched tunes without idling

  • Wrong tune order

Final Notes

  • DSP5 controls ENGINE tuning only

  • Transmission tuning is separate

  • Leaving the switch installed permanently is normal