H&S MINI MAXX — INSTALLATION & FIRST DOWNLOAD

Head unit: seven buttons, five on the left and two on the right, a colour screen and a docking plug on the back. It is the last thing you plug in. Power cable: from the OBD II adapter to the fuse box, optional but recommended. OBD II adapter plug: the communication hub, with ports for the HDMI cable, the power wire and the optional pyro kit. Windshield mount: a suction cup mount. Mini USB cable and USB to micro SD adapter: for software updates from a computer. HDMI cable: the main line between the adapter and the head unit.

The T-shaped socket on the back of the head unit takes the top of the universal mount; slide it forward to lock. Stick the mount to the windshield somewhere that does not block your view of the road. Custom pod mounts are available if you prefer; follow the instructions with the pod.

The OBD II port is under the driver side dash. Plug the adapter straight in.

On the adapter: the OBD male end, the main harness port for the HDMI cable, the power wire port, the KEY/BATT power supply switch, a four-pin USB socket for the H&S pyro kit, a five-pin USB socket and the adapter fuse. If the port sits where the adapter could be kicked and broken, move the OBD II connection somewhere safer.

The OBD II port carries constant 12 V, so the Mini Maxx can run off it alone, but it then does not switch on and off with the ignition; you use the switch on the adapter instead. Powering it that way can also cause communication problems with the ECM.

The recommended way is the power wire to a keyed 12 V fuse, so the Mini Maxx is only on when the key is on and the ECM is awake. Set the adapter's switch to KEY.

Route the wire through the firewall to the fuse box. Pull the fuse listed for your truck in the next step and fit the fuse jack on the dead side of it, so the Mini Maxx stays protected by the fuse. Check with a voltmeter: fuse out, key on, engine off, the jack should read 0 V to ground. The wrong fuse either keeps the tuner on with the key off or powers it at the wrong point of the start cycle.

Strip 1/4" from the wire, crimp on the blue 90-degree connector, connect it to the fuse jack, refit the fuse and close the box.

Always tap the cold side of the fuse.

2006–2007 5.9L Cummins: fuse pictured.
2007.5–2009 6.7L Cummins: fuse 30, cold side towards the driver side.
2010 6.7L Cummins pickup and 2011 cab & chassis: fuse M45, cold side towards the front.
2011–2012 6.7L Cummins pickup: fuse M33, cold side towards the front.
2003–2007 6.0L Power Stroke: fuse 15, cold side towards the driver side.
2008–2010 6.4L Power Stroke: the solid purple capped wire under the driver side dash, bundled with other capped wires near the OBD II port.
2011–2013 6.7L Power Stroke: the white wire with blue stripe, capped, under the driver side dash near the emergency brake lever.
2007.5–2010 LMM Duramax: fuse 45, cold side towards the rear.
2011–2013 LML Duramax: fuse 45, cold side towards the front.

If your fuse box looks different or the source does not give 12 V with the key on, find another keyed source with a test light or multimeter, ideally one that stays live while cranking.

Plug one end into the main harness port on the OBD II adapter. Run the other end up through the driver side dash so it comes out near the A-pillar; pulling the weather strip and dash panel temporarily lets you hide it. Plug it into the back of the head unit, leaving enough slack to sit the unit on the mount.

Top left button: enter the Main Menu, and back out of any menu. The four buttons down the left select the item next to them and work as up and down. The two on the right change power level up and down, only from the main screen and only once a download is installed.

Press Menu and select Install Download, scrolling if needed. On a stock truck, follow the prompts; the tire size calibration and speed limiter menus appear along the way, and on some trucks the low boost fuelling, timing and torque management options.

When it asks whether the DPF is present or removed, select Removed if the emissions equipment is off the truck, otherwise the check engine light stays on.

The menu options: Download H&S Tuning installs the tuning. Import/Export MCC Tuning handles custom MCC files where available. Return to Stock (OEM Tune) puts the factory software back and unlocks the tuner; do this before service and before moving the tuner to another truck.

Four vehicle parameters down the left, a large gauge top right showing whichever one is highlighted with the black bar. Press a parameter's button to put it on the large gauge; hold it to change the graph style. The power level text shows Stock, Tow, Street or Hot once a download is installed.

Install Download. Gauge Set Up: choose which parameters fill the four gauge slots; highlighting one selects it. Set User Options: backlight, background colour, reset to default. Set Defuel Levels. Adjust Tire Size. Diagnostics: reads and erases trouble codes, engine or transmission where offered; the SD card must be in. Show Settings: vehicle, VIN, ECM and TCM part numbers, tune status and the tuning version. On Cummins and Power Stroke trucks the Part# and Transmission# shown here are needed for updates. Update Firmware. Performance Testing: 1/4 mile and 0–60 timers, which need an accurate speedometer.

Defaults: Pyro 1 1450°F, Pyro 2 off, engine coolant hot 210°F, cold start protection off, boost off, transmission temperature off, oil temperature off. In a parameter's menu, highlight a value to select it, use the Defuel On button to enable it and Defuel Off, bottom left, to turn it off. Which parameters appear depends on the truck.

Take the micro SD card out of the side of the head unit only for updates. Put it in the USB adapter, plug that into a computer, and follow the update instructions for your application in the downloads section at hsperformance.com. Have the Part# and Transmission# from Show Settings to hand.

The automatics learn adaptively, and the download resets that memory. A relearn gives it a baseline for the new power; it learns on its own over time regardless.

2008–2010 6.4L Power Stroke (5R110) and 2011–2013 6.7L Power Stroke (6R140): in the Performance power level, run 0 to 80 MPH at 25% throttle and stop, at 50% and stop, then at 100% and stop. Hesitation, hard shifts and defuelling during the runs are normal.

2007.5–2013 Duramax: key on, Main Menu, scroll to Reset Transmission and follow the prompts, then do the same three runs.

Follow posted speed limits and never do the runs in bad weather. With 3" or larger rear lift blocks, fit traction bars before adding power.

5.9L Cummins, 6.0L and 6.4L Power Stroke, LMM Duramax: the truck stays at the last power level. 2007.5–2012 6.7L Cummins and 2011–2013 6.7L Power Stroke: it drops back to Stock within a few drive cycles. 2011–2013 LML Duramax: power levels are not shift-on-the-fly, so unplugging changes nothing.

If the emissions equipment is coming off but the EGR stays in place, unplug it, or the engine runs erratically and loses power.

2007.5–2009 6.7L Cummins: unplug the light grey harness on the back of the EGR throttle control valve between the intercooler and intake, sliding its red lock tab sideways, and the brown connector on the EGR solenoid on top of the intake. 2010–2012 6.7L Cummins: not required. 2011 cab & chassis: also unplug the urea system.

2011–2013 6.7L Power Stroke: unplug the orange harness on top of the EGR cooler after sliding out its yellow lock tab, and the EGR butterfly valve near the fan shroud.

2011–2013 LML Duramax: unplug the three EGR harnesses, two brown with yellow lock tabs and one black with a red tab, and the urea injector between the cat and DPF plus the main urea harness above the urea tank. Leave the DPF pressure sensor plugged in; you may pull its two rubber lines but never its connector.

6.4L Power Stroke and LMM Duramax: the tuning already disables the EGR; nothing to unplug.