2007.5-2010 GMC Duramax LMM Gauges & Monitors

Digital monitors on the 2007.5-2010 Sierra HD LMM

GM gave the GMT900 Sierra HD a reasonably informative dash for its day. The Driver Information Center reports transmission temperature and the oil-change notification, and SLE and SLT clusters add a voltmeter and oil pressure. What it does not report is anything about the exhaust. The LMM was the first 6.6L Duramax to run a diesel oxidation catalyst and a diesel particulate filter, and the controller keeps that filter clean through active regeneration, commanding late post-injection to raise exhaust temperature on purpose. A truck doing that work behind a dash that never mentions it is a truck you are guessing about. Because the LMM talks OBD-II over CAN, a plug-in display like the Insight CTS3 is plug-and-play on 1996 and newer OBD-II trucks and pulls boost, rail pressure, load and transmission temperature straight off the bus onto one five-inch screen.

Towing is where the readings earn their keep

Every LMM pickup left the plant with the Allison 1000 six-speed. The gas 6.0L Sierras used the Hydra-Matic 6L90 and the two are not interchangeable, so there is no guessing about what is under your truck. The Allison's unhappy habit is a limp mode that locks the truck in third gear, and transmission temperature is one of the readings LMM owners put on a screen while towing. Boost belongs on the same screen, because the LMM's water-cooled Garrett GT3788VA turbo sets boost with moving vanes that can gum up with soot, and because leaking charge-air boots are a known complaint on these trucks. Rail pressure shows how the Bosch CP3 is keeping up, and on this engine the CP3 draws its own fuel from the tank and pressurizes it to 26,000 psi with no factory lift pump helping it along.

Monitors, and displays that also tune

Shoppers mix these up, so it is worth being plain. A monitor-only unit reads the bus and draws gauges. It never writes to the engine controller, and that is the whole point if your Sierra is staying stock. A tuner that happens to carry a screen, such as Edge's Evolution CTS3, will show a similar set of values, including exhaust gas temperature, boost, transmission temperature, load and fuel level with data logging and speedometer correction, but its real job is calibration, and calibration on a street-driven truck needs to be backed by a CARB Executive Order number. Figure out which job you are hiring for first. Gauges are the cheaper, simpler answer when what you want is to see the truck's numbers.

What we carry

Edge Products covers this page for the Sierra HD. The Insight CTS3 84130-3 is the monitor: an OBD-II display that needs no tune to do its job. The EAS EGT kit 98620 is Edge's daily driver and tow kit, which is how exhaust gas temperature gets onto the screen. The EAS pressure sensor 98607 reads 0-100 psi and gives you another pressure channel. The 28603 pillar display mount holds a CTS3 where you can actually read it, and its own fitment spans 2007.5-2014 6.6L Duramax trucks. More parts for this engine sit under Duramax.

Fitment notes

The model year that trips people up is 2007. A Sierra HD Classic from that year is the GMT800 body with the LBZ; the LMM arrived only in the new GMT900 HD body partway through the year, which is where the 2007.5 label comes from. Within those years, cab and box choice and 3500HD single or dual rear wheels do not change the OBD-II port, so the monitor is indifferent to all of it. Mounting hardware ships with Edge monitors and no LMM-specific mounting problem is documented, so pick the mount that suits your sightlines. Across the other end, 2011 brought the LML engine, a new boxed frame and the Sierra Denali HD trim, so engine-specific parts do not simply carry over. Verify by VIN with the fitment checker before you order.

Frequently asked questions

Is installing a monitor on my Sierra plug-in, or does it need sensors?

The display itself is plug-and-play through the OBD-II port, and everything the controllers broadcast, including boost, rail pressure, load and transmission temperature, needs nothing more than that. Exhaust gas temperature and extra pressure channels are the exception, since those need an added probe or sender. Mounting hardware comes with the monitor.

Where does the display go in a GMT900 Sierra HD?

Edge ships dash and pillar mounting hardware with its monitors and there is no documented LMM-specific mounting trouble, so this comes down to where you want to look. The 28603 pillar display mount puts a CTS3 up on the A-pillar in your line of sight, and it lists fitment across 2007.5-2014 6.6L Duramax trucks.

Which readings matter most when I am pulling a trailer?

Transmission temperature first, because the Allison 1000 is the only transmission behind the LMM and it is one of the readings owners watch while towing; its limp mode locks the truck in third gear. Exhaust gas temperature next, which takes a probe, and then boost to catch a charge-air leak or a sticking vane. Seeing a regeneration raise exhaust temperature while you are loaded is useful context too.

Will these parts work on my 2011 Sierra Denali HD?

Not as a rule. The Denali HD trim arrived for 2011 along with the LML engine, rated 397 hp and 765 lb-ft, which added urea injection and a Bosch CP4 pump, so engine-specific parts between 2010 and 2011 are not one list. Hardware can be the exception: the 28603 pillar mount lists 2007.5-2014 Duramax, and the Insight itself covers 1996 and newer OBD-II trucks. Check the fitment checker per item.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.