So my '07 E450 motorhome has this annoying habit on hills - cruise control kicks it down from overdrive to drive, then immediately drops to 3rd gear which is way too much. I just want it to stay put in Drive and stop being so jumpy.
I know newer trucks have those manual shift modes where you can lock a gear, but this old 5-speed auto doesn't have that luxury. Anyone know if there are aftermarket transmission controllers or mods that can hold it in Drive gear without all the hunting around? Would love to have more control over when it shifts.
Yes, there are aftermarket transmission controllers available for your 2007 E450 that can hold it in Drive gear. The most practical solutions include installing a manual shift valve body kit or an electronic transmission controller.
Nick, yes, there are several aftermarket solutions to hold your 2007 E450's transmission in Drive and prevent that annoying downshift to 3rd gear on hills. Your 5R110W transmission can be controlled with either a manual shift controller like the US Shift Quick series (around $400-600) or a transmission computer programmer like the SCT X4 with custom tuning ($600-800). The most popular and straightforward option for your Fleetwood motorhome is installing a gear command switch that essentially gives you the same M-mode functionality you have on your 2013 F150, allowing you to lock the transmission in Drive and prevent those unwanted downshifts to 3rd gear while maintaining cruise control operation.
Your 2007 E450 chassis came equipped with Ford's 5R110W TorqShift transmission, which is actually a pretty robust unit designed for heavy-duty applications like your Fleetwood motorhome. The transmission logic in these units is programmed quite conservatively from the factory, especially when it detects the additional load of a motorhome body. What's happening on your slight uphills is that the transmission control module (TCM) is reading various inputs - throttle position, engine load, vehicle speed, and grade - and making what it thinks are appropriate shift decisions.
The problem you're experiencing is extremely common among motorhome owners with this chassis. The transmission's programming prioritizes engine protection and fuel economy over driving convenience, so when it senses even a modest increase in load going uphill, it's quick to downshift to keep the engine in its power band. Unfortunately, the factory shift logic often overshoots, dropping two gears when one would have been sufficient. This creates that annoying cycling behavior where the transmission hunts between gears, never quite settling into the gear you actually need for the conditions.
The 5R110W has what Ford calls "grade logic" built into its programming, which is supposed to learn your driving patterns and anticipate gear changes based on throttle input and load conditions. However, this system was really designed more for pickup trucks towing trailers than for motorhomes with their constant heavy load and different aerodynamic characteristics. Your transmission sees the motorhome as a constantly varying load, which confuses the adaptive logic and leads to the excessive downshifting you're experiencing.
The reason your 2013 F150's manual mode works so well is that Ford had evolved their transmission control strategies significantly by then, plus that truck uses a completely different transmission (6R80) with more sophisticated programming. The M-mode on newer Fords essentially overrides the automatic shift logic within certain parameters, letting you hold gears as long as engine RPM stays within safe limits. Unfortunately, Ford didn't offer this feature on the 2007 E450 chassis, but aftermarket companies have developed several solutions to retrofit this capability.
For the most straightforward solution that mimics your F150's M-mode, you'll want to look at a manual transmission controller. The US Shift Quick 2 or Quick 4 systems are the most popular choices for motorhome applications. Check current pricing as costs vary, but expect to pay in the $450-650 range depending on features and supplier and adds features like automatic downshift protection and programmable shift points. Both systems require splicing into your transmission wiring harness, but they don't require any permanent modifications to your transmission or engine management system.
You'll also need some basic installation supplies: a quality electrical crimping tool, heat-shrink connectors, electrical tape, wire strippers, and possibly a small drill for mounting the control panel. The installation typically takes 6-10 hours including wiring, mounting, and system calibration, and requires experience with automotive electrical systems. Most systems include detailed wiring diagrams specific to the 5R110W transmission, and the wiring connections are made at the transmission itself rather than trying to access the main engine harness.
Another popular option is a transmission tuner like the SCT X4 Power Flash programmer, which typically runs $600-800 depending on where you buy it and what custom tuning files are included. This approach requires you to send your truck's computer file to a custom tuner who will modify the transmission shift points, shift firmness, and torque converter lockup strategy. Companies like 5 Star Tuning, Gearhead Automotive, and PHP (Power Hungry Performance) specialize in motorhome-specific tuning for the 6.8L V10/5R110W combination.
If you go the tuning route, you'll also want to consider upgrading your transmission cooler while you're at it. A larger auxiliary cooler like the Hayden 679 or B&M SuperCooler (around $200-300) will help manage the additional heat generated when you're holding the transmission in lower gears for extended periods. This is especially important for motorhome applications where you might be climbing long grades in Drive instead of allowing the overdrive shifts.
Let me walk you through the US Shift controller installation first, since it's the most straightforward solution for your specific need. Start by locating your transmission on the driver's side of the engine bay - you'll see a large connector going into the transmission case (refer to manufacturer specifications for exact pin count). This is your transmission control connector, and you'll be intercepting specific wires here rather than trying to access them under the dash or at the PCM.
The US Shift kit comes with a detailed wiring diagram showing exactly which wires to tap into for shift solenoid control. On your 5R110W, you'll typically be working with the shift solenoid circuits (consult manufacturer specifications for exact solenoid designations), plus the transmission range sensor wires. The beauty of this system is that it doesn't interfere with normal automatic operation - when the controller is off, your transmission behaves exactly as it did from the factory. When you activate manual mode, the controller takes over shift timing for the solenoids you've connected.
WARNING: Working with transmission electrical systems can affect vehicle safety and void warranties. Consider professional installation if unfamiliar with automotive electrical work. Installation involves carefully stripping small sections of the appropriate wires and connecting the controller's harness using the provided splice connectors. The most critical part is getting clean, reliable connections that won't corrode or come loose with engine vibration. I always recommend using marine-grade heat-shrink connectors and applying dielectric grease to protect against moisture. Once the wiring is complete, you'll mount the control panel somewhere convenient on your dash - many owners choose a spot near the gear selector or on the center console where it's easy to reach while driving.
After installation, you'll need to calibrate the system for your specific transmission. This involves driving the motorhome through various conditions while the controller learns your transmission's shift characteristics. The process typically takes 50-100 miles of varied driving, during which the controller maps your transmission's solenoid response times and pressure curves. Once calibrated, you'll have full manual control over gear selection, with the system preventing shifts that could damage your engine or transmission.
If you choose the tuning route instead, the process is quite different but potentially more elegant. You'll connect the SCT programmer to your truck's diagnostic port (located under the dash near your left knee) and download your current computer calibration. This file gets sent to your chosen tuning company along with your specific requirements for shift behavior and performance goals. The tuner creates a custom calibration file that you then upload back to your vehicle using the same programmer. along with details about your motorhome's weight, tire size, rear axle ratio, and driving preferences. The tuner will modify your transmission's shift schedules, typically raising the shift points, firming up shift feel, and adjusting torque converter lockup strategy to better suit motorhome applications.p the shifts slightly, and adjusting the grade logic to be less aggressive about downshifting.
Custom tuning can also address other issues you might not have noticed, like improving the torque converter lockup strategy for better fuel economy and reducing the annoying "shudder" that many motorhome owners experience during light acceleration. The tuner can also optimize the transmission's behavior for your specific application - motorhome tuning is quite different from pickup truck tuning because of the constant heavy load and different aerodynamic characteristics.
Whichever route you choose, I strongly recommend installing a transmission temperature gauge if you don't already have one. When you're manually holding gears or using custom tuning that allows more aggressive operation, it's important to monitor transmission fluid temperature. Normal operating temperature should stay below 200°F during regular driving, and you'll want to keep it under 220°F even during extended hill climbing. If temperatures consistently run higher than this, you'll need to add auxiliary cooling before using the manual override features extensively.
While both the manual controller and custom tuning options can be DIY projects, there are definitely situations where professional installation makes sense. If you're not comfortable working with automotive electrical systems, the wiring required for a shift controller can be intimidating. A mistake in the transmission control wiring could potentially cause expensive damage, and troubleshooting electrical issues in these systems requires specialized knowledge and equipment.
Most RV service centers and transmission shops are familiar with aftermarket controllers like the US Shift systems, and professional installation typically runs $300-500 in labor depending on your location. The shop will also have the proper tools to test the installation and ensure all connections are secure and properly protected. They can also integrate the controller installation with other modifications you might want, like adding a transmission temperature gauge or upgrading your cooling system.
For custom tuning, working with an experienced tuner who specializes in motorhome applications is absolutely crucial. Generic "performance" tunes designed for pickup trucks can actually make your shifting problems worse and may not account for the unique operating conditions of a motorhome. Companies like 5 Star Tuning have extensive experience with the E450 chassis and can provide tuning that addresses your specific shifting concerns while maintaining reliability and fuel economy.
The professional tuners also have access to more sophisticated calibration tools than what's available to consumers. They can modify not just shift points but also shift overlap timing, line pressure curves, and adaptive learning parameters. This level of customization typically isn't possible with off-the-shelf programming tools. A good motorhome-specific tune will cost $400-600 beyond the price of the programmer, but it's often worth it for the dramatic improvement in driveability.
If you're experiencing other transmission issues beyond the shifting complaints - things like harsh shifts, delayed engagement, or slipping - it's definitely worth having a transmission specialist evaluate the unit before installing any aftermarket controllers or tuning. Sometimes what feels like a shift logic problem is actually masking mechanical issues that need to be addressed first. A good shop can perform a comprehensive transmission evaluation and let you know if your 5R110W is a good candidate for aftermarket modifications or if it needs service first.
Help us improve this article by flagging technical issues or inaccuracies.
Was this guide helpful?
Try our free RV calculators and tools to help diagnose and plan your repairs.
Browse RV ToolsWeight calculator, electrical planner, propane estimator & more