Ram Vehicle Systems
Ram 1500 TPMS Sensors, Hemi MDS, and Start-Stop: The Three Systems a Ram Owner Actually Deals With
A Ram is a simpler vehicle than it looks from the outside. It doesn't have cylinder deactivation on its V6, and it doesn't have the layered camera systems a newer crossover carries. What it has is a tire pressure system that generates most of the questions, a cylinder deactivation system in the 5.7 Hemi that most owners can't name, and — on the current trucks — an auto start-stop that doesn't come with an A-OFF button. Only one of the three is something we can help with.
01 — What A Ram Carries
Tire Monitoring, Hemi Multi-Displacement, and Start-Stop on the Current Truck
Three systems, three different failure stories, and only one of them has a product in our catalog. Sorting them at the start is what keeps a tire question from turning into an exhaust argument.
TPMS, and the button hunt
A sensor on each wheel, an identifier the vehicle has to learn, and a relearn that owners start by looking for a physical button. On most Ram 1500s that button is on the lower dash to the left of the steering wheel; on the heavy-duty trucks the relearn is driven from the instrument cluster instead. That single difference is behind most of the "where is the reset button" traffic on this brand.
MDS on the 5.7 Hemi
Chrysler's Multi-Displacement System rests four cylinders at steady throttle, using the same oil-pressurized collapsing lifters GM adopted. It arrives in the 5.7 Hemi and it is the reason a Hemi can tick at idle — and the reason delete kits from Melling, Texas Speed and Range Tech come up on a Ram at all. We don't sell those kits, and the reason matters.
Start-stop on the newest trucks
The current Ram 1500 shuts the engine down at lights and in queues. There's no user-facing switch to hold the setting between drives, which is the gap the harnesses in the band below close. Coverage is split by drive type, because the hardware differs between the two-wheel-drive and four-wheel-drive trucks.
02 — Sensors And The Button
Ram TPMS Sensors and the Reset Button, Model Year by Model Year
Most Ram tire pressure questions are really one question: where do I press something. The answer changed across the range, and a truck that has no button is not missing one. The Ram TPMS reset button location is the whole question, and on a 2019-and-newer truck the answer has moved into the screen.
| Model and years | Where the relearn is started | What to know about the sensors |
|---|---|---|
| Ram 1500, mid-2000s to 2018 | The TPMS button on the lower dash, to the left of the steering wheel | Hold the button until the cluster shows the relearn prompt, then drive. The system locates the sensors itself; the button only starts the process. |
| 2011 and 2013 Ram 1500 TPMS reset button | Same lower-dash button, same place as every other 1500 in the range | The 2011 Ram 1500 TPMS reset button and the 2013 one are identical — same button, same place. A 2011 Ram 1500 TPMS reset button location and a 2013 Ram 1500 TPMS reset button location haven't moved between them. |
| 2019 Ram 1500 TPMS sensors and later | The instrument cluster menu, on newer vehicles | A newer sensor generation that must be written to the vehicle by a scan tool after replacement. The keyless routine alone is not enough on a new sensor. |
| 2018 Ram 2500 TPMS reset button and 3500 | The instrument cluster tire pressure menu, not a dash button | Owners hunting the lower dash for a button on a heavy-duty Ram usually find the same function a screen away. There is no 2018 Ram 2500 TPMS reset button location to find, because the relearn is a menu item rather than a physical switch — the most common "there's no button" complaint on the brand. |
| Bed-mount spare | Not applicable | On most Rams the spare carries no sensor and is not monitored, so the system reports four positions. Confirm in the placard section of the owner manual for your year. |
The TPMS sensor for a Ram 1500 is a sealed module on the valve stem, same as any other direct-monitor truck, and a Dodge Ram TPMS sensor is not a different part from the ones on a sibling model. What is different is the relearn.
The general system — how the sensors are built, what the alert threshold is, and why a sealed battery matters — is in our TPMS guide. We don't stock Ram tire sensors or emulators, so for a genuine sensor replacement the right source is a specialist or a dealer rather than a guess.
03 — Ram Start-Stop Units
Ram 1500 Auto Start-Stop Eliminators: Two-Wheel Drive, Four-Wheel Drive and the Gateway Harness
Three units, listed by drive type because that's what actually decides the part. Confirm the year range on the product page before ordering — this hardware is specific to the current truck generation.
2025–2026 Ram 1500 · 2WD
Auto Start-Stop Eliminator
$99.99
Plug & play · two-wheel drive hardware
2025–2026 Ram 1500 · 4WD
Auto Start-Stop Eliminator
$109.99
Plug & play · four-wheel drive hardware
Ram 1500 · Gateway Harness
Auto Start-Stop Memory Harness
$79.99
Gateway interface · holds the off state
On what changes after installation: the engine no longer shuts down at lights or in queues, the off state is held rather than reset at every ignition, and nothing on the truck is reflashed — unplugging the unit returns it to stock exactly. The rest of the start-stop catalog covers the Chevrolet, GMC, Ford, Honda and Toyota applications if you're comparing across brands.
04 — Hemi MDS
MDS on the 5.7 Hemi: What It Is, What a Delete Kit Does, and Why We Don't Sell One
An MDS question on a Ram almost always means one of two things: a rattle at idle that the owner hasn't connected to a system, or a delete kit name from an aftermarket brand. Both deserve a straight answer, and neither one is a product we stock.
Four cylinders at rest
Multi-Displacement System rests cylinders 1, 4, 6 and 7 at steady throttle, running the 5.7 Hemi as a four-cylinder. It uses the same oil-pressurized collapsing lifters GM's AFM uses, which is why the wear story is the same story: a tick at idle that fades with revs is the lifters telling you something, and it will get worse rather than better.
Blocking the oil, not unplugging something
Three names come up for the same part, and all three are the same idea. A 5.7 Hemi MDS solenoid delete kit — sold as the Melling MDS delete kit, the Texas Speed MDS delete kit, or a Range Technology MDS disabler — blocks the solenoid feeds that pressurize the deactivation lifters. On a 5.7 Hemi that is engine work: it's permanent, and it's usually done with the engine apart. It is a different category of job from a plug-in module, and no plug-in part replaces it.
A tuner, where the engine supports it
On applications that support it, a tuner can change what the calibration allows, which switches deactivation off without touching hardware. It's not reversible by unplugging, and support varies by year and vehicle. This is the trade-off set out in full in Disabler vs Delete vs Tune.
05 — Resets And Codes
Hemi Throttle Relearn, ParkSense, and the Codes a Ram Actually Sets
The rest of Ram traffic is short procedures and network codes. Both are worth having in one place, because the procedures are free and the codes are a starting point rather than a verdict.
| Task or code | What it is | What to do |
|---|---|---|
| 5.7 Hemi throttle body relearn | Idle adaptation after a throttle body, throttle position sensor or injector service | Key on with the engine off, take up firm limited travel on the pedal and hold so the closed-throttle position is learned, release, start, let the idle settle, then drive through a range of throttle conditions. Skip the drive and it often looks like it failed. |
| A Ram ParkSense reset on a 1500 | The parking sensor system reporting a sensor or an obstructed area | Clean the bumper sensors, clear anything hanging off the tow hook or hitch, and cycle the ignition. A message that returns is a sensor fault rather than dirt. |
| A Dodge Ram odometer reset | A trip meter you want back to zero, or an odometer readout after a battery disconnect | Short procedure on the cluster, and it's worth knowing before a battery change so the mileage doesn't look interrupted to the next owner. |
| A U0100 code on a Dodge or Ram | Lost communication with a powertrain or chassis module | Battery state, grounds, and the module's own power feed before anything else. A network code describes a conversation that stopped, not the part that stopped it. |
| A U1110 code on a Ram 1500, U0001, U110E and similar | Other network codes in the same family | Read the definition for your year — these numbers move between model years — and treat them as a pointer to a bus, a module or its wiring rather than a failed component. |
06 — Questions Ram Owners Ask
Ram TPMS, Hemi MDS and Start-Stop: Straight Answers
Where is the TPMS reset button on a Ram 1500?
On most Ram 1500s in the 2009–2018 range, it's the tire pressure button on the lower dash to the left of the steering wheel. Hold it until the cluster shows the relearn prompt, then drive properly. On the heavy-duty 2500 and 3500 from 2018 onward, the relearn is started from the instrument cluster's tire pressure menu instead — so if you're hunting the dash for a button on a heavy-duty Ram, there isn't one, and the function is a screen away.
Do I need a TPMS relearn tool for a Ram 1500?
For a relearn on the truck's own sensors, no — the dash button and a proper drive are enough. After replacing a sensor on a 2019-and-newer Ram 1500, yes: those sensors have to be written to the vehicle by a scan tool, and the button routine won't do it. That's the difference between a free procedure and a tool, and it's worth knowing before you pay for anything.
Does the Ram 1500 monitor the spare tire?
On most Rams, no. The spare is a bed-mount or under-floor unit without a sensor in it, so the system reports four road wheels. Confirm for your year in the placard section of the owner manual, in the same door jamb as the cold tire pressures.
What is MDS on a 5.7 Hemi?
Chrysler's Multi-Displacement System, fitted to the 5.7 Hemi and using the same oil-pressurized collapsing lifters GM's AFM uses. At steady throttle it rests cylinders 1, 4, 6 and 7 and runs the engine as a four-cylinder. The practical consequence is the one GM owners already know: a tick at idle that fades with revs, and lifters that won't recover from it on their own.
What does an MDS delete kit do, and do you sell one?
A delete kit — the kind from Melling, Texas Speed or Range Technology — stops deactivation mechanically by blocking or removing the solenoid feeds that pressurize the lifters. It's engine work, it's permanent, and it's normally done with the engine apart. We don't sell those kits and we don't pretend otherwise. A tuner is the reversible-ish alternative on applications that support it.
My Hemi ticks at idle but is quiet driving. What is it?
On an MDS engine, that pattern is the deactivation lifters and it's the reason the delete kits exist. It's a mechanical condition that doesn't improve with miles, and it can end as misfires and heavy oil consumption. Have it looked at properly before ordering anything — a tuner or a delete addresses prevention, not metal that's already involved. The diagnose before buying guide covers the checks worth doing first.
Does the current Ram 1500 have an A-OFF button?
No — the newest trucks shut the engine down at lights and in queues with no user-facing switch to hold the setting between drives, which is the gap the harnesses above close. They interface with the vehicle's existing circuit, hold the off state, and come straight out if you want the stock behavior back.
How do I relearn the throttle body on a 5.7 Hemi?
Ignition on, engine off. Take up firm limited travel on the accelerator and hold it so the closed-throttle position is learned, release it, start the engine, let the idle settle without touching anything, then drive through a range of throttle conditions including a steady highway hold. It costs nothing and it resolves a surprising share of the "my Hemi idles rough" complaints that get blamed on something else.
Do you sell Ram TPMS sensors or emulators?
No. The start-stop units in the band above are the Ram products we carry, and for tire sensors we'd rather point you at the TPMS guide and the free reset procedure than at a part we don't stock. Most Ram tire messages are pressures, relearns or a single dead corner — and the first two cost nothing.
07 — Related Reading