It usually happens on the coldest morning of the year. You walk out, press the button, nothing. Press it again harder, as if that helps. Then you stand there in the parking lot at the Co op with a bag of groceries wondering whether the truck is broken or the little plastic thing in your hand is. Nine times out of ten it is the little plastic thing, it is a five dollar fix, and there is a backup procedure printed in your owner's manual that almost nobody knows about. Our parts department stocks the right batteries and will tell you which one your fob takes in about thirty seconds.
Here is the whole thing: which battery you actually need, how to change it without wrecking the case, and how to start the truck right now if you are stranded reading this on your phone.
Key Takeaways
- Start the truck with a dead fob by holding the nose of the fob, the end opposite the emergency key, flat against the ENGINE START/STOP button and pushing the button with it. The immobilizer chip inside is passive and does not need battery power.
- There is a mechanical key hidden in the fob. Slide the release and it pulls out. It unlocks the driver's door even when the fob is completely dead.
- The battery is not one size for everything. The current Ram 1500 proximity fob takes a CR2450. Ram heavy duty fobs of recent years take a CR2032. They are different sizes and are not interchangeable.
- If the little LED still flashes when you press a button, the battery is probably not your problem. Mopar's own instructions say not to replace the coin cell in that case, and you are likely chasing something else.
- Cold kills coin cells early. A battery that is fine in September can be too weak to reach the truck across a parking lot in January. If your range has been shrinking, replace it before winter rather than during it.
First, Which Battery Does It Take
This is where most people get it wrong, and it is why half the fobs that come to our counter arrive with the wrong battery already jammed in them.
The current Ram 1500 proximity fob takes a CR2450. That is the specification in the 2026 Ram 1500 owner's manual, and it covers the current generation of the truck. The CR2450 is the bigger, thicker coin cell.
Ram heavy duty fobs of recent years take a CR2032. The 2500 and 3500 owner's manuals from this era call for a single CR2032, which is the thinner, more common one that fits half the electronics in your house.
They are not interchangeable. A CR2450 is 24.5mm across and about twice the thickness of a CR2032. Forcing the wrong one in either does nothing or damages the contacts. The Jeep side follows a similar split, with the current Wrangler, Gladiator and Grand Cherokee proximity fobs on the larger cell and older or simpler fobs on the smaller one.
So the honest instruction is this. Open your own owner's manual and look, or open the fob and read the number stamped on the battery you take out, or bring the fob to our counter and we will look at it and hand you the right one. What you should not do is buy a multipack of CR2032 because that is what the drugstore had, then decide the fob is broken when it does not work.
Mopar recommends using a Mopar battery for proper fit. In practice, any reputable name brand cell in the correct size will work fine. What matters is the size and that it is fresh, since coin cells sitting in a bin for three years are not what you want going into a fob heading into a Manitoba winter.
How to Change It Without Breaking the Case
Mopar's procedure is straightforward, and the two places people break things are the prying step and the polarity.
- Pull the emergency key out first. There is a release on the fob body. Slide it and the metal key blade pulls free. Set it aside.
- Hold the fob with the buttons facing down and work a small flat screwdriver or, better, a plastic pry tool into the seam on the left side until the cover snaps loose.
- Move to the seam on the right side and pry that open too, then lift the back cover off.
- Slide the old battery out, downward and back toward the key ring, using a tool rather than digging at it.
- Put the new battery in with the plus sign facing up, tucked under the small lip on the top edge of the opening. Try not to touch the faces of the battery, because the oils off your fingers genuinely do shorten its life. If you do touch it, wipe it with rubbing alcohol.
- Line the cover back up and press the edges together until everything snaps with no gaps, then slide the emergency key back in until it locks.
That is it. No programming, no relearn procedure, no trip to the dealer. The fob keeps its pairing through a battery change.
One note worth repeating from the manual. If the LED on the fob still lights up when you press a button, do not replace the coin cell. A blinking LED means there is power in there, so a fob that will not lock or unlock the truck with a live battery is telling you something else is wrong. That could be the door module, the receiver, or the fob itself, and the fix is diagnosis rather than parts. Our service centre can chase it down properly.
The Dead Fob Start Nobody Knows About
This is the part worth remembering even if you never change a battery yourself, because it turns a tow truck call into a non event.
If the fob battery is flat and the truck will not recognize the key, take the fob and hold the nose of it, the end opposite where the emergency key comes out, flat against the ENGINE START/STOP button. Then push the button with the fob itself. The truck starts.
The reason it works is worth knowing. The chip that tells the truck this is the right key is a passive transponder. It has no power of its own and never did. It draws the tiny amount of energy it needs from the field around the start button when you hold it close enough. The battery in your fob is only there to run the remote buttons and the proximity sensing at a distance. So a completely dead battery does not lock you out of your own truck, it just shortens the range to zero.
To get in the door in the first place, use the emergency key blade hidden in the fob. It works the driver's door lock mechanically, no power required. Be ready for the alarm to sound when you open it that way, and it will stop once the truck recognizes the key on start.
Between those two things, a dead fob is an inconvenience and never a reason to be stranded. Worth showing your spouse or your kids once, in the driveway, on a nice day, rather than explaining it over the phone at minus 30.
The Manitoba Part
Coin cells lose voltage in the cold. That is not a Ram thing, it is chemistry, and it is why fob problems cluster in December and January instead of spreading evenly through the year.
What that looks like in practice is a fob that has been getting a little worse for months without you noticing. In the summer you could unlock from across the lot. By October you have to be a few steps away. By the first properly cold snap you are standing beside the door pressing the button and nothing is happening. The battery did not die that morning. It has been on the way out since spring, and the cold just finished it.
So the practical advice for anybody up here is to treat the fob battery as a seasonal item, not a wait until it fails item. If your range has noticeably shrunk, change it in the fall. It costs a few dollars and thirty seconds. Buy two and put the spare in the console, because the second one will cost you nothing to carry and it will eventually save you a morning.
A couple of related things people mix up with a dead fob. If your remote start has quit but the fob still locks and unlocks fine, that is usually not a battery problem, and our post on why Ram remote start stops working walks through the actual causes. And if the fob is working but the door will not open, you are probably dealing with ice rather than electronics, which we cover in frozen car door locks.
If the truck is throwing odd messages on the screen alongside the key problems, that can point at something else entirely, and Uconnect screen problems is the place to start there.
When to Just Bring It In
Change it yourself. It is genuinely a two minute job and there is no reason to pay anybody for it.
Bring it to us when the battery is new and the fob still will not work, when the LED does not light at all with a fresh cell in it, when the case is cracked or the buttons have gone mushy, or when you need a second fob programmed. That last one does require dealer equipment, and it is much cheaper and less stressful to do when you still have one working key than after you have lost it. If you are down to one fob for a truck you rely on, get a spare cut and programmed before something happens to it.
You can book service online, or just walk into the parts counter with the fob in your hand and we will sort it out while you wait. And if the truck attached to the fob is getting on in years, our new Ram 1500 lineup is on the lot whenever you want to look.
FAQs
What battery does a Ram key fob take?
The current Ram 1500 proximity fob takes a CR2450, per the 2026 Ram 1500 owner's manual. Recent Ram 2500 and 3500 fobs take a CR2032. They are different sizes and cannot be swapped for each other, so check your manual or the number on the battery you remove.
How do I start my Ram if the key fob battery is dead?
Hold the nose of the fob, the end opposite the emergency key, flat against the ENGINE START/STOP button and push the button with the fob. The immobilizer chip is passive and works without battery power.
Do I need to reprogram the fob after changing the battery?
No. The fob keeps its pairing through a battery change. Reprogramming is only needed when you add a new fob, and that requires dealer equipment.
My fob has a new battery and still does not work. What now?
If the LED lights when you press a button, there is power in the fob and the problem is elsewhere: the receiver, a door module, or the fob hardware. That needs diagnosis rather than another battery. Bring it in and we will test it.
Can I get into my truck if the fob is completely dead?
Yes. Slide the release on the fob and pull out the emergency key blade. It unlocks the driver's door mechanically. The alarm may sound until the truck recognizes the key when you start it.
The Bottom Line
A dead key fob is one of the smallest problems your truck can have, and it feels like one of the biggest the first time it happens in a cold parking lot. Two things fix that permanently. Know which battery your fob takes, and know that you can start the truck by holding the fob against the start button.
Do those and a flat coin cell becomes a minor annoyance instead of a phone call to a tow truck. Come see us at the parts counter if you want the right battery in your hand without guessing, and we will show you the start button trick while you are here.
Tyler Dunn, Dunn Ram Trucks, Portage la Prairie
