Piston Slap: Putting the Brakes on Auto Start/Stop?
Hagerty Community member HelenC writes:
Sajeev, my question is how do you disable the stop/start feature on a Jeep Grand Cherokee? It would be a tremendous service to your readers if you explained how to do it on not only Jeep products but GM and Ford.
I know the car companies have not come up with such an iterative feature since they put those seat belt starter interlocks on cars back in 1974. However it was easy to disable by just cutting all the wires under the seat. This aggravation may be more complicated to find which wires to cut so all your help would be appreciated.
Sajeev answers:
Turns out I got this one wrong, as there are modules that defeat this system. But remember these can void your vehicle’s warranty, so let the buyer beware.
Before I reply, please permit me to weasel out of a proper answer. Because getting a representative vehicle from all manufacturers, performing the task (either manually or electronically) to verify for myself, and then subsequently getting banned from all media fleets would kinda tank (what’s left of) my career as an automotive journalist. I’m only kinda joking, as doing this on not-media fleet vehicles would also be too cost prohibitive. And with that out of the way…
Let me instead point you in the right direction to disable auto start/stop in your vehicle. And this “pointing” is more valuable over time, as vehicle systems change over time, but the people who work on them generally do not.
- Call or email ECU tuners (Ford, GM, Chrysler) to see if they can remove auto start/stop from their software. This is often possible, but only they will know as they have access to the software and the ability to do what you want.
- Ask a dealership’s service department if start/stop can be removed either with their software, or unplugging/bypassing a wiring harness. (I assume the answer will be no, but it never hurts to ask.)
- Find out who makes the start/stop starter unit in your application. (Denso is a well known brand in this space.) Once you know the brand you can see what inputs it takes from the rest of the car to operate. Maybe you can disable start/stop without destroying the rest of the starter.
My advice tries to cover all bases, but honestly, you only need the first option. An ECU tuner will know more than anyone else, as modern cars use multiplex wiring that ensures any physical modification will take out more things than just the start/stop feature.
I suspect a tuner can make the system default to “off” so you can hit the button and turn it on if you tire of getting 0 MPG in traffic. Problem is, the tuner’s work isn’t free. It will cost hundreds of dollars, but it’s worth it if you also load a tune that allows for more power (premium fuel sometimes required), eliminate the throttle/torque management software, and firm up the transmission shifts.
Almost all of my EFI-powered vehicles have been tuned by a professional in the aftermarket, and I recommend it for more reasons than just disabling a start/stop feature. But that should get you exactly what you need, no matter what make or model we are discussing.
(For the record, I have no problem with this feature in late model vehicles. Times have changed, its operation is relatively seamless, and eliminating periods of 0 MPG when stuck in suburban sprawl has financial and ecological merit.)
Have a question you’d like answered on Piston Slap? Send your queries to pistonslap@hagerty.com—give us as much detail as possible so we can help! Keep in mind this is a weekly column, so if you need an expedited answer, please tell me in your email.
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I had a hybrid with it for over 100k miles. It was jarring for about a week then I stopped noticing it. It was by far better than watching the MPG drop while going zero inches per hour.
This is the first time I’ve read this series and I enjoyed it. I will read it some more and I’m sure I will have more comments.
Welcome! I think you’ll enjoy your time reading Piston Slap.
Start- stop engines are just about the stupidest thing manufacturers have ever invented. It puts excessive wear and rear on the starter and the engine. People thinks it will save them gas. It may do that, but they will have a higher maintenance bill. This is not creative engineering, it is idiocy!
When it’s a 100 degrees outside I want my AC if I’m at a busy intersection and I’m sitting for a few minutes.
Honda, Nissan all have that feature now. Auto stop, newer vehicles come with a push button to turn it off/on. Older models, it’s probably your car manuals. Chevy cruze early models to click the button on your gear shift to disable it.
In tha mazda there is a sensor beside the bonnet catch in the front grill, this sensor is ther to keep the motor running when the bonnet is up, just adjust this so it stays in the closed postion when bonnet is shut
I can’t believe automobile design has digressed to having all this computer crud do so many worthless things to the driveabilty of these over complicated cars. My collector cars NEVER cause a problem that is hard to fix at home and on a very rare instance, a problem that is hard to fix at the side of the road. It takes two things for a car to be good. Reliability AND repairability. New computer laden cars only have reliability.
Seems the as/s would be associated with the brake light switch/peddle. Press the peddle the engine shuts down. Release the peddle and the engine starts
I wish that Ford would fix the starter problems on the F150’s that when the starter gets hot from either towing or stop and go traffic causing it not to start until the truck cools off. I have had it happen to me in traffic and it’s not fun. They have no fix and don’t seem to care if they do. If the starter worked properly I wouldn’t have a problem with it.
2023 Traverse High Country. Turn on A/C set at any temperature turns off Start/Stop.
My 2024 Nissan Pathfinder has a button that defeats the auto start/stop by the shifter.
Installed an auto start/stop deactivation module in my 2023 Alfa Guilia QV that connects directly behind the auto start/stop button and defaults it to OFF. Relatively cheap, super easy to install mod, and it works perfectly. Now, if I could only default the loathsome auto-brake feature to OFF without having to go deep into the Driver Assistance settings menu every time I start the car, I would be a very happy camper.
Stop/start systems may save fuel, however, it’s at the cost of a starter that’s going to wear out faster than it otherwise would. I have seen no difference in the starter used in a car with/without, other than the gears are helical cut and the flexplate/flywheel is also (quieter).
There’s also bearing wear issues that are still being studied as the car has zero oil pressure on start for that brief moment as the engine is asked to operate at load vs just idle.
Additional complication in some cars with second batteries and their associated modules, relays and wiring, in some cars if that battery goes bad, you’re getting towed as when it tries to stop/start, it dies and won’t restart.
Many use electric boost pumps put in automatic transmissions to keep pressures up while the engine is off.
Because breathing all that polluted air when stuck in traffic is good for us.
My 2020 Ford Ranger has a disable button on the console, and doesn’t reset to auto start unless you disengage the overide button. On hot days in traffic, with the AC running, the auto start function does not engage .