Piston Slap: Cancelling Chrysler's Noise Cancellation?

by Sajeev Mehta

Updated: October 18th, 2019 Published: February 21st, 2017

piston slap cancelling chrysler s noise cancellation

Craig writes:

Hey Sanjeev, (*facepalm* –SM)

I have a 2015 Jeep Grand Cherokee SRT, and I’m bit of a music buff. One of the first things I dispensed with was the factory Harman Kardon speakers. I replaced the sub with a JL stealth box. Now I have a pretty big problem with the factory stereo and its the automatic noise cancellation.

When the transmission is in normal D mode and or eco mode is on, it uses the factory stereo to cancel out the drone of the engine. Unfortunately, the noise cancellation is calibrated for the weaksauce factory sub. Now it sounds like one of those bass CDs from the ’90s as I hold speed or decelerate. I’ve asked the dealer how to get rid of this thing, to which they said “you can’t.”

I’m not so convinced.

Any ideas?

Sajeev answers:

I totally get this. ~~Sanjeev is~~ I am a bit of an audio buff, too. Even my regular cab Ranger has small, 6-inch woofers in the back, aftermarket tweeters up front and a ghetto fabulous, 6-channel amplification system.

Chrysler’s noise cancellation certainly eliminates drones and rumbles, but engineers never consider owners upgrading to Audiophile grade hardware. That’s why I normally ditch all the factory stuff to go full aftermarket with a plug-and-play interface harness for a clean install, but Crutchfield says they have nothing for you.

And that’s bad news. Now you have two choices: acquire factory wiring diagrams or see if an aftermarket tune can delete it. Ask these guys if it’s doable. You might get a free performance tune in the process.

Regarding the diagrams, find where/how the audio system converses with your powertrain control module (PCM). I reckon it receives inputs regarding vehicle speed, throttle position or a similar input to determine engine load and provide noise cancellation. From there, in theory, you can cut some wires to defeat it.

Don’t laugh! It’s been done to re-instate digital clocks in Lincoln Continentals. Just make sure you solder/heat shrink/etc the wire(s) back to factory configuration if the hack fails to kill the noise cancellation or has unintended consequences like warning lights or error messages.

My take? Cut wires, be ready for the repercussions, possess a heat gun, soldering iron, and the necessary skills to return the wiring back to factory. If you don’t? Then don’t!

[Image: Shutterstock user MonsterDesign]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

#ActiveNoiseCancellation #Aftermarket #Audio #Audiophile #CarAudio #Chrysler #Factory #FactoryStereo #GrandCherokee #HarmonKardon #Jeep #Stereo #OEM #NoiseCancellation #JLAudio #Stealthbox #JLStealthbox #OEMStereo

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6 of 72 comments

S_a_p on Feb 26, 2017

Couple of things. First- Huge apology to Sajeev. This is quite embarrassing and I have no excuse for calling you Sanjeev. So I apologize profusely. Secondly, thank you for answering my question anyway and didn't think it was ECU related. I've thought about some other solutions mosconi dsp but it's 2k for that: http://mosconi-system.it/product/gladen-dsp-8to12-aerospace-2/ I've generally wanted to go with a stealth installation but I may change my mind on that as it currently only sounds good on about ⅓ of the music I play. The fine folks at Houston car stereo have told me that my car is a "challenge" to make sound good, which is unfortunate. A big chunk of my life is spent commuting the streets of Houston.

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- Sajeev Mehta on Feb 26, 2017
  
  Blame autocorrect, everyone else does. Good luck on your setup, email me on what you get in the end.
  
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DavidH on Apr 10, 2017

I have a 2015 Jeep Grand Cherokee SRT with the Harmon Kardon system. I just added a subwoofer and amp since I already had them from a previous car plus the bass was not very impressive from the 8" sub. I too have the same issue with the ANC. The one thing I noticed though is that the manual says ANC is only on in ECO/Auto mode. However I get the humming sound when I'm just in Auto mode only. Has this been the case with everyone else?

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- S_a_p on Apr 11, 2017
  
  Here's what I have found. If I leave it in Auto the Eco mode is activated automatically which causes the droning. If it is in sport mode it never goes to eco and only drones when the computer gets confused. What I mean is that there is a bug in the software that occasionally causes a slightly higher pitch drone that is independent of the sport setting. The only "fix" I have found for when this happens is to turn the car off and back on. As for the eco mode drone, I resorted to a low tech fix. My Rockford Fosgate amp has an option for a remote level control which I simply turn down when I'm not listening to music. If I want to rock out and jam I leave the car in sport or track mode. The main penalty is mileage has dropped from ~15mpg in mostly city driving to around 12.5mpg. I think the next step for me is to see if I can escalate this through FCA support if such a thing exists.
  
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- DavidH on Apr 25, 2017
  
  @s_a_p Thank you s_a_p for the response. It looks like what you're doing is be the best option. In my case I plan to install a switch to the remote wire to shut off the Pioneer amp that powers the aftermarket sub when I'm not cranking up the music. Fortunately, the way the line converter is installed, the original HK 8" subwoofer is still active, so I still get decent bass, albeit not the equivalent to the aftermarket 12"sub. I've been to the dealership to see if they had any idea how to disable or disconnect ANC, but they had no solution. One stereo installation place I went to said they turned away a couple of systems that had ANC because of the feedback issue that they didn't want to get involved in. On a related note, and probably for another post, but is it just me or does it seem like the 19 speaker HK system requires you to crank it to at least around 30 of 38 before it seems somewhat loud and to get decent bass? It sounds great, but just not much volume. The Rockfort Fosgate that came in my Nissan as an upgrade sounded much louder and more powerful.
  
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- S_a_p on Apr 26, 2017
  
  @DavidH I find the HK stereo very frustrating. The main issue is the WAAAAAY Over boasted low frequencies. On all 4 door speakers the low end causes my focals to bottom out, and they are good for 70w rms. This causes the overall volume to be pretty low unless the source material was mastered in a "Loudness War" style. For instance, Led Zepplin IV hardly gets loud enough to warrant raising my voice while having a conversation with a passenger even on 38, but if I play something like Run The Jewels I can probably hit 130db at least with the bass. I have been trying to tell myself it is fine and stop messing with it. Upgrading the speakers helped the sound quality quite a bit, but it kind of emphasizes the fact that the OEM radio/amp sucks. If I end up getting overly frustrated, I will probably rip out the stereo run all new wires and consider different speaker arrangements and a DSP preamp to fix the EQing/time delay. sigh...
  
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