H3 Gas Pedal / Accelerator Pedal Squealing or Coil Whine Noises

[Burtor]

Hello,

I believe my gas pedal has a high pitched electronic squealing noise. It's nearly inaudible until you pick up on it, then your ears just tune right into it and you can't un-hear it. It reminds me of the issue that some graphics cards on PCs will have which they call "coil whine" noise.
It is similar to this https://youtu.be/HP73edpQwgc?t=1m40s

Has anyone come across this before? What else could I try checking before buying an entire new pedal assembly?

I'm completely unafraid of disassembling the unit and getting a soldering iron out to replace some components if that's a known fix.

Thanks!

Edit: I did try searching around for this first and came up empty, so if I just missed a previous discussion of this I'm sorry!

 

[JPaul]

I have never, ever heard of anything like this happening. What makes you think it's the pedal? All the pedal consists of is a lever (the pedal itself) hooked to two potentiometers which are resistive devices that should never emit an audible noise themselves (they typically don't resonate on their own unless they are part of an LCR circuit, and even then it's going to be the capacitor's or inductive coil that would audibly resonate rather than the resistors). There are no other electronic components in the pedal assembly. They hook directly to the PCM which reads their positions (it uses two potentiometers for accuracy and reliability). Also the voltage supplied to and from the pedal should be pure DC which is sampled using ADC's in the PCM. Pure DC won't cause anything to resonate either. It'd have to be pulsed DC in order for it to possibly resonate (and fairly high frequency to be in the audible range as it would need to cause the component to resonate such that it physically vibrates and emits audible frequencies. You can't actually "hear" electricity itself, just its effects).

If it increases as you press down on the pedal than it is likely something else causing it. Does it only do it while the engine is running? Or does it do it all the time? And have you determined where the noise is the loudest (thus indicating the possible source)?

If it's only while the engine is running, than it is probably an RF leak somewhere due to a failing or damaged component. Usually that will be either the alternator or something in the ignition. Possibly the electronic brake booster as well if it's only for a moment or so. It could also be the control modules emitting the noise, which if one of them is, then I would definitely suggest replacing it as that should not be happening at all.

If it does it even with the engine off, then something harder to trace down is having issues, but I'd be surprised if it did it with the engine off.


Has anything happened recently that might have caused the noise to occur? Such as getting a jump start, going through a large puddle, getting in an accident, getting struck by lightning, etc?

 

[Burtor]

[WRONG]It happens only when it's running[/WRONG], and I believed it is related to the pedal because changing the pedal position is what causes the frequency to squeal and shift to a different register. The frequency of whatever vibrating component is somewhere between 10,000 Hz and 14,000 Hz if I were to match it to one of those online frequency generators.

Something else in the ignition may be a good clue. One of the previous owners installed a remote start system, so I know that at least some parts aren't bone stock anymore.

I can also put an oscilloscope up to the voltage going in and out to see how stable it looks. Mentioning that the signal is supposed to be steady is another great tip.

No lightning or accidents or puddles or jumps that I know of. I just bought the vehicle from a private seller who didn't mention anything crazy happening.

I appreciate you taking the time to reply and provide some ideas.

I'll poke around and stick my head up under the dash to see what I can see, and listen to it more closely to zero in on the origin. I will report back as I get to the bottom of this!

Any other insights or suggestions will always be welcome, thanks!

EDIT: I was wrong, it will happen when the engine is off and ACC power is on. I'm going to find the remote start circuitry and try from that angle.

 

[4speedfunk]

Try putting some aluminum foil in your hat.

Just kidding. I have never heard of such an issue. Is it coming directly from the pedal?, or is it coming via the speakers?

 

[JPaul]

If they installed a remote start system, then that is the first place I would check. If you can I would try disconnecting it and see if that makes a difference. Odds are it will.

What you are probably hearing is alternator whine since from your description it sounds like the frequency of the whine you are hearing is changing with engine speed, but unless it's the alternator itself, it's probably something receiving interference from the alternator. If it was the fuel pump then it'd be a steady frequency and not change in pitch, the brake booster would be intermittent (when first started and when you press on the brakes), and the ignition coils would be popping sounds instead of a whine. You could possibly pick up RF from the CAN bus, but you'd have to have done something really poorly to get that, and it wouldn't change in pitch with the engine speed normally. It is unlikely you're hearing it from any of the OEM components.

Usually you don't get alternator whine in modern vehicles unless you're hearing it through a poorly installed CB or Ham radio (particularly CB radios due to the lower frequencies involved). But that will only come through the speaker of the radio (or in your broadcast signal).

The RF interference you seem to be experiencing is almost always attributed to a poor or missing ground or improper wiring, or a terribly shielded and filtered device. Which you shouldn't have that issue with any of the factory wiring or components. That aftermarket remote start kit though is very likely the source, especially if they didn't install it correctly. I'm not sure of all the problems they tend to cause, but I've seen a number of people that have had various issues with them in the H3's.

 

[Burtor]

I have made some discoveries

1) The squealing will still happen when the engine is turned off and the key is in the ON position. (I'm defining the key positions as are OFF - ACC - ON - *START*)
2) My usb phone charger amplifies the noise greatly.
3) Pulling the fuse for the radio, horn, or amplifier makes no difference.
4) In the on position I can hear the throttle actuating from under the hood.
5) If I disconnect the throttle actuator, the squeal will go away completely. (FIXED! ..but no car drivey-drivey)

As another note, if you connect your pedal while the system still has power, it will not detect it until you pull the key out for a minute.
You'll even get a bunch of error codes like *REDUCED POWER* and *TRACTION SYSTEM ERROR*

So, where can I check the ground points for the throttle actuator to be sure they are working properly?
At this point I believe there is cross-talk between the throttle actuator controls and the 12v outlets in the dash somehow.

I'll also figure out how to disconnect the remote start system to eliminate that possibility.

 

[alrock]

On a side note, I've seen some crappy USB 12V chargers that must have grounding issues and have caused noise in the electrical system. Doesn't sound like that's the primary issue here, but does sound like you might want to try a different phone charger.

 

[JPaul]

Start with the remote starter. Until you've eliminated that, you can't be sure it's actually an issue with the OEM components. And make sure you've unplugged anything else that isn't part of the factory setup, including your USB charger.