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Nuisance Noises

Winning the squeak-and-rattle battle

Perhaps one of the most annoying problems you'll find in a vehicle is a nuisance noise. While not necessarily a hazard, that irksome rattle or squeak can drive you batty on even a short trip. Maybe you figure you can live with those auditory interruptions—just turn up the volume on your sound system and forget about it. Or, you can figure out how to track them down and eliminate them. If you have mischievous small children, or you purchased your vehicle used, you might be surprised at what you'll find behind the A/C vents.

Vent System

Since noises coming from underneath the dash are the closest in proximity, and therefore the most annoying, we'll focus on how to eliminate those. Under-dash noises, in the form of squeaks, rattles, clicks, pops, and buzzes, are often signs of trouble in their early stages. Left unattended, they could lead to more serious consequences, such as wiring harness abrasion, and subsequent circuit problems, under-lubrication and vibration-related component failure, or, at least, inefficient function of components. That proverbial "squeaky wheel" needs to get the "grease."

Which brings up an interesting point: On many passenger vehicles, some under-dash component lubrication is actually required periodically—a point often missed even by those who should know better. Let's first consider potential noisemakers, and then we will discuss how to isolate the offending component, and the proper technique to silence it.

Weak Links

All of the control pedals—'accelerator, brake, clutch, parking brake (if so equipped)—have linkage systems that periodically need cleaning and lubrication. This is also true of many control lever designs used with parking brake handles. Steering columns often have universal joints near the base of the floorboard, requiring some sort of a protective boot, which can be knocked out of alignment, causing noise.

Wiring harnesses are generally held in place by ties or clips, but these clips can weaken or break, and ties need to be tightened periodically. Relay units are often mounted or secured by clips, ties, bands, or screws, and those come loose or fail periodically. Screws, bolts, nuts, or clips often secure service covers and shields, and they, too, need periodic maintenance.

Let's not neglect the variety of aftermarket accessories that mount under the dash as well, such as alarm controls, trailer brake units, cruise control, and air conditioning units (less common these days), sound system components, etc. These units are often not mounted as securely as original equipment components, and can often be the source of under-dash noises, requiring more creative solutions to secure and immobilize them.

Feedback

As far as isolating noises involving the other components, it's pretty straightforward. If the noise occurs while using a component, such as one of the control pedals/levers, you'll need to remove the lower dash cover, if so equipped, and make a visual inspection of the linkage. If things look extremely dirty, where it may be necessary to disassemble the linkage, it might be a good idea to refer the work to your favorite service pro, safety being the main consideration here. If it's completely clean and seems to be well adjusted, and it appears that there are no permanently lubricated (plastic) sleeves used, try applying some long-bodied grease to the critical pivot points on the linkage. Work the pedal/lever a few times, and the grease will get worked in enough to stop the noise.

Fasten Up

If the noise occurs when you hit sharp bumps, you'll need to simulate such a bump, the palm of your hand being a good tool for this purpose. Be careful not to bump the dash too hard, or you'll have an extra expense to deal with (and perhaps some damage to your hand as well). Again, with the lower cover removed, you'll be able to isolate the offending component by systematically damping each component (relay, control unit, harness section, etc.) as you bump with the other hand. Make sure that you know the frequency, or pitch of the noise you are after, or the search can get confusing. And by all means, for safety's sake, only perform this procedure with the vehicle parked, on a level surface, with the engine off.

When you find the trouble area/component, determine if merely a tightening of existing fasteners will remedy the situation, or if new fasteners or ties will have to be added. Sometimes, industrial grade "hook-and-loop" fastening material may be a good medium to use, but your creativity and familiarity with your options and the existing circumstances are the best guides here. Experimentation is encouraged, along with forethought and common sense.

With a little practice, you can get really proficient at isolating and eliminating under-dash noises, not to mention the fact that being able to make effective repairs while working upside down in close quarters is an empowering experience. If you can do that, you can do anything!