Interior noise when shifting between PRND

838 Views 14 Replies 3 Participants Last post by AMENCADDY, Mar 29, 2009

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Discussion Starter · Mar 28, 2009

Since I bought my 93 Deville it has always made a noise that sounds like air escaping. The noise changes in pitch/tone when I use the column constant shifter to shift between park, neutral, etc. The noise is loudest when I hold it in between any two gears. It sounds like a vacuum leak, but I don't know which vacuum would be leaking. The only light on is ABS, Could it be the ABS that is loosing vacuum? The transmission shifts fine and the noise doesn't sound "metallic" so I dont think its the transmission itself. My other 93 does not have this issue either so I don't think its normal. Any tips?

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AMENCADDY

· #2 · Mar 28, 2009 (Edited)

If just the ABS is on and not both the ABS and RED brake light, then you have still got power brakes but your ABS system is either partially or totally inhibited. Do you get any DTC codes showing on your OBD?

As for the vaccuum problem, the parking brake lever has a vacuum controlled actuator. the hose is routed through the steering column area to the PB lever and may have come disconnected from the actuator. You'd have to remove the lower insulator panels of the dash to get at it. BE SURE to disable the SIR before you mess around with the dash, by A) removing fuse #18 AIR BAG fuse of your IP fuse box. B) After you remove that left insulator panel, Disconnect the yellow 2-way connector ( (with the lock-pin thru it) at the base of the steering column. Then you're safe to nose around under there for the vacuum line.

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Discussion Starter · #3 · Mar 28, 2009 (Edited)

No codes, The red light has come on a few times, but the master cylinder was low on fluid at the time, topping it off killed the red light, the abs light never goes out though. Do you think the abs pump could be the noise I am hearing?

EDIT: Just realized a typo in my first post. Basically the "air escaping" noise is constant whenever the engine is on, It get louder as I am shifting gears, once I select a gear it goes back to the way it was. The brakes are OK and I am not too concerned with the ABS light right now, just trying to pinpoint what I think may be a vacuum leak.

AMENCADDY

· #4 · Mar 28, 2009

You said it sounds like air when you shift right? the pump only works when you apply the brakes. but I'll be right back with some Dignostic instructions to pin poin the problem in my FSM.

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Discussion Starter · #5 · Mar 28, 2009

Heh, we edited at the same time. So you think it could be the parking brake vacuum? I never use the PB so I don't know exactly how it is supposed to work or if it is working properly, But I can pull the 18 fuse to disable the airbag and take a peak around their, Hopefully it will become obvious once I get it apart.

AMENCADDY

· #6 · Mar 28, 2009

LOL! first suggestion is to check fluid level, since you do that for the Red light. the only other reservoir is in the PM itself, so make sure that is topped up. Also, check fuse #8 in your ip fuse box. Then the 2 relays in your under hood banks may be causing problems. Does the car seem to brake normally or not?

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Discussion Starter · #7 · Mar 28, 2009

Car brakes alright, not the greatest, but not too bad. Think it may be due for a new master cylinder soon though. I had swapped the 2 relays in the hood at one time trying to get rid of the abs light but it didn't help. I will check fuse 8 in a few minutes. I went and tried to record the sound I am getting but the mic didn't pic it up well enough. I think you may be onto something with the brake though. I have to apply the brake to shift into drive or reverse so they probably are the cause of the noise, It does go away once I am in gear and have released the brake so I think that should narrow it down to something in the brakes (master cylinder) or parking brake vacuum.

I think my master cylinder may be on the outs, I had researched a few weeks ago on how to tell it is failing and mine shows some symptoms, For instance when I have come to a stop and have the brake pressed, after a while I can push it down a bit further. Guess I will keep an eye on that and look around in the dash to see if thier is a vacuum leak

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AMENCADDY

· #8 · Mar 28, 2009

I always leave this for last! Do you have a VOM? There's a whole bunch of Voltage checks in the diagnostic tree. If you want to do the tests, I can send the info.

AMENCADDY

· #9 · Mar 28, 2009

behind-bars said:
Car brakes alright, not the greatest, but not too bad. Think it may be due for a new master cylinder soon though. I had swapped the 2 relays in the hood at one time trying to get rid of the abs light but it didn't help. I will check fuse 8 in a few minutes. I went and tried to record the sound I am getting but the mic didn't pic it up well enough. I think you may be onto something with the brake though. I have to apply the brake to shift into drive or reverse so they probably are the cause of the noise, It does go away once I am in gear and have released the brake so I think that should narrow it down to something in the brakes (master cylinder) or parking brake vacuum.

I think my master cylinder may be on the outs, I had researched a few weeks ago on how to tell it is failing and mine shows some symptoms, For instance when I have come to a stop and have the brake pressed, after a while I can push it down a bit further. Guess I will keep an eye on that and look around in the dash to see if thier is a vacuum leak

What's your mileage? have you ever checked the linings on the Front pads? or the Rear. If it's losing brake fluid all the time, maybe your ride just needs new shoes., wheel cylinders or calipers may be too worn for comfort and safety.

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Discussion Starter · #10 · Mar 29, 2009

Ok... I pulled the brake fuse and it was fine, Brake fluid was full so I took the insulator panel off and took a quick look, Nothing that just jumped out at me. When I push the brake pedal by hand it makes alot of noise, a "whoosh" sound. I recorded it here
http://www.geocities.com/aebcoat/noise.mp3

The above site doesn't have alot of bandwidth, but it should work awhile.

I guess I will have to take a closer look at why the brake pedal is making that noise.

I think my parents have a meter, but it would be awhile before I could run any test using it. After hearing how the brake pedal sounds I dont think its a electrical issue though.

Thanks for the help so far.

Ranger

· #11 · Mar 29, 2009

Locate the vacuum line on the parking brake release diaphragm. First be sure that the line is attached. If so, check the diaphragm to see if it will hold vacuum. My guess is that's where the leak is. Does the brake release when you put it in gear?

AMENCADDY

· #12 · Mar 29, 2009

What a lovely whooshing sound (jk

). Okay, the brake pedal as you probly already know is connected to the thigh bone, err, i mean the brake booster pushrod. so 3 guesses where that noise is coming from. Right, not good news - the brake booster -only several hundred $$ for a rebuilt one at Rock Auto. Maybe get a used one at the junk yard? But then it might be in worse shape. Anyway, aside from checking the outside vacuum hose route from the booster to the pump motor and making sure the wiring harness is solid (especially the GND on the PMV assy - mystery solved.

On a happy note, let me just add that I've been driving my 84 Lincoln TC for 5 years now with 2 rear leaking wheel cylinders and a whooshing noise when I hit the brake pedal plus a constant vacuum hiss that changes pitch when I shift gears and the car brakes marvelously for me whenever I need it to - even if I have to slam on the brakes. Just keep adding that Dot 3 after every trip.:yup:

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Discussion Starter · #13 · Mar 29, 2009

AMENCADDY said:
What's your mileage? have you ever checked the linings on the Front pads? or the Rear. If it's losing brake fluid all the time, maybe your ride just needs new shoes., wheel cylinders or calipers may be too worn for comfort and safety.

Mileage is 119k. I have replaced the front pads within the last year, Fluid is needed once every 3 or 4 months so if its leaking its not real fast. Haven't touched the rear brakes at all.

I will dig deeper tomorrow and see if I can find a vacuum leak under the dash.

I'll keep everyone updated

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Discussion Starter · #14 · Mar 29, 2009

Parking brake works fine, I tried it today and it disengages when you go into either reverse or drive. The vacuum line is hooked into the parking brake, didnt test it for vacuum though. After playing around under their and under the hood the noise while shifting has become quieter, The brake pedal is still noisy but I am not to worried about that too much since the brakes work fine and it looks like it could get expensive trying to fix it. I will just keep an eye on it. As amencaddy said and what I have seen on other forums cars can last along time with the whooshing sound.

While looking under the hood I found something I didn't want to see. Looks like some critters got under their chewed a few wires. The wire loom over the 3 wires running into the drivers side strut tower has been chewed thru and the wires inside it are pretty bad, one of them is almost chewed all the way thru and the others are missing insulation. I unplugged the connector from the strut tower and it did not set any codes or lights which I thought was odd. Oh well, guess I will tape the wires up in the mean time until I can splice a new wire into it.

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AMENCADDY

· #15 · Mar 29, 2009

Wouldn't it be nice to be real wealthy so any repairs would not be a problem?. I drive knowing I got iffy brakes on the Lincoln but no $$$$ to have a brake job. Sigh! Dot 3 fluid to the rescue (and electrical tape too, in your case)

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