1987 Mercury Grand Marquis Electrical Problems

[emorabbit]

I've done a bit of work to this beast. Most of it has been brakes and suspension. Now i have an entirely new breed of problem. This time, its electrical.

The factory stereo was making a lot of noise, and was just really unpleasant to listen to. So I bought a new stereo. We hooked it up, and it sounded mediocre. So I bought new speakers. After installing them, the radio sounded great. The only problem is, When i hit a bump, or i am going over 45 miles an hour, the radio tends to sound like a ground wire is losing contact with whatever its grounded to. (Lots of hissing and loud noises)

At first, I suspected this to be a fuse that had broken, but was still making weak contact, so I checked the fuse box. All the fuses look good. I don't have a wiring diagram because the original owner file 13'd the manual (...).

I also have a second electrical problem, The power windows will roll down (except the back two, but that's a motor problem for sure.) The only way to roll down the front two is from the master panel on the drivers side. I was wondering if anyone knew of a second fuse box on a 1987 Mercury Grand Marquis?

Thanks in advance, Nick.

[crown vic muscle]

i would check all of your grounds on the radio and if it has the premium sound system check that too. is it one speaker sounding like crap or all of them? it could be alt. noise too or a loose antenna connection.

[emorabbit]

i would check all of your grounds on the radio and if it has the premium sound system check that too. is it one speaker sounding like crap or all of them? it could be alt. noise too or a loose antenna connection.

Nah, I've tested on stereo, aux, and CD. Don't think its the antenna. This noise is coming out of every single speaker. Although that would lead me to believe its the mono "Mega-ground-wire," I'm still not sure where that's at. I think I might have found it replacing the master brake booster, but everything on that seemed to be secure. Where is the ground wire for the stereo in this car? I used an aftermarket wiring harness to ease installation if that helps.

[85crownHPP]

I hard wired the ground to a handy set of ground tabs I found in the inside firewall on mine... any dedicated ground will work, as our cars have the evil common ground for the stereo. Its best to hard wire the speakers too.
Its sounds to me like the noise maybe be a bad connection or ground for one of your noise capacitors... there's one for the coil, and if you happen to have an externally regulated alternator, one for it (on the regulator). Could just be one of those is unplugged.

[gadget73]

yeah, I ran mine to a handy dandy nearby screw as well. Not sure where the in-harness ground goes, but it looked wimpy.

Window issue sounds like maybe a bad switch at the passenger door, but it could be an issue at the master switch as well. I'm guessing you mean to say it goes up and down using the master switch, but only goes up using the passenger switch?

No second fuse box. Theres the bundle of fuse links under the hood at the starter relay, and what you see under the steering column. Nothing else hidden away.

[emorabbit]

No, the passenger has 0 control over the window at all. However, i did find out today that if the switch on the passenger side is pressed up or down, i cant control the window from the drivers side master. How would i go about hard wiring all the speakers? And what if the ground wire thing is connected and all things seem secure, what is that big piece that all the grounds plug into grounded to? Because it would seem to me that is the problem. Thanks for the help so far guys.

[gadget73]

Is the 'lock' switch flipped? That disables the passengers in the car from controlling their windows.

[emorabbit]

Is the 'lock' switch flipped? That disables the passengers in the car from controlling their windows.

Nope, flipped or not flipped, the passenger side will not move with the passenger switch. Anyone have any idea why only one side would work, and the problem isn't the motor, or the fuse box.

[gadget73]

switch problems. Both need to be good to work, it sort of runs in series through the both of them. Probably the master switch is the issue if I had to guess.

[emorabbit]

switch problems. Both need to be good to work, it sort of runs in series through the both of them. Probably the master switch is the issue if I had to guess.

Any idea where i can pick up an OEM or new master switch? Cause my plate for mounting the switch is broken too, so one out of a junky wont do.

[yucatecd]

Dear Panthers,
Can I get noise capacitors from the dealer. I'veupgraded my alternator to mustang. Do I need one for it as well?
Donald McCaig

[gadget73]

Brand new switch? Not sure if those even exist anymore. Probably lookin for a replacement on ebay, or going to a junkyard and getting the switch and the plate.

[emorabbit]

Brand new switch? Not sure if those even exist anymore. Probably lookin for a replacement on ebay, or going to a junkyard and getting the switch and the plate.

Well, advanced wanted 30 bucks for one... Napa wanted 15, so ill be picking it up from napa in the morning. Advance was out of stock and wanted twice as much... Go figure. Napa will have it there in the morning for half the price. Ill tell you how it goes, i figure it wont work. Tightened all the grounds to that hideous mega ground plate that comes off the frame... The wires were loose until i made them stay still with a set needle nose pliers. I'm just trying to help anyone else with similar problems if i accidentally fix this mess ^.^

[emorabbit]

Alright, so went to go put the part in today after i picked it up. And as i figured, it didn't work. Got frustrated and pulled apart the entire door, figured out that i had to tap the motor with a screwdriver and the window is now working. I figure that ghetto job with the speakers in the doors might have managed to make something get caught because of the loose negative wire (Just fixed my speaker problem and window problem, because it was the same problem.) Thank you, and goodnight.

[87_crown_vic]

hmmm... i forgot about that issue.... the worn part in the motor when motor is old... i never roll windows all the way down due to fact they dont like working when they are all the way down unless i tap the motor.