Radio questions


Well-Known LVC Member
May 19, 2007
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I've had some dashboard electrical problems (tach and gas gauge sometimes don't work with the headlights on) so I'm devoting time to it. I've been wanting to update this cassette / radio too.
I pulled the radio out. There was something behind it. A small amplifier? It was not secured. It's just hanging loose behind the radio. Also, there was an ON-OFF switch stuffed back there. Looks like a Ford switch. Wrapped masking tape made sure it was ON all the time.
Someone spliced in heavy speaker cable, as if a lot of watts was running through it, to some speakers. Those cables are now marked Left-Front, Right-Rear and so forth.... Perhaps a radio / speaker installation was later removed, and OEM stuff replaced?
Anyone know what that "amplifier" actually is? Can this radio live without it? How many watts per channel does this radio have?
And what is the On-Off switch for exactly....?
30 rad.jpg
You know me from back in the day.
I'm still one of those, "purist" that has all the answers about stock stuff :)

The switch is ~not~ OEM. I can only guess that it has something to do with the aftermarket Anti-Theft system.

As for the other pictures, it all looks correct to me.

Let us all know how you proceed and what you find.
Thanks for the confirmation OldSchool.
Searching manuals, I see a "four channel amplifier" (possibly JBL) in some wiring diagrams. So it's an amp. Its mounting holes do suggest it was mounted under something, rather than behind the head unit.

The fat speaker cables make me think someone formerly replaced everything, but ripped it out and reinstalled the stock stuff , to sell the car...

Some things are a problem. The antenna cable barely reaches the radio. It's stretched real tight, and I've had reception troubles.

This switch sure looks "Ford" to me.. it's the right age, and everything... I'll trace the wires tomorrow.

I'll be working on it tomorrow, and may visit the local car stereo store, while everything's exposed. Pick their brains.. Perhaps have them install a modern radio.. Bluetooth, Aux inputs, USB ports, etc.


"Your local stereo store should have an antenna extension."

Thanks. Good idea. That's an easy fix..

Meanwhile, my headlamp / instrument panel dimmer switch is toast. I disassembled it. Broken plastic and a missing metal wiper arm. Headlamp part is OK.

This broken dimmer is probably the source of my suspected "bad ground", which kills the tach and fuel gauge whenever the headlights are on. Last week, while messing with the dimmer dial, the tach and gauge problems suddenly disappeared, for a while. Instrument panel has been dimly lit, at best, for years.

No switch available at auto parts stores. Can't find a wrecking yard Mark7 within 100 miles.
I'll try and bypass this dimmer. Rewire things so the dimmer is no longer in the circuit. Then the panel lamps are at full brightness whenever the headlights are on.
It's disassembled. The wiring is straight forward, but I need to be absolutely sure that my modification is correct before hooking it up. I don't want to fry any wiring.
The main square plug has several connections.
The dimmer element (looks like a spring, partly visible in one photo) has its own separate, single-wire plug / connector. (Silvery tang, not copper.) I'm pretty sure this one wire powers all the panel lights. I have the car's "Wiring and Vacuum Diagrams" so it's only a matter of being careful and patient...




For that switch, see Tom Curry at - Home

Thanks .. I'll check that out.

Calling around today, I think AutoZone had a "switch" for me, but it was the wrong thing. It was also $57 ("It's in the warehouse, and you can get it today!") I'm not anxious to spend a lot on this.

Times are rare when I drive long distances in the dead of night, and desire to dim the instrument panel.. I can live without it.

Thanks for searching that out..
I have an '88 LSC.
I'm reading the '88 Service manual, and cannot find the switch pictured in your link. The Cougar, T-bird and Mark VII all use an integrated switch; There's the rocker for the headlamps / parking lights, combined with the dimmer-wheel on a single block of plastic.... Like mine in the above photos.

I guess the " Panel Dim Dimmer Switch" is probably unique to the 90-92 years? One of the little things they changed along the way..

Anyways, hopefully I got this all figured out. All I need to do is solder a wire between the end (of least resistance) of that coiled dimmer element and its companion contact point. That's where the lamps are brightest.

Also, position the wheel at the high point, and epoxy it so it cannot be accidentally moved. (Nope.. wrong. Turn it all the way, and the interior courtesy lamps turn on. They would always be on if I do that.)

Hook it up, connect the battery, and pray.

On a hunch I looked up the local Pick-n-Pull and they have a '89 TBird in the yard. It should have the same switch. Also have an '86 Cougar. I've taken chassis parts from the Mercury Cougar before... Worth taking a look...
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So, if you can't find the right part, you should still be able to wire in a rheostat from a similar vintage car to enable you to dim the lights. Leave the original switch in place to operate the headlights/parking lights/cabin light, then add the new dimmer out of the way under the dash somewhere where you can get to it to adjust the brightness, but not somewhere where it is an eyesore.
...wire in a rheostat from a similar vintage car to enable you to dim the lights. Leave the original switch in place..

That's entirely possible and opens up other possibilities.
I haven't soldered this thing yet. I might also solder two spots on my rheostat, instead of just one. One "bright" and one "dim. Then add a simple switch, to switch between them.
The fuse behind this stuff is only 5 amps. Not a lot of current to worry about... Any little switch would do.
I'm aware of the dangers. Emergency welding with a car battery and jumper cables when you're stuck in the boonies.... The 5 amp fuse tells me it will blow long before any damage is done to my wiring.

I'm not gonna try anything tricky here. One of these days I'll come across a proper switch, and install it.

Right now, the plan is minimal. Bypass the resistor and its heat-sink. Take them out of the equation. 12 volts will go directly to the panel lamps whenever the headlights are on.
I got the console reinstalled, and traced that switch. It leads to that amplifier. It is definitely a Ford switch. (See photo) It's wired directly into this amplifier (?!?).

To refresh memories, the amp was stuffed behind the radio, inside the dashboard. But the amp was originally mounted under the rear deck / package tray, with the rear speakers?

The On-OFF switch was also stuffed behind the radio, out of sight. It had masking tape wrapped around it, so it was "ON" permanently. Why would an amp need a switch?

I know almost nothing about stereos, and this car's has been modified in ways I know not. One set of cut wires coming out of this amp is labeled "Right Tweeter". Far as I know, the car has just 4 speakers and no dash tweeters...

Putting it back together may be beyond me. I think I'm gonna just take it to the local car stereo guys...


Radio issue
You are correct, that is indeed a FORD switch. However, Lincoln Mark VIIs from 1984 to 1992 did not leave the factor with ~that~ switch... ANYWHERE on the vehicle :)
Without a wire diagram, I cannot tell you what's on that circuit. There's way too many modifications there for me to be of help.

Dimmer Switch Issue
Dimmer switches did indeed change... twice.
1984 - 1987 FULL Heat sink
1988 - 1989 Partial Heat sink
1990 - 1992 No heat sink
The 1990 - 1992 failed the earliest.
I'm glad that you understand the importance of just HOW to by pass it and what the consequences are for incorrect wiring. It still wouldn't hurt to temporarily install a few inline fuses JUST IN CASE anything crosses or grounds.
Without a wire diagram, I cannot tell you what's on that circuit.

I should be grateful to have the wiring diagrams. Eight big sheets, like blueprints, printed on both sides. However, I've never enjoyed electronics or liked music (no talent for either) so straightening out this radio is just a chore...

Diagram says the switch's black wire traces to a power antenna motor. My antenna switch is on the dash, where it has always been, next to the rear defrost switch.
So, that mystery is somewhat solved. They added an unnecessary antenna switch. And probably found the car's original switch.... Then, rather than remove it, they just taped theirs to be ON all the time, so there was electrical continuity.

I don't mind struggling through this for the sake of the car. It's nice to have everything more or less "stock". However, this radio is real old technology. No integrated circuits.. It's all discrete components.
In '88, Lincoln called it an "Electronic Radio" because it's new, and superior to vacuum tubes....

If I knew I could spend like $100 for a good quality, drop-in, modern, radio-amp, with all the goodies, and just hook my speakers up to it, I'd have a real hard time continuing this job...
If I knew I could spend like $100 for a good quality, drop-in, modern, radio-amp, with all the goodies, and just hook my speakers up to it, I'd have a real hard time continuing this job...
You can talk to a shop and, "... spend like $100 for a good quality, drop-in, modern, radio-amp, with all the goodies, and just hook my speakers up to it..."
The schematic you have will show THREE possible power sources! That alone is why I've tried once and failed once to correct an aftermarket install.
....THREE possible power sources!

This dimmer is reinstalled. No smoke or crackling sounds coming from the dash. Everything seems to work. I'll do a thorough lighting check when it's dark outside.
Darkness. The right rear low-side parking lamp is burnt out. The You-left-the-key-in-the-ignition warning bell rose from the dead. Test drive tomorrow.

..found another wire flopping around inside the dash, labeled "Always hot". I'd really like to clean it all up, and install a good stereo.
Studying radios, so I don't get ripped off too badly at the stereo store. Preamp outputs. Crossovers. Speaker-level inputs.

Question: Is there some trick to disconnecting these connectors? Whoever invented these things was a sadist, imho.

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