The problem with my radio antenna is not the mast. I can get the motor to spin by feeding power directly to it when it is on the workbench but it will not work when put into the car. I have tracked the culprit down to a black box that is affixed to the mast above the motor. There are only three components to the system, the motor, the winding gear, and this black box [in addition to the mast itself]. I am assuming this box decides how far to retract the mast but am not sure.

I am considering cutting open the box to see what is inside and to see if it is repairable. Has anybody done this? Would like to read about your experience.

Did you ever resolve this issue? I want to put away the one on my workbench if you're all set.
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Art Benstein near Baltimore

Only Irish coffee provides in a single glass all four essential food groups: alcohol, caffeine, sugar, and fat. - Alex Levine

Noticed you are still fighting this issue when you posted in an unrelated thread. I'm curious about some details left out of this thread: Does the red/green wire have battery constant on it? Does the black wire have zero on it? Does the red wire then have battery when the radio is turned on? Your original post wasn't specific about exactly what the in-car conditions were on those three wires.

I still have that junkyard antenna on the workbench, and can help you by referencing its behavior if you like.
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Art Benstein near Baltimore

"I was worried that my mechanic might try to rip me off, I was relieved when he told me all I needed was turn-signal fluid."

Have you run power directly to the black box?

If applying power run directly causes the antenna to raise and lower correctly, consider adding a switch and a wire to power the antenna If you cannot find the problem.

As Dave mentioned, one of our 740s had a switch on the dash to lower the antenna when the radio was on. This was not an aftermarket switch, but a Volvo switch marked in a similar manner as the other switches.

The only reasons that I can figure its purpose is that you can lower the antenna while in the car wash and want to listen to the radio, or perhaps while listening to a tape.

Doh - sorry Dave, your answer is perfect, mine is unnecessary.

I presume you're talking about a sedan and not a wagon. I can't say as I'm overly familar with power masts in the early 940 sedans as my 940 wagons have the antenna in the rear qtr panel window and use an amplifier in a black box near the wheel well that gets it's power from the antenna mast signal, but the principle should be the same.

If the power mast now works with directly applied voltage then obviously the problem lies earlier, either in the radio itself or the wiring harness.

Rather than waiting for a reply from you, I'm going to cut to the chase and assume this is not the factory radio. If that's not the case then you're best off trying to use a meter to fault trace the wiring starting from the rear and moving back toward the radio -to aid you, there a few proper Volvo 940 wiring green manuals that can be found on-line with google.

Presuming it's a replacement radio, you need to re-examine the wiring harness adapter/splicing -something may even have come loose if it was previously working. Many radios have a separate antenna output that you would normally connect out to the car antenna mast motor (or in the case of later 940 wagons to the rear window antenna amplifier). Check to make sure that any such output is still actually connected out to power for the mast. The output signal will normally have voltage to keep the mast raised whenever the radio is powered on, whether or not the FM radio tuner is actuallly currently selected. For those radios that do not have such a signal, you need to look for another (non-speaker) output signal from the radio to tie to the antenna motor. Once such signal you can splice to is power output to a separate amp. Failing that, you would have to ignore the radio and have the antenna mast motor tied to the ignition switch (KPI), which is best accomplished by just tying into the radio on/off power supply from the ignition switch (not the constant radio +12v supply from the battery that keeps the radio memory alive). When tied directly to the ignition switch, you may prefer to run it through a dash console antenna up/down switch so you have more control of the mast. The 740s had just such a switch in the dash panel, which as I recall was next to the dash illumination slider switch. It actually was a slave to the radio mast output, but for radios without such an output it would be a next best substitute.

Hope something in the above will help point you to a solution.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

In my situation I am referring to the picture. There is power to both plugs A and B. I can get power to the motor by hooking up to plug B when it is disconnected. I cannot get power to the motor when plug B is reconnected and plug A is connected to the car. This is why I am pointing at the mystery black box as a potential culprit.

I don't have any more time and I have tried three times to get the image uploaded. I will have to come back and give it another try. Can't believe how difficult it is to upload an image on this site.

Image?

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Keeping it running is better than buying new

There is a number on the black box: f19. Don't know if this means anything.

People don't seem to know much about the mystery box for you, so I'll tell you what I vaguely recall and some further info I just dug up (there is precious little out there).

The box is called the antenna control unit. I believe it contains flip/flop circuitry to raise/lower the mast (by changing polarity to the motor as dictated by the signal from the radio) and a motor load sensing circuit to determine when the mast reaches end of travel (rather than using something like microswitches on the mast). For your 960, it appears to be p/n 3533347 for 1992-1997 960s, which was superseded by p/n 9459713, both listed as no longer available. So just about any 4-door 960 in a yard should be a potential donor for the control unit box if you should need it, but of course most yards will only sell the entire mast assembly. Other 700s/900s of that vintage may well have a similar antenna motor and control unit, but possibly with a different connector.

Here are my further suggestions. Some of this you've already done.

Check that the control unit is getting +12V from the battery (doesn't go through the ignition switch so it's always there), Check for the +12V control signal from the radio whenever it is powered on to tell the control unit to keep the antenna raised. Probing into the motor connector may not show a +12V output anywhere (or possibly just briefly) even when the control signal is present because of the load sensing circuitry.

Make sure the motor or mast isn't jammed. If the motor can't turn easily then the control unit might constantly sense it's at end of travel so would no longer send voltage to the motor after a brief attempt before the load timer cuts it off. Open the gear and motor housing (best done off the car for easy access). Check that the mast sections aren't frozen. Clean out any debris in the gearcase (a bit of broken tail off an old mast can easily get jammed in there, I vaguely recall there's also a water drain hole that should be kept clear). Check that the motor can turn freely (a bushing may be a bit seized). Clean and lightly lube everything. The mast sections are best lubed and cleaned with WD-40 on a rag (as I recall the service manual suggests). The tail and gears can be lubed with silicone grease (dielectric grease will do fine). You should then be able to test the motor without re-inserting the tail. It may well keep running until you insert the tail and let it get pulled in all the way or it may have a timer to prevent constant run on (I can't remember).

Failing that and nobody coming up with a better idea then I'd say it's off to a yard for a used one.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

The image looked awfully familiar, though I don't own any 900 cars, so I looked through my hoard of PNP finds. Found one I pulled some years back to fix my daughter's 93 240.



It works exactly as you describe. The always on battery needs to be on the red/green wire, a ground on the black wire, and when the radio is switched on, battery on the red wire to extend the mast and removed to collapse it.

At least now I know where it is next time #1 daughter mentions it.

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Art Benstein near Baltimore

"If I am reading this graph correctly—I'd be very surprised." —Stephen Colbert

image try. I might have the image uploaded here. I really don't know.