Freddy B

Ok I am still troubleshooting the issue of why my aftermarket stereo shuts off when ever I raise or lower my top on the 71 cutlass. I have connected the top directly to the battery and tried to raise the top and the radio shuts off yet again. I connected a test light to the top motor and I was getting voltage on the lead that lowers the top when I was pressing the switch in the direction to raise it. When I press the switch in the direction to lower the top I was getting voltage on the lead that raises the top is this suppose to happen? I check to see if there was a continuity or infinity reading from the wires coming from the top motor, the reading was continuity. Is the top motor bad if I get continuity when I check to two lead coming out of the motor? Also when I raise or lower the top my voltage at the battery drops to between 7.6 - 8.4. Were do I go from here?

joe_padavano

How about some additional info? I assume this radio uses an electronic on/off function, as opposed to a mechanical switch. That makes it susceptible to interference. Does your aftermarket radio have a wireless remote? Could you be getting EMI from the top motor that's triggering the shutdown? How did you wire power to your radio? Best bet is to run the radio power feed directly from the battery. That eliminates potential interference.

Freddy B

I have ran the power wire for the radio directly to the battery and I still am having the same issue. When ever I use the raise or lower the top my battery voltage drops to 7.6 - 8.4 volts. Should the top motor wires have continuity or should their be an open circuit when I test it with a multimeter.

jaunty75

Your radio is shutting off because the voltage drops too low for it. Your power top motor is drawing too much current. My guess is that this problem has nothing to do with the radio or how it is wired, and the fact that it turns off is just a symptom of a different problem.

I don't know anything about the wiring of the top motor, but I suspect that it is either wired incorrectly or for some reason is drawing too much power. It could be that the motor is failing internally or that the top itself might not move as freely as it should and the motor is working too hard.

But if the radio shuts off the moment you push the top switch, I would suspect improper wiring or a failing motor as I would suspect a top not moving freely would take a few moments to bind and then draw too much power, so the radio would not turn off immediately when you touch the top switch.

MDchanic

As I said on August 7th in response to your post "Convertible Top Short Circuit,"
Your measured 7.6 to 8.4 volts while using the top motor confirms that your voltage is dropping enough for the radio's electronics to turn it off.

I notice that you have also posted threads entitled "71 Convertible Top Motor Wiring," and "71 Cutlass Radio Shuts Off When Braking."
It seems to me that this is all one problem.
How is your battery?
What is its resting voltage?
What is your system voltage at idle?
At 2,000 RPM?
How old is your battery?

My first thought here is discharged / bad battery.

- Eric

stellar

I agree. Get a battery and check charging system. If volts are dropping that low when top motor is running, you would be drawing BIG amps. I would guess around 350. That would smoke the top motor and wiring.

MDchanic

EXACTLY.

- Eric

TripDeuces

Sounds like a bad ground issue

MDchanic

Possibly, but where?

It would have to be in the charging system - alternator, battery, or engine to frame - to do this.

- Eric

TripDeuces

I'll start with the obvious: body to frame, battery to body, radio ground, top motor ground, bad wires, brushes on the electric motor, bad connections, etc.

There's a drop of over 4v, that's huge, it has to be going somewhere. Only a small amount (tenths of a volt) should be eaten up by resistance and or heat. When 1/3 of your voltage is going away it's sure not your radio that's the problem. Personally I'd be looking at the top motor.

MDchanic

Yes, but, it can't be the radio connections (as you say, too much of a drop - it wouldn't work at all if it was that bad), or top motor connections or brushes, because if it were, the motor would draw LESS, not MORE. Also, if the motor WERE drawing enough to pull system voltage down that far, as has already been pointed out, it'd melt the wiring.

Until proven otherwise, I'll stick with bad battery, or bad charging system connections - battery terminals, battery cables, alternator connections, grounds to battery or engine to body. Check the battery or swap it with a new one from a buddy, and check voltage drop across all important connections, as well as charging voltage.

- Eric

TripDeuces

Well we don't know if the wires are melted at this point. We're talking resistance due to bad connections and or grounds here.

I had a hot start problem on my 70 Toronado back in the day. Started fine everyday but once hot it would barely turn over. No visible problems anywhere. So I removed every connection between the battery and starter and the grounds and cleaned them all. Never had the problem again. Bad grounds and connections caused high resistance in the wiring and reduced voltage to crap.

The only reason I don't think it's the battery is if it lost its charge the radio would have stopped working all together regardless of the extra drain from the top motor. I would go through every connection on that top motor and clean them all as well as check each wire for resistance which may not be visible.

Here's another story: When I worked at a local auto parts store a guy came in looking for a battery for his 67 Chrysler 300. He asked for the biggest battery I had so I gave him the 1100 amp model. Next day he's back complaining the battery is junk. I told him that battery could start 5 of his cars at once so let's go take a look. His connections were tight and all looked well from all outward appearances. That was until I grabbed the ground cable. Green copper powder literally fell from the lead. There wasn't a bit of pure copper left in that wire, just copper oxide powder. A perfect example of good connections and high resistance.

How many old school guys on here have turned that little plate around in their starter solenoids back in the day for a better contact patch because the one side had become pitted where the brush contacted it? Of course now you can't do that because of the cheap crap made, it was common place back then and easy. Also cheaper than buying a solenoid.

I give advice here based on my experiences and knowledge. I'm not looking to get into a debate over how electricity functions. A forum member had an issue I offered advice, take it for what it's worth.

jaunty75

Great story! Had me laughing out loud.

Lady72nRob71

The positive cable on my Harley did that. It was in a position (at the starter) where any water would run down the cable, get into the connection, sit there and corrode the cable away... Luckily the no-start problem surfaced in my garage.

I agree about the connections being the likely issue for the OP's problem.

MDchanic

Hey, I'd love to argue with you, Trip, except, unfortunately, it looks like we agree . I just think there's a lower chance that the problem is in the motor connections than the charging connections (or cables). He clean and check the drop across all of them.

- Eric

TripDeuces

I respect your knowledge also. Plus you live in my home state so I have to cut you some slack. After all you are a Maineiac.