Hi all,
so I have had my car for a few months without issue, suddenly the other day when using the drivers rear power window while running it would noticeably affect the car and bog down the motor and also temporarily shut off the radio Then after several tries it stopped. Now today when attempting to put the top down the same thing happened killed the radio, but the window switch worked fine. Does anyone have a thought on this?
thx Mike

 

I'm going to suspect you have an aftermarket radio. Many of the aftermarket radios have a higher wattage output than the OEM AM, OEM AM/FM, OEM Tape Player combinations. And, if you have a subwoofer and/or add-on amplifier installed, you have a much higher wattage demand than any OEM equipment installed on these vehicles (assuming you have OEM alternator/voltage regulator). The electrical demand is high if you have the radio running during normal OEM electrical operations i.e. putting the top up/down (convertible), power windows/seats, etc.

You might examine if the radio is wired correctly. I know my AM/FM/USB stereo radio is wired correctly but certainly has a higher wattage output (and electrical demand) than the OEM radio. When I have the stereo cranking, the electrical draw-down is appreciable. I do one of two things: (1) turn the radio off - this quells the issue or (2) raise the RPMs on the engine to compensate for the electrical demand.

Suggestion: turn off the radio before you raise/lower the top and/or use the power windows. That's really about all I can say without getting into beefier generator/voltage regulator, etc.

 

Some other suggestions are:
Check the charging system at rated curb idle. See what the voltage drop is when the (or any) load is applied.
You're either taxing a good alternator or have a bad one?
Grounds grounds grounds....Check all grounds. A 47-8 year old car will have bad grounds and positives, even a desert car will.

Check the current draw on the window motor circuit. What is it? Obviously not popping a fuse. Make sure the right amp fuse is there. Someone could have had the same problem and installed a heavier one.

Check the motor, the wiring to it, and the switch. Any or all 3 could be nearing its life expectancy. Isolate each assembly and test voltage and resistance.

The window regulator could be dry or bound.

If you do in fact have new digital radio they arent forgiving like an old analog radio. If the voltage drops below its low volt threshold it will shut off.

 

Also inspect all wiring and connectors in general, to see if any burnt or hacked up areas - old wiring can sometimes cause problems that may only be corrected by replacing the affected harness. Your top feeds off of the intermediate harness running from the top motor, under the driver seat carpet up to the dash by the E-brake pedal assembly. There's also a separate harness under dash that connects to the top switch. I also concur with the idea if upgrading your alternator if additional power draw demands are indicated.

Luckily all of our harnesses are reproduced through reputable sources - I also have a '72 CS ragtop and have replaced just about every harness - absolutely worth it for the improvements realized over the 47yo harnesses they replaced.

 

So it’s weird that’s it’s not consistent, today there was no issues from either. Also I was looking up a new alternator and was asked if my regulator was built in? Is it the guy at the parts store said it should be and it’s also a 64 amp alternator if it’s built in

 

It's possible (I suppose) they made two different Alternators for the 72 model year. But when I look up the location of the voltage regulator for a 1972 CS, the FAM clearly demonstrates an external VR. I 'think' this is the location for a non-AC vehicle, but I'm not positive about this. Others will surely know better than myself. I can tell you w/ 100% certainty the following image is from the 1972 CS CSM. Additionally, RockAuto sells about six different external voltage regulators for the 1972 CS.

 

So I will check this weekend, I wonder if it’s different because I have AC

 

If it's any help my '72 convertible with air conditioning was born with an external regulator as seen in the diagram above.

 

All 1972 Oldsmobiles except Toronados got an external regulator charging system from the factory, even 442s. The 1972 alternator is unique in that it uses the same case as the internally regulated 10SI from that period, but the plug is different.

 

It's a simple swap to change over to an internally regulated alternator - essentially just 2 simple adapters - a $3 connector for your engine harness to plug into the alternator and you can eliminate the external VR from your firewall. the other, made by M&H (and American Autowire, I believe) bypasses the VR connector for the swap to work - cost is under $25 if I recall.