Drive it forever : 42-volt systems good idea, but …
Dear Mike: Several years ago there was a lot of talk about the possibility of changing cars from 12-volt to 42- to 48-volt systems. Is it still under consideration or was it found to be unfeasible? — J.S., Jackson, Miss.
A: Yes, 42-volt electrical systems were supposed to be the wave of the future. Current automotive systems, which we call 12-volt, actually operate at about 14 volts, so the proposed 42-volt systems are triple this voltage. Most aircraft have operated at 28 volts for generations.
The advantages to upping the voltage include the reduced weight of wires, motors and actuators throughout the vehicle, as 12-volt parts need to be larger to carry enough current to get the job done.
The conversion meant integrated generators and starters built into the flywheel, air-conditioning systems with an electrically powered pump mounted anywhere except inside the engine compartment, and electric (not hydraulic) power steering.
Didn’t happen, isn’t gonna happen. Why? Seems the industry couldn’t make 42-volt systems as reliable as they thought they could.
DC voltage is constant, and simply yanking a switch open starts an arc that rapidly degrades the metal contacts. At 12 to 14 volts, the arc is small enough not to be an issue. But at 42 volts, the erosion of the contacts shortens life span too much. Switch contacts can be upgraded and electronically protected from this — but it all costs money.
Dear Mike: I have a 2004 Buick LeSabre Limited with about 40,000 miles on it, and recently noticed that, when the engine was hot, the coolant was down to the “add coolant level.” I went to my local auto supply store, and they did not sell the GM version. But the store had a new Prestone version that claimed to be all right for use with any other coolant.
I called my dealer, who told me that it was OK to add that. I added about 1 liter of 50 parts water to 50 parts coolant, even though the directions stated that one could mix it with as much as 70 parts Prestone to 30 parts water.
I went to the Prestone Web site, and they did have something about their new coolant version and again emphasized that it could be mixed with any other type of coolant.
Are you familiar with this “new” version of Prestone? In the past, you advised readers not to mix coolants — would this new product cause you to modify your restriction on mixing coolants? Or should I now have my system drained, flushed and reconstituted?
A: If the coolant you added uses the same type of additive technology — organic acid, referred to as OAT in the industry, it is in fact the same type as the Dex-Cool that General Motors installed in your car at the factory, and you’re fine. Read the label.
Dear Mike: I have a 2004 Envoy with the standard FM radio and a single-disc CD player. When I went to upgrade the player (with a non-GMC product), I was informed that the radio could not be removed or replaced, as it controls the air bags.
Is this true? If so, is there a way around it? I wanted to do this, as there are no GMC satellite/CD players with MP3 capability.
— R.B., via e-mail
A: The air bag system has its own dedicated wiring harness that has nothing to do with the rest of the truck’s wiring or the radio. Maybe somebody is confused because the original radio has volume and station-changing controls built into the steering wheel, right where the pyrotechnics for the air bag are housed.
The new radio may not be compatible with the air bag’s components — but that won’t affect the air bag operation.
Dear Mike: Why would a car with “Automatic Self-Leveling” become frozen in cold weather? It is so bad that it makes the car ride as if the axle is welded to the frame! It’s unsafe to drive like that since the axle hops and even the traction control becomes activated. The car in question is a 2000 Cadillac Catera.
A: Water in the system is freezing, making the suspension immobile. The question your mechanic should address is how it got in there and how to keep it from getting in again after it’s dried out.