Stupid cheap Chinese radio not working as advertised

[7milesout]

I have come to this hypothesis ...

I think your hypothesis has merit. However, regarding the alternator, the 3% to 7% fuel efficiency increase / decrease sounds excessive to me. Way excessive. I have respect for your vehicle knowledge though, so don't get me wrong. I'm just flying by the seat of my pants with my "excessive" opinion.

Most people don't believe an A/C compressor lowers mpg by 3%. Yet I think the A/C compressor is probably 3 to 10 times the amount of load than is the alternator. But I don't know that factually.

I would like to test my theory, I think there's a decent way to do it. The drag strip. The trap speed + established formulas are very accurate calculating hp at the tires. If I ran it with and without the A/C, I bet the trap speed would definitely define the hp required to run the A/C. The problem with running it at the drag strip is ... well, ... it's a Mirage. And people would point, and laugh, and snicker, and whisper, then laugh some more, then ask me why I was there, then laugh, then a gang of rednecks would drag me out of the car and give me the beatdown (like the bullies on The Simpsons). If I could only drag race it when noone else is there. I think most of the rednecks there have no idea the value of the numbers on the slip. However, some of the biggest, mouth-breathing, knuckle-dragging Neanderthals you'll meet at the dragstrip have really high IQs. You just have to wade through all the others to find the smart ones. I can profile them like that, because I'm a clone of those that I just described. I make Shrek look pretty.

[mohammad]

I think your hypothesis has merit. However, regarding the alternator, the 3% to 7% fuel efficiency increase / decrease sounds excessive to me. Way excessive. I have respect for your vehicle knowledge though, so don't get me wrong. I'm just flying by the seat of my pants with my "excessive" opinion.

Most people don't believe an A/C compressor lowers mpg by 3%. Yet I think the A/C compressor is probably 3 to 10 times the amount of load than is the alternator. But I don't know that factually.

if we say that the car uses maybe 409 watts of power. This is a reasonable estimate considering low beams are 110w, 30w of parking lights 50w for the blower motor, 50w for rear defogger, then the rest towards interior gizmos, lights, the engine.

If the alternator is approx 55% efficient we can estimate 745w load on the engine, thats 1hp.

Based on inuviks post we can see that 60mph at 2000rpm cruise is possible: https://mirageforum.com/forum/showth...ll=1#post31048

Looking at a dyno chart: https://mirageforum.com/forum/showth...ll=1#post38303 2000rpm is approx 25ish HP.

Now we know we need 25 hp to cruise at 60mph and we need 1 extra hp to run the alternator 25/26=0.96 Therefore at 60mph we would save 4% of our HP and Gasoline if we didnt use our alternator. The savings of couse get better at lower speeds and worse at higher speeds as alternator uses a larger percentage of the power output at lower speeds.

Im sure all this information is available on the thread i originally linked here: https://mirageforum.com/forum/showth...for-better-MPG

[mohammad]

Minor update: I am now highly confident the issue is related to the illumination circuit. The issue does not occur when the parking lights are on. The issue only occurs when brakes are pressed, parking lights off and vehicle is in motion. Ive only seen it occur a couple of times while stationary but it is fairly consistent while in motion. Im not sure how being in motion would change anything unless some sort of regen braking feature is at play.


Either way brake lights have been ordered from rock auto and ill post an update when i install them.

[mohammad]

I feel like I should probably finally get around to trying to fix this. Does anyone know how the brake lights are grounded?

page 90-98 in the FSM has a wiring diagram but I dont understand how the ground wire is run?

page 54A-107 says I should try and measure the ground resistance and see that it is under 2 ohms but it doesn't say what to use as a good reference for ground. I guess instead of being lazy the easiest thing for me to do is measure the resistance of the ground on each of the two brake lights and compare them.