46
votes
Accepted
Why don't cars have circuit breakers instead of fuses?
(1) Fuses are cheap. Really cheap. You can get a variety pack of 100 for $8 or so. Circuit breakers for 12V systems are available, but are not cheap (more like $10 each). My car has 40 or 50 circuits, ...
- 576
14
votes
Why don't cars have circuit breakers instead of fuses?
I don't have a definitive answer, but believe it is a combination of factors and boils down to the following:
Cost: While both do the job of protecting circuits, a fuse runs you cents per unit, while ...
- 153k
12
votes
Are mechanical relays still used for turn signal circuits? If not, where does the clicking noise come from?
In my car the indicators are controlled with solid state electronics and so could switch silently as there is no relay or bi-metallic strip contactor to make a noise as they are activated. There is ...
- 263
9
votes
Accepted
Reliable 12V supply in car
When properly installing an amplifier a large gauge wire is run from the battery to trunk area. A fuse is installed as close to the battery as possible. The amplifier then connects to that wire. If ...
- 16k
8
votes
Why do cars still use mechanical blinker relays?
I can think of several reasons straight away:
Cheap
Easy to replace
Have a very distinctive click that makes it obvious when they are on, and when a bulb has failed
Are very well understood
Anyone ...
- 18.6k
8
votes
Why don't cars have circuit breakers instead of fuses?
In addition to the other good answers:
You'll see self-resetting circuit breakers in heavy-truck applications, which is a far more abusive environment, and prone to intermittent faults (esp. in ...
- 311
7
votes
How stable is voltage in a 12V car outlet?
ANSWER: Pretty unstable.
Connect a voltmeter to your ciggy lighter socket, and watch it while starting and running the car. It will be ~12.5V when the motor is off, up to 14.5V while just started, ...
- 2,838
7
votes
Accepted
Are all drive-by-wire cars completely (brakes, clutch, gas, steer) by wire?
If the car is drive by wire it doesn't mean everything
There are some cars that are drive by wire where it's the accelerator only.
Brake by Wire
If it's an electronic brake system the term EBS or ...
- 33k
7
votes
Accepted
Simplest installation of car-powered car-pc
Most everything external of the ECU is going to be 12vdc (+/-2v). (NOTE: As @juhist points out, more and more cars are supporting 5vdc output to charge handheld devices through USB ports. 5vdc may ...
- 153k
7
votes
cigarette lighter is always on
This behavior is by design and it was the same on pretty much any Ford of that era (at least it was on the Mondeo, Fiesta, Fusion and Focus IME)
You can modify it to come on with the ignition but not ...
- 9,989
7
votes
Control Systems of Modern Engines
Another way to go would be to check out Speeduino.
It's an open source DIY ECU.
The software is freely available here: https://github.com/noisymime/speeduino/ and it can run on an Arduino.
If there's ...
- 196
7
votes
Accepted
Battery Relocation to Trunk Pros & Cons?
I think you have most of the stuff covered as far as pros/cons. The "main" reason people do this is weight distribution, as you stated. This is for the performance to place more weight in ...
- 153k
6
votes
Fixing a water-damaged remote key
I accidentally ran the smart key for my '09 Jaguar XF supercharged sedan through the washing machine once. It was submerged in water for about 10 minutes until I found it. I was able to fix it by ...
6
votes
what sensors and formula are used to control VGT/VNT turbos?
Dodge installed VNT Turbochargers on cars in 89 and 90. The most well known of which is the 1989 Shelby CSX-VNT. The vanes were controlled by a dual port vacuum actuator. There was nothing ...
- 8,443
6
votes
Accepted
Tapping into the on-board computer
You cannot easily "tap" into any ECU/PCM. Depending on what year your vehicle is, it could be a simple set of analog gauges which you could tap into the signal line, but you'll need to do some ...
- 761
6
votes
What happens if I disconnect the battery while the car is running?
When a Battery is disconnected from a running engine, there is a milliseconds high voltage spike that occurs the instant the terminal leaves the battery connector. Some researchers say it can be as ...
- 61
6
votes
Accepted
Why did the old-school thermal flashers remain in use for so long?
Three major reasons why they were used so long:
1. Cost - Even today a thermal flasher units cost about $2-2.50. The cheapest equivalent electronic flasher unit, which happens to be a direct ...
- 153k
5
votes
Tapping into the on-board computer
If your car has a OBD2/ODBII port then it is achievable. I'd imaging the simplest way would be to use a ELM327 type cable or even a bluetooth adapter to provide the interface between the pi and the ...
- 341
5
votes
How to control a car (accelerating, braking, steering) programmatically?
No car has every attribute to be fully autonomous out of the box.
Brakes: If a vehicle is equipped with dynamic stability control then software control of the brakes is possible. Dynamic stability ...
- 16k
5
votes
Accepted
Which electrical parts in motorcycles are obligatory for basic driving capacity?
Generally manufacturers aren't going to waste money on unnecessary components.
You've got electrical components to:
provide spark to the engine.
an on/ off / kill switch to control engine on or ...
- 6,569
5
votes
Accepted
What happens if I disconnect the battery while the car is running?
Removing the battery with the car running is a bad idea. Rather than re-writing something which exists on the interwebz, I pulled this from Troubleshooters.com under the section called Automotive ...
- 153k
5
votes
What's wrong with using domestic flex cable for automotive purposes?
Automotive cables are normed (ISO 6722 ?).
The insulation of automotive cables offer a superior resistance to heat, cold, chemicals and vibration.
A common FLYR-cable should guarantee its insulation ...
- 8,448
5
votes
Are mechanical relays still used for turn signal circuits? If not, where does the clicking noise come from?
In the old days, the flasher used to be controlled by a little device that contained a bimetallic strip. When current was supplied to the flasher lamps, the strip would heat up, bend and turn off the ...
- 24.8k
5
votes
Accepted
Should ground wires be fused?
I have fitted many accessories to cars, trucks and agricultural vehicles, some taking less than 1 amp and others several hundred or more.
I have never put fuses on the earth or ground side. If the ...
- 34.6k
5
votes
Control Systems of Modern Engines
Yes, do some research about early fuel injection systems and electronic ignition.
You will find Bosch had some superb info about how they worked etc with really good diagrams and detailed explanations....
- 34.6k
4
votes
Accepted
How to diagnose undervolt in electrical system
There are several things you can look for:
Complete paths
Electricity requires a complete path from positive to negative.
In a car with that kind of age, I would be checking that you don't have bad ...
- 9,326
4
votes
What voltage does the ECU need?
If you're talking about a regular 12V battery vehicle, then the ECU is likely to work from 7V until 14V with no problem. That's the usual requirement for this kind of component.
- 217
4
votes
What happens if I disconnect the battery while the car is running?
If the car has electronic components, like ECUs, central commanding modules, etc, doing that "may" fry them...or not. Sometimes the ECU turns off the engine if the battery is non present. Same reason ...
- 3,336
4
votes
What happens if I disconnect the battery while the car is running?
The answer is a bit complex here:
As Paulster2 has mentioned, the battery does help protect from transients, but as the alternator has its own regulator and the computer and audio system have their ...
- 718
4
votes
Accepted
Defender Right Indicator Incorrectly Canceling while Turning Right
Troubleshooting:
Pull out the rubber seal between the indicator stalk and the housing for the steering column and stalks.
If this fixes the problem that means that the rubber is pulling down the ...
- 181
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