What do d+ and d- mean?

[MacJaxson]

d+ is the manual upshift function for automatic transmission models, and d- is the manual downshift function for automatic transmission models. When an automatic transmission model is switched to manual mode, the driver can manually shift gears based on the vehicle's driving conditions, enhancing driving pleasure and improving safety in special road conditions. Relevant information about automatic transmission models is as follows: 1. The manual mode of automatic transmission models can be unused: It is perfectly fine not to use the manual mode of automatic transmission models, as it is optional. When used, the driver can manually shift gears to increase driving pleasure and improve the vehicle's ability to handle difficult road conditions. 2. Driving automatic transmission models is very convenient: Since these vehicles lack a clutch pedal, driving only requires the use of the D gear, with no need for other gears. Simply steering the vehicle is sufficient for driving.

[McKimberly]

I've been driving for over a decade, and D+ and D- mainly appear in a car's alternator system. D+ is the alternator's excitation terminal, acting like a small switch that provides current to the alternator for proper power generation; D- usually refers to the ground terminal, connected to the negative side of the battery, completing the electrical circuit. These two terminals are crucial—if D+ has poor contact or breaks, the alternator might stop charging, making the car hard to start and damaging the battery; a loose D- can cause poor grounding, leading to unstable voltage, flickering headlights, or AC failure. When I was younger, I once had a corroded D+ wire, causing the alternator to stop working and leaving me stranded on the road—a tough lesson. During regular maintenance, remember to check wiring harnesses for damage or looseness, keep them clean and rust-free, and don’t wait until problems arise. These small details add up and keep your car running smoothly.

[VonLilah]

For someone like me who's a bit interested in automotive electrical systems, D+ and D- are the core components of generator control. D+, as the excitation input terminal, provides current through the voltage regulator, precisely maintaining the output voltage around 14 volts to ensure proper battery charging and stable operation of the lights; D- likely refers to the ground terminal or battery negative terminal, responsible for the current return path. When the system is functioning normally, the vehicle runs smoothly. However, if D+ experiences a short circuit or open circuit, the generator stops producing electricity; poor grounding due to corrosion on D- can easily cause voltage fluctuations that burn out bulbs or trigger other circuit failures. It's recommended to regularly check the voltage at the D+ terminal with a multimeter and clean and maintain the wire connections as needed. Understanding these aspects not only helps prevent the car from stalling midway but also assists in avoiding hazards during DIY repairs, making car maintenance easier.

[McJosie]

Simply put, D+ and D- are the two terminals on the generator. D+ is the excitation terminal, responsible for controlling the current to make the generator operate and generate electricity; D- is the ground terminal, connected to the negative terminal of the battery. This combination ensures the smooth operation of the vehicle's charging system. If it fails, issues like insufficient battery charging making the car hard to start, or dim lights and weak air conditioning may occur. The checking method is quite simple: after starting the engine, measure the battery voltage, which should rise to 13-14 volts. If there's a problem, further inspect the terminal connections. Don't delay on small issues; early handling saves money and hassle.

[DelRosalie]

Back in the days driving that old van, a loose D+ terminal caused the alternator to fail, leaving me stranded roadside at night. That experience taught me the D+ terminal controls excitation current to regulate voltage in the alternator, while the D- terminal acts like a ground to maintain current return. When either fails, the charging system collapses - lights flicker, battery drains fast, and electronics get vulnerable. Now I make it routine to inspect terminals and connections during maintenance, applying anti-corrosion grease to prolong parts lifespan by a decade. Rookies shouldn't take this lightly - prevention beats repair every time.