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24 votes
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Why one should not leave fingerprints on bulbs and plugs?

Why is this a thing? For bulbs it is - spark plugs don't care. The problem with getting fingerprints on bulbs (specifically halogen-type bulbs) is actually the grease that gets left behind - the bulb ...
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  • 9,773
21 votes

Are oils from the skin a problem with turn signal bulbs?

The reason headlight bulbs are so sensitive is their high wattage, halogen design and therefore high heat. Almost all other bulbs in the car are low-wattage incandescent which makes them easier to ...
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17 votes

Park/marker lamps won't turn off

I pulled almost every fuse from the fuse block under the dash without any success, but now that it is dark outside I was able to see something I missed when it was day: when I put everything back ...
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13 votes
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Why are VW tail light bulbs listed as 12W / 5W?

If it is a 21W/5W bulb, then it has 2 filaments of different brightness. The 5W filament is for the side/tail light for night driving. The 21W filament is for bright illumination when you press the ...
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  • 20.9k
12 votes

Smart and effective ways to light up a garage without relying on power outlets?

Battery operated flashlights or worklights which share batteries with your cordless tools would be a good option. These will allow you to work on the car even with a dead or disconnected battery. ...
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11 votes
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How does a lightbulb with two filaments know which one to light up?

A typical 1157 taillight bulb looks like this: The filaments have a common connected to the shell and the other end of each goes to each the two terminals on the bottom of the bulb. The bayonet pins ...
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11 votes

Smart and effective ways to light up a garage without relying on power outlets?

There are a number of ways to do this, but the two that come immediately to mind are battery-powered LED work lights. (A quick internet search will turn up many). Two varieties might be of use/...
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8 votes

How do you test analogue electrical circuits?

To track down and troubleshoot electrical issues, you will almost certainly need a multimeter (also known as a Volt-Ohm meter) - digital ones are best, like the one illustrated below (from Wikipedia) ...
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8 votes
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How do you test analogue electrical circuits?

Tools Digital Multimiter Voltage, Resistance, continuity settings Automotive specific DMM's are typically the same device but may have a few extra features (Duty Cycle, RPM) CAUTION: Certain modes ...
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  • 496
8 votes
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What are reverse lights used for besides showing intention to reverse?

They are being used as approach lights. When someone unlocks their car with the remote the car turns on lights around the car. I think the idea is to light up the ground around the car for you to ...
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8 votes
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How to replace front fog light housing on a Corsa C 2005

EDIT: I have heard that you do not need to remove the entire wing panelling. I certainly didn't on my 2003 Opel Agila. Just remove the screws from the front of the wing on the bottom of the car. Makes ...
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  • 6,515
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 ...
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7 votes
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Motorbike has no power, but kick start works

From looking at your wiring diagram, you have clearly blown your main 15A fuse. This explains why nothing is working from the battery, but once the engine is running, your magneto is powering all the ...
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7 votes
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Is it Possible to Control Lights through OBD-II Port?

The short answer is: no - not without the manufacturer's diagnostic tools. The long answer is: maybe. Modern cars have most (if not all) exterior and interior lights controlled by the body control ...
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7 votes
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Headlight and dome light flickers

This is very common, and not a problem. When you are starting your car, the load on the battery is huge compared to when the engine is running, as the starter motor is having to turn the crankshaft ...
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  • 18.5k
7 votes

Can stock headlight wiring deal with 110 W bulbs?

0.85 mm² copper wires have a resistance of about 0.02 ohm/m, and when a current of about 10 A is driven through this wire, it dissipates about 2 W/m. This isn't soo much and should not ...
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  • 7,007
7 votes

Why one should not leave fingerprints on bulbs and plugs?

Fingerprints on spark plugs aren't a thing, the natural oils on your skin won't affect their operation. If, however, your fingers are covered in car grease or dirt when you handle the plugs then that ...
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  • 14.6k
6 votes
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Brake Lights Won't go On, Tail Lights Won't go Off

My friend faced a similar issue on his '03 Nissan Maxima. In his case we discovered that the brake pedal switch was not making any contact with the pedal linkage. The switch relies on contact with ...
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  • 39k
6 votes

headlights come on by themselves when car sitting in sun

Possible culprits: A bad headlight relay Have the relay tested or replaced. It could be that the switch for the main circuit is intermittently stuck-closed. A closed-circuit in the light switch or ...
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  • 39k
6 votes
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Brake lights and turn signals don't work (but head and tail lights do) on 1998 Ford Expedition

On the Expedition the hazard, lower brake lights, and turn signals all route through the multi-function switch. Gain access to the multi-function switch connector and back probe the light green wire ...
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  • 10.7k
6 votes

Smart and effective ways to light up a garage without relying on power outlets?

A "dead" car battery can still have more than enough juice to run things like LED lights, phone chargers, etc. - and lots of us have one kicking round the workshop we haven't got round to disposing of....
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  • 466
6 votes
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Can stock headlight wiring deal with 110 W bulbs?

TL;DR: You're on the edge, instead of pushing it, use the existing circuit to control a set of relays and supply the bulbs with a short run of larger wire. Use at least 3.3 mm² (12 AWG) wire, which ...
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  • 14.3k
5 votes
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Right side highbeam not working on on Mk2 Golf GTI - not fuse or bulb

Bulbs - Swap the bulbs, like the comment suggested, with the ones on the other side. If works switch back and get replacement. Fuse - Swap the fuse with another in the fuse box with the same rating. ...
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  • 66
5 votes

Mini Cooper 2003 - Identify rear indicator light wiring to install LED resistor

I'm going to answer this in a general way because for someone to tell you what the wires mean, they would need to follow this procedure, or have access to detailed wiring diagrams for your car. You'...
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  • 13.2k
5 votes

Troubleshooting Trailer Lights

It sounds like you have a ground issue. When the running lights are on they are actually grounding through the brake lights. When you apply the brakes it cuts off the ground and the lights go out. The ...
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  • 15.9k
5 votes

Vauxhall Zafira rear lights not working

Because stop / tail lights are so important, manufacturers will occasionally split the circuit so that they have a fuse for each side of the car. That way, if the fuse blows, you don't loose all ...
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5 votes
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What is the formula to determine a relay for aftermarket lights?

You need to know up front what the Amperage of the lights are in the first place and work from there. In the case of the light in the link is has a 72W draw on it. @ 12vdc, this calculates to 6Amps ...
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5 votes
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What type of crimping pliers do I need for these connectors

I believe crimping pliers for weather pack, metri-pack, or molex connectors will work. IWISS makes a tool just for those types of connectors. Alternatively, Paladin makes a crimping tool with die ...
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5 votes

Car Bulbs: T10 W5W 501 what do numbers and letters actually mean?

T10 Refers to tubular glass, 10 mm diameter, according to this forum post. W5W The W5W defines the bulb "category", which is the standardized filament lamp design, as explained in ECE Regulation 37....
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  • 39k
5 votes

What's this inside my gear shift?

I've seen this before. The bulb assembly usually fits into the gear indicator mechanism in a similar way that brake lights fit into brake light assemblies. That is, usually the bulb socket has a ...
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