27 votes

How can I disable my 2002 Ford Explorer so someone with a key can't start it?

If your friend is moving your vehicle without your consent and does so deliberately your friend is committing a crime. Vehicle theft. If you are asleep when this happens then consent was not given. I ...
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  • 3,812
26 votes

How can I disable my 2002 Ford Explorer so someone with a key can't start it?

I'll make it very simple for you, Dave. Just remove the relay highlighted, in yellow, from the diagram above. This goes to the starter.
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26 votes
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What is the most cost-efficient solution when door keys do not fit ignition?

Being a auto locksmith, I can 100% recommend that you have your door lock rekeyed to match your current ignition key. Cost will depend on location and if you remove the the lock yourself and take it ...
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  • 3,175
24 votes
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How does the car's ECU detect a misfire?

This comes directly from this web site: http://www.obdii.com/articles/Onboard_Diagnostics_Demystified.html What it says, is that early OBD-II systems could not detect misfires, but since then a few ...
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  • 9,276
20 votes

How can I disable my 2002 Ford Explorer so someone with a key can't start it?

Remove the publicly available key. Make one copy of the key for each person or household who needs to be able to move the car. Give a key to each person and have them sign an agreement that they ...
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  • 1,536
15 votes
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Car won't start, possibly due to ants in batteries

Ants are unlikely to be the source of your issue. Your battery is filled with sulfuric acid, and that is sufficiently strong enough to completely dissolve any ants that made their way into your ...
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12 votes

How does the car's ECU detect a misfire?

Engine misfire can also be detected by looking at the coil voltage just after the plug is fired. When the fuel/air mixture actually ignites there are lots of ions and radicals floating around. This ...
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  • 2,053
11 votes
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How exactly does running fuel-lean increase the temperature of ignition?

You have a qualitative description of what happens, but let's break it down to a smaller scale. When we talk about "temperature" of something, we are really talking about how fast the molecules are ...
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  • 273
10 votes
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Car won't start, lights and electronics flicker

This is usually the symptom of a dead battery. Has the car been sitting for a long time without being driven? Or did you leave the headlights or interior lights on? Try jump starting it (see owner's ...
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10 votes

2003 Honda Accord - Intermittent no start/no crank

From personal experience, I'd replaced ALOT of these working at the dealership. It wasn't just the accords either, it was quite a few Honda and Acuras that used the same design and power delivery ...
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  • 3,323
10 votes
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What can I do with an Inline Spark Tester?

First, think of the possible failure modes: Spark plug is clogged with carbon or has an isolation error - it conducts current, but doesn't generate sparks, because the current flows through the ...
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  • 6,997
10 votes
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What Could Cause Flash Over / Arcing to Reappear on New Plugs?

I think your problem is your plug wires. I think they are leaking along the boot and down to ground (earth). With this loss of energy, you'll also see the large carbon buildup on the business end, due ...
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9 votes

Corrosion on battery, won't start, making clicking noise, won't charge

Repeated clicking is a result of not enough power making it to the starter. Your battery either has a bad connection, or is too weak to turn the starter motor. Battery Connection Your problem may be ...
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9 votes
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Diesel engine timing?

Diesel engine timing is accomplished through the fuel injectors (they inject fuel at the proper times). Proper timing prevents pre-ignition because there's no fuel in the cylinder yet to ignite. Glow ...
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  • 4,900
9 votes

How can I disable my 2002 Ford Explorer so someone with a key can't start it?

As stated in other answers, you really need to get your new housemate to start listening to you. If he doesn't respect your property, do you really want him living with you? With regards to the ...
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8 votes
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Acceptable amount of slack in a timing chain with high mileage?

Referring to this website: If all is well and there is no slack in the timing chain then you will see about three to five degrees of "reverse motion" before the distributor begins to turn. To ...
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8 votes
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Distinguishing between mechanical and electrical failure in ignition diagnosis

If you are hearing the starter turn (typical starter whir), the most probable problem would be the one way clutch has gone out. It's the part of the starter with the teeth on it which engages the ...
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8 votes
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How Common are Voltage Drop Problems?

Voltage drop problems are very common in multi component, multi interface systems. For instance the starter motor has a cable that runs from the battery to the starter. The cable has ring terminals ...
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7 votes
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Single-cylinder engine - no camshaft position sensor?

In the dawn of fuel injection most cars used a simultaneous double fire system. During every crank shaft revolution the injectors spray half the fuel needed. This way half the fuel waits on top of the ...
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7 votes
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OBD II power when key not in ignition

Pin 16 on the ODB-II connector is specified as "Battery Power" or "Battery Positive". There will always be 12v power between pin 4 and 16. Note that pin 5 has "ground" in the description, but that ...
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7 votes
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97 Honda Accord won't start after head gasket replacement

You need Spark, Fuel, and Compression for an engine to run. Since this engine was just reassembled, there is a lot to question. Spark - rotor position - beware of caps where the points are not "...
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  • 8,393
7 votes

Key Doesn't come out of Town and Country

It sounds like your shifter may not be seating into park correctly. You may want to try moving it back and forth from gear into park (occasionally, with a slight amount of force; you don't want to ...
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7 votes

How exactly does running fuel-lean increase the temperature of ignition?

Funny you should ask this Max :) First lets make sure of our definition. Running an engine lean means changing the air / fuel ratio to have more air than is ideal (14.7:1 air to fuel). In my reading ...
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  • 9,276
7 votes

Distinguishing between mechanical and electrical failure in ignition diagnosis

If the picture you have attached is similar to the starter on you car, then the power to the starter motor is only delivered if the solenoid operates, so the solenoid must be working. However, the ...
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  • 19.9k
7 votes
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Do I Need to Ground the Spark Plug When Testing

Yes you should ground the spark plug. In your case the spark plug was close enough to the block to still jump the gap. If the plug was far enough away from metal nothing would have happened. On a ...
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  • 15.9k
7 votes
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How to check if spark plugs are firing? Coil-on plugs

You should have 2 coil packs on the back side of the engine near the throttle body. Wires run to individual cylinders. I don't know how easy it would be to find locally but you can use an inductance ...
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7 votes
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Effects of shutting off Nissan altima (or any car) while in drive

The transmission and its control systems will not be damaged by this practice. Safety could be compromised if the shifter is left in this position. The park lock will not be engaged so the vehicle ...
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  • 11.5k
7 votes
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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 ...
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6 votes

Unable to start engine - unable to unlock ignition key Citroen C3

When you turn the car off and remove the key, make sure the steering is not turned to one side. If you leave the car with the wheels turned you may load up the steering lock as the steering geometry ...
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6 votes
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What do you do with dielectric grease on spark plugs?

tl dr: You've hurt nothing by putting more than a little bit of grease in the boot ... don't worry about it. Dielectric grease serves two purposes: Prevent electrical leakage Keep the boot from ...
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