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Discussion Starter · #1 ·
Greetings.

If there's one thing this forum is great at, it's motivating people to (part with large chunks of cash and) do their own mods. People like Swiss, Wesayso, Shadow, Corey, FJamming, etc., provide terrific step-by-steps and it's so helpful...I can't tell you how much I and others appreciate the attention to detail in your write-ups.

One area where I'm embarrassingly thick is automotive electronics. Living in the hinterlands of Vermont there are neither places I trust to take my vehicle to do this type of work, nor anyone I know who I could learn the fundamentals from (preferred).

That being the case, is there a real basic book/website on automotive electrical you might recommend? I'm less interested in theory -- though it's understood I need to learn some -- than I am about the practical requirements for adding accessories, testing, etc. I'm more than willing to put the lead time into things...hearing "Pops" and smelling the distinct odor of burning wires is a great motivator.

Many thx for your insights.

Bob
 

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Haynes manuals. They have terrific wiring diagrams in the back and thats pretty much everything you need to learn about auto wiring. The only thing I can think of thats important is tracing a wire, splicing, and checking for continuity/short with a simple $10 multimeter. Id recommend getting both digital and analog if you think about doing wiring a bit more than a few lights... and a really good automatic wire stripper.
 

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No problem! I usually buy the manuals for my old cars around the house and they are very helpful.... I dont think the FJ is out yet, so if you dont want to waste $15 and never use it, find someone with an older car (or if you have one), and buy the manual for that car... its a pretty nifty book to have around the shop. Unfortunately, it doesnt have the multimeter info.

But I can do my best to try to explain there usage here. The digital versions (DMM) are simple enough and are usually the only one I ever use (Ill get to the analog in a sec). Large dial on the front does everything you need in electrical... just turn the dial to begin. Typically, the DMM is divided into regions like a pie. It all depends on the manu, but each region is labeled with symbols. Set to V to measure volts (set to DC/AC for type of current). I start up high like 20k and move down the dial toward the 20 range... these are the multipliers on the reading... ie 5 on a 20k setting is 5000V, 5 on 20 setting is 5V. Set to the OHM symbol to measure resistance. Most DMM also have this audible setting as well, which is very handy for checking continuity. You can verify this by turning the OHM through the different ranges (same multipliers for voltage is used here... ie k =x1000, M=x1000000), and touching the two lead together, until you hear a sound... the sound means that the wire youre checking, or in this test, the two leads, have a continuous flow of electricity.
Finally, most DMM have a current setting to check the amps flowing. Be careful with this one cause too many amps (heck, even a 0.5A) is enough to give you a pretty good shock.

The same logic applies for the analog multimeter as well. Dial setting to measure volt, resistance, amps. The analog gauge is pretty useful for checking injectors (its good to see the needle fluctuate which most cheap DMMs do not do so well), and O2 sensors (also, need to check fluctuations).

Hope this helps! Like I said above, most wiring work is just identifying the wire (haynes manual or toyota manual, but that is very pricy), tracing it through the diagrams to see what it does, splicing into it if needed, and if its not working, checking for continuity or shorts.
 

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You can find the FJ wiring diagrams in the Full Factory service manual post.

Here is an ok YouTube vid about multimeters some bad attempts at humor but if you ignore that the information is pretty complete.
YouTube - How To Use A Multimeter

If you are a reader type this Multimeter Tutorial is a good set-by-step.

I highly recommend you get some hands on experience with someone who knows how to use a meter. You can get yourself is a lot of painful trouble really fast. Remember it's not the volts, it's the amperage that gets you.

Your FJ is only a 12v system but your battery has hundreds of potential amps. If you drop a wrench across both battery terminals you will melt metal so imagine what they would do to you.....

Not trying to scare you out of doing it yourself but trying to instill the need to respect the 'trons or they will bite - hard :bigthumb:
 

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and more reading:
Volume I - DC : All About Circuits

and more:
Introduction to DC Circuits

and more:
Multimeter - Wikipedia, the free encyclopedia

also... if you are truly a newbie (which there is no shame in that by any means) might I suggest you get one of these kits and "play" without risk:

Electricity Kits, Electronic kits

or

Electronics and Electricity Kits

this way you can play "doctor" all you want in the safety and comfort of your dining room table and get the fundamentals before heading out to the truck.
 

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Be careful poking around with a meter. Many vehicles, circuits, sensors, controls, LAN, matrix, computers, etc. are current and voltage sensing. Taking a wrong type of reading with the wrong type of meter can complete circuits and send signals that will mess things up. There are specialized meters that plug in various locations and there are manuals to help but they are expensive and pro oriented. It's all getting so complex and complicated. As others have said: read everything and read everything you can about the specific circuit you are investigating.
 

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Discussion Starter · #10 ·
Be careful poking around with a meter. Many vehicles, circuits, sensors, controls, LAN, matrix, computers, etc. are current and voltage sensing. Taking a wrong type of reading with the wrong type of meter can complete circuits and send signals that will mess things up. There are specialized meters that plug in various locations and there are manuals to help but they are expensive and pro oriented. It's all getting so complex and complicated. As others have said: read everything and read everything you can about the specific circuit you are investigating.
Thanks for the advice, DMAND. I'm looking to avoid trouble as much as I am to do the mods. Thx.
 

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In addition to what the others have said. Get a good analog multi-meter and a cheap Digital Volt Meter. Use the analog meter for everything (99%). The DVM only comes out when you need very specific measurements (i.e. +/-0.25v.. You'll learn a lot more about the way things work.. Good Luck..Ron
 

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In addition to what the others have said. Get a good analog multi-meter and a cheap Digital Volt Meter. Use the analog meter for everything (99%). The DVM only comes out when you need very specific measurements (i.e. +/-0.25v.. You'll learn a lot more about the way things work.. Good Luck..Ron
Ron, I disagree.

Digital = much higher internal resistance than analog. Analog has a typical internal resistance of 100K-500K Ohms. Digital has a typical resistance of 1-10M Ohms. Higher internal resistance = less current drawn from the source you're measuring. It used to be that the analog meters had the upper hand in current measurement, but for awhile now, they've been just as good or better.
 

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There's room for opinions.. Digital meters are great when you're working circuits and/or other electronics, but aren't necessary for general 12V Auto or 120V electrical work. It's a lot like watches...LOL.. All mine have an analog dial... I always trained technicians to learn a good analog multi-meter (Triplett 630NS) and use a DVM when the really needed it. It helped them IMO to learn electronic ranges/multipliers and to see trends. Just habit.. Cheers.. Ron

Ron, I disagree.

Digital = much higher internal resistance than analog. Analog has a typical internal resistance of 100K-500K Ohms. Digital has a typical resistance of 1-10M Ohms. Higher internal resistance = less current drawn from the source you're measuring. It used to be that the analog meters had the upper hand in current measurement, but for awhile now, they've been just as good or better.
 
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