Rick's Free Auto Repair Advice

How to get a car wiring diagram

Find a car wiring diagram

Every day in every auto repair forum I see people ask for a car wiring diagram. It’s really a crazy request. It shows they don’t have a clue how car makers group their wiring diagrams and it assumes that the wiring diagrams are the same for each engine in that model year. I’ll give you some examples of exactly what’s involved in finding the right car wiring diagram and why your request is so out of line.

Car Wiring diagrams are grouped by system

Let’s take a look a screen shot from a professional shop manual like Mitchel’s OnDemand. I’ve entered a 2000 Toyota Camry as the year, make and model we’re working on. Then I selected the ELECTRICAL category and clicked on the Wiring Diagrams sub-category. Now I can choose the car wiring diagrams based on which system I want to work on.

car wiring diagrams

Choose year, make, model. Then choose ELECTRICAL. Then the Wiring Diagrams sub category. THEN choose the system you’re working on.

There are 27 different system categories to choose from. Within each system category, there are multiple sub-categories. Let’s say you want the wiring diagram for a MAF sensor. Since a MAF sensor is part of the engine performance category, we’ll select that.

Wiring diagram for sensors

Oh wait, look at all these sub categories! Now we have to choose the EXACT engine we’re working on. Is it a 2.2 liter or a 3.0 liter? Is it powered by gasoline or compressed natural gas. Does it have an immobilizer system (anti-theft) or did it ship without an immobilizer system? Is it a 3.0 liter with California emissions or without?

car wiring diagram

Want to find a car wiring diagram for a sensor? Look at all these choices

Got that? Made your choice? Now you’ve got three or four more pages to look through to find the MAF sensor. So you see, there are over 17 pages of car wiring diagrams just dealing with engine performance sensors for this one year, make, model. Ask for the wiring diagram for a MAF sensor on a 2000 Toyota Camry, without any other information and there is NO way anybody can help you.

Wiring diagram for exterior lights

Let’s try this again. This time let’s say you’ve asked for a wiring diagram for your backup lights. Is it a 2.2 liter or 3.0 liter? Is it powered by gasoline or compressed natural gas?

backup lights wiring diagram

You’ve even got choices when it comes to something as simple as a wiring diagram for backup lights

Best place to find wiring diagrams

Based on all the different wiring diagrams shown here, 2.2 liter with and without CNG, with and without an immobilizer, or a 3.0 liter with or without California emissions, you’re simply not going to find the RIGHT wiring diagram for FREE online. You may find a diagram, but is it the right one?

Here are your choices:

Get free wiring diagrams at the library

Call your local library and ask if they offer online access to auto repair manuals. Many libraries DO offer that service and it’s free. But there’s caveat; you must access the services from the library, not your home. That means you should bring money with you to print out the diagrams on their printers.

Subscribe to an online professional repair manual to get a car wiring diagram

Alldatadiy.com and eautrepair.net are the two best in my opinion. Which is better? Well, Alldatadiy uses factory diagrams which are usually more accurate but much harder to read. They include wire color abbreviations and connector identifications most people don’t understand. So you have to refer to another guide to deciper the color codes and use another guide to find the location of the part.

Eautorepair.net redraws all manufacturer wiring diagrams so they make more sense. They include the wire colors AND the locations of the parts–right on the same diagram. So you don’t have to find another guide to decipher colors or find the location. I like eautorepair.net best.

Factory manuals with factory wiring diagrams

Factory manuals are the best in the business. But they’re also the most expensive. You can buy them in print or access them online. Most car makers offer a daily, monthly or yearly rate to access their online services. To check out genuine factory manuals, click here.

©, 2017 Rick Muscoplat

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