Rick's Free Auto Repair Advice

Free wiring diagrams

Where can I get free wiring diagrams?

Everyday I see posts from people looking for a free wiring diagrams or free shop manuals.

Sorry guys, free wiring diagrams don’t exist or at least not in the format you want.

Even when I see someone answer the poster’s question with a link, the diagram is usually the wrong one Face it, no car maker is going to give away free repair information. You’ll find some free diagrams on my site. But that’s only because I’ve taken the time to redraw them to avoid copyright infringement.

The next issue is that there’s really no such thing as a single wiring diagram for certain year, make, and model. Looking for a free wiring diagram for a headlight? Does it have a light sensor to automatically turn the lights on? The basic model may not have that feature even though it’s standard on the top model. The wiring will be different for both. Next, does the vehicle have daytime running lights? Again, two different diagrams.

Want a diagram for sensors? The issue gets even more complicated. Now you need the engine code and sometimes even the manufacturing date. So you see there are literally hundreds of combinations for a single body style. That’s why OEM shop manuals run well over 1,000 pages.

Here’s an even more important reason to get good repair information

Why spend your time an energy tracking down a wiring problem when somebody else may have already found the cause? That’s why car makers publish Technical Service Bulletins (TSBs)–to let all the dealers know when they discover a pattern of failures. A TSB isn’t a recall. If a car maker discovers that a certain wiring harness is rubbing or chaffing and causing an electrical problem in certain makes and models, they’ll publish a TSB. That save the dealer a lot of time.

Having a current list of TSBs can save you a LOT of money and time too. Every time I volunteer in auto forms I read questions from readers who’ve spend hundreds of dollars replacing parts that were perfectly fine. I can usually find a TSB that nails the problem. If the DIYer had only spent a few bucks on Alldata or Eautorepair, they could have saved hundreds. For example, Ford Windstar vans are known for lighting the Check Engine light for a “lean” code. If you didn’t have the TSB to know that they are having a problem with intake manifold gaskets, you could spend a fortune replacing the oxygen sensors, spark plugs, and other ignition parts.

Another example of this is the Ford Expedition. The V-8 engine on this vehicle can develop a misfire and set off the check engine light. The usual first step in diagnosing a misfire is to examine the spark plugs or the spark plug wires. In this case it turns out that the ignition coil are failing at a high rate. If your technician doesn’t refer to the TSB’s they will replace the plugs, wires, and coil. But what caused the coil to fail? It turns out that a heater hose connection directly above the coil is prone to leaking. That’s what shorted out the coil in the first place. If you replace those ignition parts without fixing the heater hose leak, you’ll be doing this repair all over again.

It’s gotten to the point where no professional technician will even begin to diagnose a problem with out first consulting the current TSB’s. The key word here is “professional” technician. If you’re not a do it yourselfer and you want advice about getting your car fixed, make sure you explicitly tell the shop to check the current TSBs before you authorize them to begin any diagnosis.

Where can you find a list of TSB’s for your vehicle? Well, you can go to your dealer and ask if you can browse their collection. Just don’t expect a joyous reception for that idea. Nope, the sad truth is that you’re going to have to pay. Aside from going to the manufacturer’s web site and paying a small fortune for limited information, the best place to look is either eautorepair.net or an online shop manual at your public library.


© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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