Finding Your Signal Wire

You May Not Need a Diagram

The following document has the wire colors for the oxygen sensor for many models of car. See Oxygen Sensor Wire Colors for more information.  Be sure to magnify the image by clicking in it, for clear reading.Once you have identified the signal wire on the sensor, then go back to where the sensor wires plug into the vehicles wiring harness.  You need to do this to find out what colors are used for the same wire in the vehicle's wiring.

Repair Manuals

When I buy a new or used car, I always buy the Haynes manual for it. Included in the manual is the wiring diagrams and the color codes for all of the sensors. I assume that Chilton's, Clymer and other similar manuals will be similar. But I have always found Haynes to be the most informative. These manuals cost $20, and I have always found this to be money well spent. They can usually be gotten from your local auto parts store, or from their online site: HaynesOnline. There are a few makes and models that they don't cover, but they have a manual for most vehicles sold in the US. If you're on a budget, you might try finding your manual on Ebay, or even see if your local library has it.

AutoZone

Next, see if you can find your diagrams for free at AutoZone. AutoZone posts wiring diagrams for many cars and trucks for free. It also has a vast amount of repair information, including diagrams of part locations, detailed instructions, etc. If you don't have a repair manual for your car, you can just about get by with this all by itself. However, not all cars are covered by this service. You'll just have to look and see if yours is.

To see what they have for your vehicle, follow this link: AutoZone Select Vehicle Page. Then select your year and make/model of car. I went ahead and registered, but I think you get all of the same resources without registering. However, by registering, I have saved my car's information, so when I login again, I can just select my car without having to re-navigate the car selection.

I had a hard time finding the wiring diagrams, so to specifically find those, do the following:

• Locate your car, year, make and model.
• Select "Repair Info" at the left side of the screen.
• Then select, "Vehicle Repair Guides" -> Chassis Electrical -> Wiring Diagrams
  

I was able to locate my ECU diagram, my oxygen sensor signal wires, all of my other sensors etc. Also, I was able to look up my MAP (Manifold Absolute Pressure) sensor. It told me which kind I had (DC voltage or frequency type), and even told me what resistances = what pressure in the ECU. The same goes for it's entry on the CTS (Coolant Temperature Sensor). It told me what temperature = what resistance from the sensor. This will help you enormously if you need to do adjustments to any other sensors.

Mitchell's

If the above resources weren't able to help you, then you can get your wiring diagrams from Mitchell's Online Repair Manual web site. The way to do this is to sign up for their 1 week subscription, which costs $10.49 (at the date of this writing). This is a one time payment, and entitles you to access for 1 week. You'll then want to copy the wiring diagrams and save them for your future reference.

Note: Unfortunately, this service is only for models that are sold in the United States. Models that are not sold here are not covered by this service. This includes domestic manufacturers, that make models sold only in overseas markets, but not in the U.S. If you are aware of a similar service that supplies diagrams for foreign makes and models, please email me, and I'll update this article with the information.

Once you've logged in, you'll do the following steps:

1. Go to Mitchell's Web Site.
2. Press their "Subscribe" button, then select your vehicle, and finally pay them to join their service. You only need to sign up for 1 week.
3. Press the "Repair" button.
4. Select "Wiring Diagrams"
5. Select "System Wiring Diagrams"
6. Go down until you find the section "Engine Performance Circuits"
7. Copy these diagrams. All of your sensors will be included in this section.
8. If you want any other diagrams, copy and save them as well.

Copying the Images

The images can be copied with just about any image processor, even Microsoft's "Paint" program. I'll describe the steps below for several image programs, including Paint.

If you use these images directly in your browser, you'll need to blow them up. You'll see a link at the top "Click Here for full size versions". However, you don't need to blow them up when copying the images. They'll copy full size by using the following instructions. In each case, in the instructions below, you're going to open an image editing program, and then drag the image from your browser and drop it on the image editor.

In case you don't know how to drag and drop, you put your muse over the diagram in your web browser and push down the left mouse button. Hold the left mouse button down and move your mouse over your image editing program. Then release the mouse button. The full sized image will be copied into your image processor. Below are the specific steps for 2 programs:

Microsoft Paint

You must do each file one at a time. You can't drag a 2nd image into the Paint program until the first one has been resized and saved. For each diagram image, do the following steps:

1. Image->Resize - Set the Horizontal and Vertical sizes to 50%.
2. Save As-> - Then select type "jpg" as the file type.

Paint.net

This is a free program that you can download and install. It was originally written at the University of Washington, and is still maintained by some of the original authors. It is completely free, and it is much better than Microsoft Paint. To get the free download, go to http://www.getpaint.net/. Once its installed, open the program and do the following steps:

1. Drag each image you want to save onto the Paint.net program window. You can drag all of the images into Paint.net, and it will create a new file for each image. You don't have to save each image before dragging in another one.
2. For each image, do the following steps:
1. Image-Resize...->By percentage->50%.
2. File->Save As..->Save as type: jpeg-> - Use 50% quality setting.