code reader OBD

If your vehicle has this style connector, but doesn't have these pins populated, you probably have a pre-OBDII vehicle. To add some confusion, even having the connector with the contacts shown above is not a guarantee of OBD II compliance. This style connector has been seen on some pre-1996 vehicles which were not OBD II compliant.

J1850 VPW--The connector should have metallic contacts in pins 2, 4, 5, and 16, but not 10.
ISO 9141-2--The connector should have metallic contacts in pins 4, 5, 7, 15, and 16.
J1850 PWM--The connector should have metallic contacts in pins 2, 4, 5, 10, and 16.

On 1996 and later vehicles, you can tell which protocol is used by examining the OBD II connector:

There are some variations among captive imports such as the Cadillac Catera, a German Opel derivative, which uses the European ISO 9141 protocol.

As a rule of thumb, GM cars and light trucks use SAE J1850 VPW (Variable Pulse Width Modulation). Chrysler products and all European and most Asian imports use ISO 9141 circuitry. Fords use SAE J1850 PWM (Pulse Width Modulation) communication patterns.

What Communications Protocol does my vehicle use

The big scanner consoles costing thousands of dollars include the decoding software and firmware for all three protocols in their units, making them universal. Less expensive units, for home or small shop use, are usually customized for a specific communications protocol. Be sure the scanner you are using suits the protocol of your car.

While the parameters, or readings, required by OBD II regulations are uniform, the auto manufacturers had some latitude in the communications protocol they used to transmit those readings to scanners. Naturally, each felt they had the one true way, so I have three different OBD II communications protocols in use.

The connector must be located within three feet of the driver and must not require any tools to be revealed. Look under the dash and behind ashtrays.

Two factors will show if your vehicle is definitely OBD II equipped:
1) There will be an OBD II connector as shown below, and
2) There will be a note on a sticker or nameplate under the hood: "OBD II compliant".

All cars and light trucks built and sold in the United States after January 1, 1996 were required to be OBD II equipped. In general, this means all 1996 model year cars and light trucks are compliant, even if built in late 1995.

Another highly useful application for the scan tool is purchasing used vehicles. Used vehicles can have all sorts of expensive mechanical or electrical problems. Since our reader is a portable device, the buyer, can connect the scan tool to the vehicle and in a few seconds determine if the vehicle has detected a problem. Remember, not all Diagnostic Trouble Codes illuminate the Check Engine light and a scan tool are the only way to obtain the information.

In area that requires a smog test, an illuminated Check Engine light fails the emission test, even if the repaired vehicle might otherwise pass inspection. This Tool extinguishes the Check Engine light.

Even if you don't repair the vehicle yourself, knowing the Diagnostic Trouble Code number before taking the vehicle in for repair the less likely you will be ripped off. Once the vehicle is repaired, the Diagnostic Trouble Code(s) can be erased and the Check Engine light extinguished using this scan tool.