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TTs - OBDI Code Reading

"Ahh... Not another Check Engine Light..."

The car's computer, known as the Engine Control Unit (ECU), runs the car but also watches critical values and tables while the car is running.  This system is known as the On-Board Diagnostic (OBD) system.  Version 1.0, as known as OBDI, came out back in the late 1980's and it helps to lower emissions and maintain car drivability.  Version 2.0, or as refered to OBDII, was installed and standardized by the government for the 1996 model year, to have better programming to lower emissions again and to have the system be more strict on failing parts / values.

Read / Obtain Diagnostic Trouble Codes:
1.)  Locate the OBD serial port, on the dash above the cigarette lighter and below the heating / venting / air conditioning controls.  Gently remove the dash trim piece covering up the port.
 
2.) With the ignition key ON (but not running), use a jumper wire to connect terminals #4 [ground] & #15 [L-wire] for 2.5 seconds and remove the jumper wire.

3.) After one blink of the Check Engine Light (CEL), the first four digit code will be displayed. The number of blinks coresponds with the numerical value. Note: if the blink code of 4-4-4-4 appears, no malfunctions have been stored in the OBD system.

4.) Once the first DTC has been displayed, reconnect the wire for 2.5 seconds and then remove the wire once again. A new code (if stored) will flash; repeat connecting wire if the same code does not appear until then.

5.) Turn the ignition off.  Make repairs accordingly given by the OBDI blink codes.

Erase Diagnostic Trouble Codes (DTCs):
1.)  With the ignition key OFF, connect the jumper wire or adaptor to the diagnostic terminals.
 
2.)  Turn key to the ON position, wait at least 5 seconds and then disconnect the wire / adaptor.
 
3.)  Reconnect the jumper wire / adaptor for 2.5 seconds and then remove it.  The first DTC (if present) will be displayed.
 
4.)  Repeat step 3 until no more codes are displayed (DTC 4-4-4-4 is shown).
 
5.)  Reconnect jumper wire / adaptor for 2.5 seconds and remove it.  THe DTC memory is now erased; turn ignition OFF.

- Average Time:  5 minutes
- Scheduled Maintenance: when Check Engine Light is on
- Price of Materials:  jumper wire ~ $1.00
- Written by Bentley Publications
- Edited by Erik Melander

cellight.jpg

The Check Engine Light (CEL), shown above, will light up on the instrument panel if OBD system notices a problem with the vehicle's emission controls or drivability.  The issue should be taken care of promptly, but it is acceptable to drive the vehicle when needed.  If the CEL begins to flash, that means there is a serious problem with the powertrain and the problem should be resolved as soon as possible.  If the vehicle is driven often with a flashing CEL, damage will be done to the catalytic convertor and emissions system.

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