An Oldsmobile Aurora mostly uses the Environmental Protection Agency's standardized On-Board Diagnostics. OBD-II coding is not the absolute answer for engine problems, but it is a valuable tool for one good reason. The Aurora's engine is a complex machine, and the OBD-II system can provide focal points. This cuts out a lot of useless searching, and it effectively gives you practical places to start investigating. If you own an Oldsmobile Aurora manufactured in 1995, you may have to use General Motors' older diagnostic system.
Connect an OBD-II code reader to the Aurora's computer outlet. This port is referred to as a data link connector, and it can be found on the driver's side of the Aurora, beneath the dashboard, between the gas pedal and the far left kick panel.
Start the Aurora's electrical system. Some code readers may also need the engine up and running.
Look at your code reader. If your brand of code reader does not feature auto-activation and auto-retrieval functions, you will have to switch your reader on and key in a retrieval command. Reader button displays differ by brand, and for the exact instructions, defer to your code reader's manual.
Find the OBD-II code's meanings. You can locate definitions in your reader's manual, but you will likely only find the generic OBD-II codes there. General Motors has created its own supplemental codes, and those will need to be located online.
Make a list of codes the reader extracted. Look at the reader and determine what is "trouble" and what is "pending." If engine malfunctions repeat often, the OBD-II system will classify them as "trouble." This also activates the Aurora's check engine light. "Pending" codes happen less often, but they could easily trend toward "trouble." Give the trouble codes priority, but also investigate pending codes.
Open the Aurora's engine compartment. Locate engine parts that correspond with the codes on your list and investigate. Draw a line through codes you eliminate from consideration. Place a check mark next to the ones that merit deeper investigation.
Look beneath the dashboard and find the assembly line data link. The ALDL will be directly beneath the steering wheel.
Connect the "B" and "A" ports on the ALDL with jumper wire. Both ports are next to each other and are on the ALDL's top row. Both are the last two on the right side.
Turn the Aurora's engine on and count how many times the check engine flashes at you. This will be in a code that you will have to decipher. For instance, GM flash code 19 will be relayed with one long flash, a quick pause, and nine brief flashes. Code 23 would be two long flashes, a quick pause, and three brief flashes. Write down every code number conveyed.
Look up General Motor's flash codes online. The Aurora's manual will not contain these codes, and the Internet is the cheapest option available. Copy out the coding explanations you find next to numbers you jotted down.
Open the Aurora's engine compartment and investigate. Examine all the places that correspond with your code list.
