Under the driver side dash there is a plug, it's called the OBD, or ALDL plug, depending on who you ask. Either way, put a jumper between pins A and B.
Ignore the writing around that pic. It's not related to this.
It can be a paper clip, or a short piece of wire, whatever. Put it in with the key in the off position, and then turn the key on. Now, watch your service engine light. It's going to blink out sequences of numbers. To start off, it's going to blink 1 time, then twice. this is a "12". It's going to do this 3 times for each code stored in the computer. Code 12, is always there, it's to let you know you are now in "diagnostic" mode. After the code 12 flashes out 3 times, get ready to start counting. Write down the sequences that it flashes out.
After you get all the codes, turn off the key and remove the jumper from the OBD plug. Then compare them to this chart, and see what you got. Post back and lets us know what you found.
Quote:
DTC - 12 No distributor reference pulse (diagnostic test active) DTC - 13 Oxygen sensor circuit open or no activity DTC - 13 Left bank O2 sensor circuit open or no activity DTC - 14 Engine coolant temp sensor error (high temp indicated) DTC - 15 Engine coolant temp sensor error (low temp indicated) DTC - 16 System voltage too low DTC - 17 Camshaft position sensor error DTC - 21 Throttle Position sensor error (signal high) DTC - 22 Throttle position sensor error (signal low) DTC - 23 Intake air temp sensor error (low temp indicated) DTC - 24 Vehicle speed sensor error (open circuit or no activity) DTC - 25 Intake air temp sensor error (high temp indicated) DTC - 28 Auto transmission range pressure switch error DTC - 31 Wastegate solenoid circuit error DTC - 32 EGR system failure DTC - 33 MAP sensor circuit error (signal high indicating low vacuum) DTC - 34 MAP sensor circuit error (signal low indicating high vacuum) DTC - 35 IAC problem or idle error DTC - 36 MAF sensor error DTC - 36 24x Crankshaft position sensor circuit error DTC - 37 TCC brake switch circuit error DTC - 39 Clutch switch circuit error DTC - 41 Ignition control error DTC - 41 MEM-CAL error DTC - 41 C³I Cam Sensor Signal error DTC - 42 Ignition bypass circuit error DTC - 43 Knock sensor error DTC - 44 Oxygen sensor error (lean condition indicated) DTC - 44 Left bank O2 sensor error (lean condition indicated) DTC - 45 Oxygen sensor error (rich condition indicated) DTC - 45 Left bank O2 sensor error (rich condition indicated) DTC - 46 Pass-Key II (VATS) system error - circuit out of freq range DTC - 51 PROM error DTC - 51 Incorrect MEM-CAL DTC - 52 Fuel cal-pak incorrect or missing DTC - 53 System voltage too high DTC - 54 Fuel pump circuit low voltage DTC - 55 ECM error DTC - 58 Trans fluid temp sensor circuit error (low voltage) DTC - 59 Trans fluid temp sensor circuit error (high voltage) DTC - 61 A/C system performance DTC - 63 Right bank O2 sensor circuit error DTC - 63 MAP sensor circuit signal voltage high (low vacuum indicated) DTC - 64 Right bank O2 sensor lean exhaust indicated DTC - 64 MAP sensor circuit signal voltage low (high vacuum indicated) DTC - 65 Right bank O2 sensor rich exhaust indicated DTC - 66 A/C pressure sensor circuit error (low pressure indicated) DTC - 67 A/C pressure sensor circuit error DTC - 68 A/C clutch relay circuit error (shorted to ground) DTC - 69 A/C clutch relay circuit error (open circuit indicated) DTC - 70 A/C pressure sensor circuit error (high pressure indicated) DTC - 71 A/C evaporator temp sensor circuit error (low temp indicated) DTC - 72 VSS signal circuit error DTC - 73 A/C evaporator temp sensor circuit error (high temp indicated) DTC - 75 Digital EGR solenoid #1 circuit error DTC - 76 Digital EGR solenoid #2 circuit error DTC - 77 Digital EGR solenoid #3 circuit error DTC - 79 Transmission fluid overtemp DTC - 80 Transmission component slipping DTC - 82 3x Crankshaft position sensor circuit error DTC - 85 PROM error DTC - 86 A/D error DTC - 87 EEPROM error (flash memory error) DTC - 90 TCC error DTC - 93 Transmission pressure control solenoid circuit error DTC - 96 Transmission system voltage low DTC - 98 Invalid PCM program DTC - 99 Invalid PCM program
