Hi my friends . I would like to thank everyone for the help you all have given to me. As before My 1994 Vette will not start, I tryed pulling the codes but the computer would not send any info to the tester ( this tester is my friends and he is the hear man at a ford dealedship the tester is a $ 6000.00 tester and he knowes's how to use it ). It was pluged in corectly but it would not talk to the tester at all. Is there anyone out there that could tell me why? I can't get the codes I need to tell me for sure that it is a bad opti or not . Still will not start, I don't want to take all that stuff off without knowing that is the problem but now I can't get the obd 1 output to comunicate with the tester. Any ideas? This thing is driveing me nuts. I thank you all.
Health, Love and Happiness always.
Your friend, Teddy.

 

If you are really asking about a 1994, that is a C4. This is C6 Tech. You need to re-post in the C4 Tech Forum.

 

If you have a 94 C4,,, it is OBD1 and does not need the GM Tech 2. It uses the TECH1 BUT,,,,,,, You can read your own DTCs

All you need to do is use a paper clip and short PINS "A" & "B" together in the ALDL connector under the drivers dash

The DTCS will display in the CHECK ENGINE LIGHT as a set of FLASHES

Google "Reading GM OBD1 Codes" and you will be able to see some U tube demostrations on how to read the DTCs

Here is the complete list of OBD1 DTCs


GM OBD-1 Diagnostic Trouble Codes

For 1995-previous model year EFI-equipped GM vehicles. NOTE: Some codes not supported on all models, consult your specific vehicle's service manual for the correct trouble code list and description for your application.

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 - 26 Quad Driver Module (QDM A) error

DTC - 28 Auto transmission range pressure switch error

DTC - 31 Wastegate solenoid circuit error

DTC - 31 Gear Position Switch (PRNDL) 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 - 36 4T60-E Shifting Error

DTC - 37 TCC brake switch circuit error

DTC - 38 TCC brake switch circuit error

DTC - 39 Clutch switch circuit error

DTC - 39 TCC 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 - 47 UART (serial data) circuit error

DTC - 51 PROM error

DTC - 51 Incorrect MEM-CAL

DTC - 52 Fuel cal-pak incorrect or missing

DTC - 53 System voltage too high

DTC - 53 Digital EGR Valve solenoid 1 error

DTC - 54 Fuel pump circuit low voltage

DTC - 54 Digital EGR Valve solenoid 2 error

DTC - 55 ECM error

DTC - 55 Digital EGR Valve solenoid 3 error

DTC - 56 Quad Driver Module (QDM B) error

DTC - 57 Boost Control error

DTC - 58 Trans fluid temp sensor circuit error (low voltage)

DTC - 58 VATS system error

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 - 69 A/C high pressure switch error

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