1989-1990 VNT fault codes are courtesy of another website;
I have not verified if they are accurate or not.
 Code 11  Ignition Reference Signal (No distributor reference during cranking)
 Code 12  Memory Standby power recently lost
 Code 13  Problem in MAP Sensor pneumatic system
 Code 14  Problem in MAP Sensor electrical circuit
 Code 15  Problem in distance sensor circuit
 Code 16  Loss of battery voltage sense
 Code 17  Engine running too cool
 Code 21  Problem in Oxygen Sensor circuit
 Code 22  Problem in Coolant Temperature circuit
 Code 23  Problem in Charge Temperature circuit
 Code 24  Problem in Throttle position Sensor circuit
 Code 25  Problem in AIS (Automatic Idle Speed) driver circuit
 Code 26  Peak injector current has not been reached
 Code 27  Problem in Fuel circuit in logic module
 Code 28  Problem in Canister Purge Solenoid circuit
 Code 29  Surge Valve Solenoid
 Code 31  Problem in Canister Purge Solenoid circuit
 Code 32  Surge Valve Solenoid
 Code 33  Problem in Air Conditioning Wide Open Throttle cut out relay driver circuit
 Code 34  Problem in Speed Control Driver circuit
 Code 35  Problem in Fan Control Relay driver circuit
 Code 36  VNT Solenoid # 3 circuit failure
 Code 37  Problem in Barometric Read Solenoid circuit
 Code 41  Charging System excess or no alternator field current
 Code 42  Problem in Auto Shutdown Relay driver
 Code 43  Problem in Spark Interface Circuit
 Code 44  Battery Temperature out of range or Fusible link J2 failure
 Code 46  Battery voltage too high
 Code 47  Battery voltage too low
 Code 51  Baro Reading out of Range
 Code 52  Oxygen Feedback System
 Code 53  Internal Logic Module Problem
 Code 54  Problem in Distributor sync circuit
 Code 55  Indicates End of diagnostic codes
 Code 61  Baro Read Circuit Failure
 Code 62  Internal Controller Failure
 Code 63  Internal Controller Failure
 Code 64  VNT Solenoid # 1 Failure
 Code 65  VNT Solenoid # 2 Failure
 Code 67  Problem in Overboost shutoff system (VNT Overboost Condition)
 Code 76  Ballast Bypass Relay failure
 Code 77  Speed Control Circuit failure 

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