Loss Of Trouble Code Memory
- To check, disconnect TPS and idle engine until ENGINE CONTROL SYSTEM lamp illuminates. Code E022 should be stored, and kept in memory when ignition is turned off. If not, the ECM is faulty.
- Check for an electrical system interference caused by a defective relay, ECM driven solenoid, or switch. They can cause a sharp electrical surge. Normally, the problem will occur when the faulty component is operated.
- Check the vehicle's main power and ground connections.
- Check for non-Original Equipment (OE) or non-OE equivalent ignition parts such as ignition coils, distributor caps, distributor rotors, and spark plug wires. Some after market equipment may not meet GM specifications for transient suppression. Replace any suspect parts with OE or known good equivalent before proceeding with diagnoses.
- EST wires should be kept away from spark plug wires, distributor wires, distributor housing, ignition coil, and generator. Wire from ECM C/D connector (terminal D9, circuit 453) to distributor, should provide the ECM and distributor with a good common ground. The shield and drain wire provided for circuits 430 distributor reference and 453 EST ground should be intact. The Distributor Reference circuit 430, and EST ground circuit 453, will be susceptible to induced transient voltages if not shielded and routed as designed.
- Check for improper installation of electrical options, such as lights, 2-way radios, etc.