ELECTRONIC DRAINS WHICH SHUT OFF WHEN BATTERY CABLE IS DISCONNECTED
- Perform battery drain test. See «BATTERY DRAIN TEST»(ref-139334-S40275708612002043000000) . Ensure all doors are closed and accessories are off. Without starting engine, turn ignition switch on for a moment, and then turn ignition off. Wait a few minutes for illuminated entry lamps to turn off (if equipped).
- Connect ammeter between negative battery cable and negative battery post. Disconnect negative battery cable from negative battery post, without breaking the ammeter connection to prevent modules from resetting. Read amperage draw.
- Amperage draw should be less than 50 milliamps. If current draw exceeds 50 milliamps, remove fuses from battery/central junction box one at a time to locate problem circuit. Repair appropriate circuits as necessary. See POWER DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
PCM Reset Procedure
After a PCM reset procedure has been performed, the following conditions will be met
- All DTCs will be cleared from PCM memory.
- All freeze frame data will be cleared from PCM memory.
- Diagnostic monitoring results will be cleared from PCM memory.
- OBD-II system monitor status will reset.
- DTC P1000 will be set in PCM memory until all OBD-II system monitors or components have been tested to satisfy OBD-II drive cycle without any faults occurring. To clear DTC P1000, perform DRIVE CYCLE PROCEDURE under DIAGNOSTIC MONITORS in appropriate SELF-DIAGNOSTICS in ENGINE PERFORMANCE. Ensure OBD-II DRIVE CYCLE PROCEDURE is performed to verify repair.
To perform PCM reset using scan tool, follow scan tool manufacturer's operating instructions. If after clearing DTCs a concern has not been corrected, or a fault is still present, a hard code will immediately be reset in PCM memory.
Keep Alive Random Access Memory Reset Procedure
| CAUTION | When battery is disconnected, vehicle computer may lose memory data. Driveability concerns may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting the battery. |
- Resetting Keep Alive Random Access Memory (RAM) will return PCM memory to its default setting. Adaptive learning contents such as idle and fuel trim are included. PCM reset procedure is part of keep alive RAM reset. See «PCM RESET PROCEDURE»(ref-139334-S18954870432004080400000) . If an error message is received or scan tool is unable to perform keep alive RAM reset procedure, disconnect negative battery terminal for a minimum for 5 minutes, then go to next step. If using Worldwide Diagnostic System (WDS) or New Generation Star (NGS) scan tool, turn ignition switch to ON position. Select ACTIVE COMMAND MODES, then select RESET KEEP ALIVE MEMORY. Go to next step.
- After keep alive RAM has been reset, engine must idle for 15 minutes to learn new idle air trim values. Idle quality will improve as strategy adapts. Adaptation occurs in 4 separate modes. See «IDLE AIR TRIM LEARNING MODES»(ref-139334-S34828061842004080400000) table. IDLE AIR TRIM LEARNING MODES Transmission Gear Selector Position A/C Mode Neutral On Neutral Off Drive On Drive Off