DTC P1618 - SERIAL PERIPHERAL INTERFACE (SPI) PCM INTERPROCESSOR COMMUNICATION ERROR Isuzu Trooper II

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If EEPROM calibration is latest version available, replace PCM. Retest system. If EEPROM calibration is not latest version, go to next step.
3. Reprogram PCM with latest available EEPROM calibration. Clear DTCs. If DTC P1618 resets, replace PCM. If DTC P1618 does not reset, repair is complete.

Diagnostic Aids

Check for poor connection, rubbed through wire insulation or a broken wire inside insulation each component. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, select DATA LIST, SPECIFIC ENGINE and DRIVERS CURRENT. When DRIVER MODULE 1 STATUS is displayed select YES. Using YES button, cycle through all driver circuits. If a fault was indicated in any of drivers circuits, go to step 4). If a fault was not indicated in any of drivers circuits, go to next step.
3. Using scan tool, select DRIVERS HISTORY. Using YES button, cycle through all driver circuits. If a fault was not indicated in any of drivers circuits, replace PCM. Retest system. If a fault was indicated in any of drivers circuits, check for an intermittent problem, see «DIAGNOSTIC AIDS»(ref-16268-S37617414152001010800000) .
4. Inspect fuse for faulty drivers circuit. If fuse is okay, go to step 6). If fuse was blown, go to next step.
5. Locate and repair short to ground between fuse and appropriate component. Replace fuse. Retest system.
6. Disconnect PCM connector of affected driver circuit. Inspect PCM and connector for damaged pins or terminals. Repair as necessary. If PCM and connector pins and terminals are okay, go to next step.
7. If none of drivers circuit faults were for CHECK ENGINE or CHECK TRANS, go to step 12). If any of drivers circuit faults were for CHECK ENGINE or CHECK TRANS, go to next step.
8. Turn ignition off. Disconnect PCM and turn ignition on. Using DVOM, measure voltage between affected light driver circuit at PCM harness connector and ground. If reading is about battery voltage, replace PCM. Retest system. If voltage is not as specified, go to next step.
9. Check for battery voltage to affected light driver circuit fuse. If voltage is as specified, go to next step. If voltage is not as specified, repair open circuit between ignition switch and fuse. Retest system.
10. Turn ignition off. Using DVOM, check for continuity between ground and affected driver terminal at PCM connector. If continuity exists, repair short to ground in affected driver circuit between affected component and PCM connector. Retest system. If continuity does not exist, go to next step.
11. Repair open in affected driver circuit between fuse and PCM connector. Retest system.
12. Reconnect PCM. Start engine and allow to idle. Using DVOM, backprobe affected terminal at PCM connector for battery voltage. If voltage is as specified, replace PCM. Retest system. If voltage is not as specified, go to next step.
13. Run engine at idle. Check for battery voltage to affected circuit fuse. If voltage is as specified, go to step 10). If voltage is not as specified, repair open circuit between ignition switch and fuse. Retest system.