Mazda 626 Station Wagon, Workshop Manual, Page: 109 / 577

ON-BOARD DIAGNOSTIC
DTCP1608
Except for GF4A-EL Models
DTC P1608 Malfunction in PCM circuit
DETECTION
CONDITION
• If the PCM receives abnormal signal from output devices, the PCM determines that PCM has
malfunction.
POSSIBLE
CAUSE
• Short power circuit to output device control circuit (PRC solenoid valve, purge solenoid valve, EGR
valve, and/or VICS solenoid valve).
• PCM malfunction
Diagnostic procedure
STEP
INSPECTION
ACTION
1 VERIFY RELATED REPAIR INFORMATION
AVAILABILITY
• Check for related Service Information
availability.
• Is any related Service Information available?
Yes Perform repair or diagnosis according to available
Service Information.
• If vehicle is not repaired, then go to next step.
No Go to next step.
2 INSPECT OUTPUT DEVICE CONTROL
CIRCUIT FOR SHORT TO POWER
• Disconnect output device (PRC solenoid
valve, purge solenoid valve, EGR valve,
and/or VICS solenoid valve) connectors.
• Measure voltage following connectors.
— PRC solenoid valve terminal B
(harness-side) and body ground
— Purge solenoid valve terminal B
(harness-side) and body ground
— EGR valve terminal A (harness-side) and
body ground
— EGR valve terminal B (harness-side) and
body ground
— EGR valve terminal E (harness-side) and
body ground
— EGR valve terminal F (harness-side) and
body ground
— VICS solenoid valve terminal B
(harness-side) and body ground
• Are voltages approx. 0 V?
Yes Go to next step
No Repair or replace harness, then go to next step.
3 VERIFY TROUBLESHOOTING OF DTC P1608
COMPLETED
• Make sure to reconnect all disconnected
connectors.
Yes Replace PCM, then go to next step.
• Clear DTC from PCM memory using NGS
tester.
• Turn ignition key to ON (Engine OFF)
• Is same DTC present?
No Go to next step.
4 VERIFY AFTER REPAIR PROCEDURE
• Perform “After Repair Procedure.”
(See F1 36 AFTER REPAIR PROCEDURE)
• Are any DTCs present?
Yes Go to applicable DTC inspection.
(See F1-37 DTC TABLE)
No Troubleshooting completed.
F1-88