Mazda 6 2002 Workshop Manual page 1013

ON-BOARD DIAGNOSTIC [IMMOBILIZER SYSTEM]
Note
• Perform the following if the security light stays on:
— If gasoline engine stalls, go to symptom troubleshooting NO.11 “ENGINE STALLS/QUITS, ENGINE
RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE, SURGES” in. (See
ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/
STUMBLE, SURGES.)
— If gasoline engine won’t start, go to symptom troubleshooting NO.6 “CRANKS NORMALLY BUT WILL
NOT START” in. (See
— If engine condition is normal but light stays on, inspect for continuity between the following wiring
harness and body ground: security light and PCM connector terminal 2W. Repair or replace the wiring
harness.
End Of Sie
DTC B1681
DTC B1681 Coil signal is not received.
• Defective coil
POSSIBLE
• Defective PCM
CAUSE
• Defective wiring harness
Diagnostic procedure
STEP
1 INSPECT POWER SUPPLY CIRCUIT OF COIL
• Disconnect coil connector.
• Turn ignition switch to ON position.
• Measure voltage at terminal D of coil
connector.
• Is voltage more than 10 V?
2 INSPECT WIRING HARNESS BETWEEN COIL
AND GROUND
• Turn ignition switch to OFF position.
• Inspect wiring harness between coil
connector terminal C and ground for
following.
— Short to power supply
— Open circuit
• Is wiring harness okay?
3 INSPECT COIL INPUT SIGNAL CIRCUIT
• Connect coil connector.
• Turn ignition switch to ON position.
• Measure voltage at terminal B of coil
connector.
• Is voltage more than 9 V?
4 INSPECT COIL INPUT SIGNAL CIRCUIT
• Turn ignition switch to OFF position.
• Disconnect coil connector.
• Measure resistance between coil connector
terminal B and ground.
• Is resistance more than 10 kilohms?
5 INSPECT COMMUNICATION CIRCUIT
(INPUT) FOR CONTINUITY
• Disconnect coil and PCM connectors.
• Is there continuity between coil connector
terminal B and PCM terminal 2T?
F–195 NO.6 CRANKS NORMALLY BUT WILL NOT
INSPECTION
Yes Go to net step.
No Repair wiring harness.
Yes Go to net step.
No Repair wiring harness.
Yes Go to Step 5.
No Go to net step.
Yes Go to Step 12.
No Repair wiring harness.
Yes Go to net step.
No Repair wirimg harness.
F–204 NO.11
START.)
A6E817067000W03
ACTION
T–161
T