DTC No. | Detecting Condition | Possible Cause | Related engine |
P1678 | ICM no responce, ICM message error | Communication line error (Open/Short etc.), Invalid message from ICM to ECM | δ2.7 |
PROBLEM VERIFICATION
Connect the hi-scan (pro) to data link connector.
Turn the ignition switch to ON and verify the DTC "P1678" is displayed.
Erase the DTC "P1678" with the hi-scan (pro) and then monitor again.
Is the same code displayed ?
▶ Problem is intermittent and ICM memory was not cleared
▶ Check engine control main relay
CHECK ENGINE CONTROL MAIN RELAY
Check that an operating noise can be heard from the engine control main relay(A).
Check for continuity between the terminals of main relay.
Is there continuity?
▶ Replace the engine control main relay.
▶ Check power voltage to SMARTRA
CHECK POWER VOLTAGE TO ICM
Turn the ignition switch to ON.
Measure the power input voltage of ICM between ICM harness connector terminal 1 and body ground.
Specification : approximately B+ (12V)
Is the voltage within the specification?
▶ Check for these problems ;
A blown ECU fusible link (20A) or sensor fuse (10A) in the engine compartment relay & fuse box.
An open or short in the wire between the engine control main relay and ICM.
▶ Check harness and connector between ICM and body ground
CHECK HARNESS AND CONNECTOR BETWEEN ICM AND BODY GROUND
Check for continuity between ICM harness connector(M23-1) terminal 8 and body ground.
Is there continuity ?
▶ Repair an open in the wire between the ICM and the body ground.
▶ Check harness and connector between ICM and ECM
CHECK HARNESS AND CONNECTOR BETWEEN ICM AND ECM
Check for continuity between ICM harness connector(M23-1) terminal 6 and ECM harness connector (C30-1) terminal 3.
Is there continuity ?
▶ Repair an open in the wire between the ICM and the ECM.
▶ If all the tests are OK, replace the ICM and recheck.
