What Does P1679 Mean?
The Malfunction Indicator Lamp (MIL) control circuit for the drive-by-wire system has an open circuit condition. The ECM cannot communicate MIL commands to the instrument cluster.
Common Causes
40%
Broken or disconnected wire in harness between ECM and instrument cluster
25%
Corroded or loose connector terminals at ECM or instrument cluster
20%
Failed instrument cluster MIL circuit board or LED driver
10%
Failed ECM internal MIL driver circuit (open condition)
5%
Blown fuse in MIL or instrument cluster power circuit
Diagnostic Steps
1
Step 1: Check all relevant fuses for instrument cluster and ECM circuits
2
Step 2: Inspect and test continuity of MIL control wire from ECM to instrument cluster (should have <5 ohms resistance)
3
Step 3: Check for proper ground connections at instrument cluster and ECM
4
Step 4: Test ECM connector pins for proper seating and corrosion, verify pin tension
5
Step 5: Command MIL on with scan tool and measure voltage at instrument cluster connector (should see switching voltage)
Estimated Repair Cost
$100 - $750
Parts + labor, varies by vehicle and location
The Malfunction Indicator Lamp (MIL) control circuit for the drive-by-wire system has an open circuit condition. The ECM cannot communicate MIL commands to the instrument cluster.
The most common cause of P1679 (Drive By Wire MIL Circuit Open Circuit) is: Broken or disconnected wire in harness between ECM and instrument cluster
Typical repair costs for P1679 range from $100 to $750, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is drivable but MIL cannot illuminate to warn of throttle control system faults, creating potential awareness issues.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1679 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control / MIL Circuit
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
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