What Does P1677 Mean?
The PCM has detected the drive-by-wire MIL circuit is shorted to a positive voltage source. This means excessive voltage is present on the warning lamp circuit, likely causing the MIL to illuminate continuously or erratically.
Common Causes
40%
Short to battery voltage in wiring harness between PCM and instrument cluster
25%
Faulty instrument cluster with internal short in MIL circuit
20%
Damaged or pinched wiring causing intermittent short to power
10%
PCM internal MIL output driver transistor shorted to voltage
5%
Aftermarket accessory or trailer wiring causing cross-circuit short
Diagnostic Steps
1
Step 1: Disconnect instrument cluster connector and measure voltage on MIL circuit wire, should be zero with key on
2
Step 2: Inspect wiring harness for damage, pinch points, or contact with hot circuits throughout length
3
Step 3: With cluster disconnected, check for voltage at PCM MIL output terminal, should command to ground when on
4
Step 4: Check for recent installation of aftermarket accessories that may share wiring routes with MIL circuit
5
Step 5: Perform insulation resistance test on MIL circuit wire to detect high-resistance shorts
Estimated Repair Cost
$100 - $700
Parts + labor, varies by vehicle and location
The PCM has detected the drive-by-wire MIL circuit is shorted to a positive voltage source. This means excessive voltage is present on the warning lamp circuit, likely causing the MIL to illuminate continuously or erratically.
The most common cause of P1677 (Drive By Wire MIL Circuit Short To Positive) is: Short to battery voltage in wiring harness between PCM and instrument cluster
Typical repair costs for P1677 range from $100 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
MIL may illuminate constantly regardless of actual system status, causing driver confusion. May mask actual electronic throttle control problems. Vehicle remains safe to operate.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1677 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control Warning System
Difficulty
Type
Manufacturer
Recommended Tools
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