What Does P1857 Mean?
The transmission control module has detected transfer case contact plate 'C' circuit is shorted to ground. This creates an abnormal current path preventing proper transfer case operation and control.
Common Causes
45%
Damaged wiring harness with exposed wire contacting chassis ground
25%
Failed transfer case contact plate 'C' with internal ground short
15%
Corroded connector allowing moisture to create ground path
10%
Transfer case actuator motor internal short to case ground
5%
TCM internal driver circuit failure
Diagnostic Steps
1
Step 1: Disconnect transfer case contact plate 'C' connector and measure resistance to ground (should be high resistance)
2
Step 2: Inspect wiring harness for pinch points, wear spots, or areas contacting metal
3
Step 3: Check contact plate 'C' mounting and grounding points for proper insulation
4
Step 4: Test resistance of contact plate 'C' circuit at component with connector disconnected
5
Step 5: Perform wiggle test on harness while monitoring circuit resistance to identify intermittent shorts
Estimated Repair Cost
$150 - $850
Parts + labor, varies by vehicle and location
The transmission control module has detected transfer case contact plate 'C' circuit is shorted to ground. This creates an abnormal current path preventing proper transfer case operation and control.
The most common cause of P1857 (Transmission Transfer Case Contact Plate 'C' Short Circuit To Ground) is: Damaged wiring harness with exposed wire contacting chassis ground
Typical repair costs for P1857 range from $150 to $850, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Transfer case function may be disabled or erratic, potentially causing unexpected drivetrain engagement. Avoid using 4WD until issue is resolved.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1857 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transfer Case / 4WD System
Difficulty
Type
Manufacturer
Recommended Tools
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