What Does P1787 Mean?
The reversing light circuit has been detected as shorted to ground. This means excessive current is flowing through the backup light circuit, likely due to damaged wiring or a faulty component grounding out the circuit.
Common Causes
40%
Damaged or pinched backup light wiring harness
30%
Failed neutral safety switch or backup light switch
15%
Shorted backup light bulb socket or housing
10%
Water intrusion in connector causing short circuit
5%
Damaged transmission range sensor or wiring
Diagnostic Steps
1
Step 1: Visually inspect backup light wiring harness for visible damage, chafing, or pinch points
2
Step 2: Disconnect backup light bulbs and check if short code clears to isolate circuit location
3
Step 3: Check resistance to ground on backup light circuit with lights disconnected
4
Step 4: Inspect neutral safety switch connector for corrosion or water damage
5
Step 5: Test neutral safety switch operation and continuity in park and reverse positions
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
The reversing light circuit has been detected as shorted to ground. This means excessive current is flowing through the backup light circuit, likely due to damaged wiring or a faulty component grounding out the circuit.
The most common cause of P1787 (Reversing Light Circ. Short to Ground) is: Damaged or pinched backup light wiring harness
Typical repair costs for P1787 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Backup lights may not function properly, reducing visibility when reversing and making vehicle less visible to others. Repair recommended for safe operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1787 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Transmission Controls / Lighting
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
