What Does B1973 Mean?
This code indicates the Body Control Module (BCM) has detected that the passenger rear seat down switch circuit is shorted directly to battery voltage when it should be operating at a lower reference voltage or ground signal. The BCM monitors this switch to determine seat position status for safety systems, comfort features, or cargo area management. The short to battery voltage means the circuit is receiving constant 12+ volts instead of the expected signal range.
Common Causes
40%
Damaged or chafed wiring harness causing direct contact with battery voltage source, often at seat hinge points or routing areas with movement
30%
Failed passenger rear seat down position switch with internal short circuit
20%
Corroded or moisture-damaged connector terminals causing cross-circuit short to adjacent battery-powered circuit
10%
Body Control Module internal circuit fault causing incorrect voltage detection or shorted input driver
Diagnostic Steps
1
Step 1: Perform visual inspection of the passenger rear seat down switch and associated wiring harness, paying special attention to areas where the harness passes through seat hinge points, under carpeting, and near metal brackets. Look for chafed insulation, pinched wires, or visible damage
2
Step 2: Disconnect the passenger rear seat down switch connector and measure voltage at the BCM side of the circuit using a digital multimeter. With ignition on, you should see 0 volts or a low reference voltage (typically 0-5V depending on manufacturer). If you see battery voltage (12+ volts), the short exists in the wiring harness between the switch and BCM
3
Step 3: If battery voltage is NOT present at the disconnected switch connector, measure the resistance of the switch itself across its terminals in both seat positions. Compare readings to manufacturer specifications (typically open circuit in one position, closed/low resistance in another). A reading showing continuity to a power circuit indicates internal switch failure
4
Step 4: Inspect all connectors in the circuit for corrosion, pushed-back pins, or moisture intrusion. Clean connectors with electrical contact cleaner and check for proper pin tension. Pay attention to any adjacent circuits in the same connector that carry battery voltage
5
Step 5: If wiring harness damage is found, repair the damaged section using proper splicing techniques with heat shrink tubing and dielectric grease. If switch is faulty, replace the switch assembly. Clear codes and cycle the seat through all positions while monitoring live data to verify proper voltage range (should transition between ground and reference voltage, not battery voltage)
6
Step 6: After repair, perform a final verification test by cycling the seat fold mechanism multiple times while monitoring the switch circuit status on live data to ensure no intermittent faults and confirm the code does not return
Estimated Repair Cost
$150 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected that the passenger rear seat down switch circuit is shorted directly to battery voltage when it should be operating at a lower reference voltage or ground signal. The BCM monitors this switch to determine seat position status for safety ...
The most common cause of B1973 (Passenger Rear Seat Down Switch Circuit Short to Battery) is: Damaged or chafed wiring harness causing direct contact with battery voltage source, often at seat hinge points or routing areas with movement
Typical repair costs for B1973 range from $150 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This fault does not affect vehicle drivability or safety-critical systems and it is safe to continue driving. The primary impact is that the BCM may not correctly detect seat position, which could affect related comfort features, cargo area warnings, or seat belt reminder systems for that seating position.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1973 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Seating System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
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