B1973

Code

Other B — Body

Passenger Rear Seat Down Switch Circuit Short to Battery

Brand: Other

Type: B — Body

Views: UK: 26 EN: 41 RU: 32

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed wiring contacting battery positive or another live circuit
Corroded or pushed‑in connector terminal creating a direct feed from battery
Shorted switch (internal failure) or stuck contacts
Water intrusion into connector or harness causing a conductive path to battery
Aftermarket accessory wiring tied into seat circuit
Faulty body/control module input (rare)

Symptoms

DTC B1973 stored in body/control module
Passenger rear seat down function intermittent or inoperative
Seat position not recognized or incorrect seat status message
Possible parasitic draw or battery drain in severe shorts
Related seat or convenience features disabled

What to check

Read and record DTC and freeze frame with a scan tool, then clear and attempt to reproduce
Visual inspection of seat wiring, connectors, and terminals for damage, corrosion, or water
Backprobe the switch connector and the corresponding harness/BCM connector with key ON (engine OFF) to measure voltage
Disconnect the seat down switch and check if DTC returns (helps isolate switch vs. harness/module)
Wiggle testing of wiring while observing live data for intermittent changes
Inspect for aftermarket devices tied into seat or power circuits

Signal parameters

Normal: circuit pulled low or to reference (near 0 V) when switch is open; near battery voltage (≈12–14.5 V) when switch closed (exact logic depends on vehicle)
Fault condition: circuit reads near battery voltage with switch in the open position (indicates short to battery)
Expected current draw: very low (milliamps) for switch input; a short will show higher than expected current
Resistance checks: a short to battery shows low resistance between circuit and battery positive; good circuits show high resistance to battery positive when switch is open

Diagnostic algorithm

Retrieve codes and freeze frame. Attempt to reproduce condition and note when the code sets.
Perform a careful visual inspection of seat wiring, especially at the hinge, under-seat routing, and connectors for pin damage, chafe, or corrosion.
With ignition ON (engine OFF) and using proper backprobing technique, measure voltage at the seat down switch connector with the switch connected and in both positions. Record readings.
Disconnect the seat down switch harness connector. With ignition ON, measure voltage on the harness side input pin. If it still shows battery voltage with the switch disconnected, the short is in the harness or upstream (not the switch).
If the harness side is not at battery voltage when the switch is disconnected, measure directly at the switch pins to determine if the switch is shorted internally.
If short persists on harness side, isolate sections of the harness by disconnecting intermediate connectors (seat module, junctions, BCM) and rechecking until you find the segment showing battery voltage with switch removed.
Check continuity and resistance between the suspect circuit and battery positive and to ground. Low resistance to positive indicates a short to battery; low resistance to ground indicates short to ground (different fault).
Inspect and repair damaged wiring (splice repair or harness replacement), repair corroded terminals, or replace the switch as required. If wiring repairs are performed, protect routing at hinge points with loom and retainers.
After repair, clear codes, retest operation through several cycles and verify no code returns. Confirm proper voltages and function with scan tool.

Likely causes

Wiring damage at seat hinge or under seat (most common)
Connector corrosion/poor mating at the switch or harness plug
Failed seat down switch
Accessory or repair wiring incorrectly connected to a constant 12 V feed

Fault status

⚠️ Status

B1973 — Passenger Rear Seat Down Switch Circuit Short to Battery. The switch input is seeing constant battery voltage when it should change state. Inspect switch, connectors and harness for short to battery.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours