What Does B2174 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected a short to battery voltage on the driver's rear window remote up switch circuit. The BCM monitors the switch input signal and expects a ground or open circuit when the switch is not activated, but instead is detecting constant battery voltage on this circuit. This fault prevents proper operation of the rear driver's side window up function from the remote switch location.
Common Causes
45%
Damaged or chafed wiring harness causing direct contact with battery voltage between the switch and BCM
30%
Faulty rear driver's side window switch with internal short circuit to power supply
15%
Water intrusion or corrosion in switch connector causing cross-circuit short to battery voltage
10%
Failed Body Control Module with internal short on switch input circuit
Diagnostic Steps
1
Step 1: Disconnect the rear driver's side window switch connector and clear the code. If the code returns immediately with switch disconnected, the short is in the wiring harness between the switch and BCM. If code does not return, proceed to next step.
2
Step 2: With switch disconnected, use a digital multimeter to measure voltage on the switch connector terminal corresponding to the up signal wire (typically the BCM input side). You should read 0 volts or near-ground; if battery voltage is present, trace and repair wiring harness short to power.
3
Step 3: If no voltage is detected at the disconnected harness connector, inspect the window switch assembly for physical damage, water intrusion, or corrosion. Measure resistance across the up switch terminals; with switch not pressed, resistance should be infinite (open circuit). If continuity or low resistance is present to the power supply terminal, replace the switch.
4
Step 4: Reconnect the switch and perform a wiggle test on all door harness sections, particularly at hinge flex points and door jamb areas, while monitoring for code recurrence. Focus on areas where harness may contact metal door frame or pinch points.
5
Step 5: If all wiring and switch test normal, inspect BCM connector terminals for corrosion, bent pins, or moisture. Measure voltage at BCM connector switch input pin with switch disconnected; battery voltage here indicates BCM internal fault requiring module replacement.
Estimated Repair Cost
$100 - $650
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected a short to battery voltage on the driver's rear window remote up switch circuit. The BCM monitors the switch input signal and expects a ground or open circuit when the switch is not activated, but instead is detec...
The most common cause of B2174 (Window Driver Rear Remote Up Switch Short to Battery) is: Damaged or chafed wiring harness causing direct contact with battery voltage between the switch and BCM
Typical repair costs for B2174 range from $100 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this affects only window convenience operation. Repair at earliest convenience to restore full window functionality and prevent potential battery drain or BCM damage from prolonged short circuit condition.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2174 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Power Window System
Difficulty
Type
Generic (SAE)
Recommended Tools
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