What Does B1439 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the wiper mode select switch signal circuit. The BCM continuously monitors the electrical continuity of the wiper control switch circuit, and when it detects no signal or infinite resistance where a closed circuit should exist, it sets this fault code. This affects the windshield wiper system's ability to communicate mode selections (intermittent, low, high) to the control module.
Common Causes
45%
Faulty wiper mode select switch with internal open circuit or worn contacts
30%
Broken or corroded wiring between wiper switch and BCM, including damaged connector pins
15%
Poor ground connection or open ground circuit in wiper switch circuit
10%
Failed Body Control Module with damaged input circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of the wiper switch assembly and all accessible wiring harnesses for obvious damage, corrosion, or loose connections. Check all connector terminals for bent pins, corrosion, or moisture intrusion.
2
Step 2: Using a digital multimeter, backprobe the wiper mode select switch connector while actuating the switch through all positions. Verify continuity changes and resistance values match manufacturer specifications (typically 0-5 ohms closed, infinite ohms open).
3
Step 3: With ignition on and switch connector still attached, check for reference voltage at the switch (typically 5V or 12V depending on design). If no voltage present, trace circuit back toward BCM checking for opens or shorts to ground.
4
Step 4: Locate and test all ground connections in the wiper switch circuit using multimeter. Verify less than 0.5 ohms resistance to known good chassis ground. Clean and tighten any questionable grounds.
5
Step 5: If all wiring and grounds test good, isolate the switch by disconnecting it and testing resistance through all switch positions with multimeter directly at switch terminals. Compare readings to specifications.
6
Step 6: After repair, clear codes, cycle wiper switch through all modes multiple times, and verify proper operation. Road test with wipers activated to confirm code does not return and all wiper functions operate normally.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the wiper mode select switch signal circuit. The BCM continuously monitors the electrical continuity of the wiper control switch circuit, and when it detects no signal or infinite resistance where a closed circuit shou...
The most common cause of B1439 (Wiper Mode Select Switch Circuit Open) is: Faulty wiper mode select switch with internal open circuit or worn contacts
Typical repair costs for B1439 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive, but wiper functionality may be impaired or completely inoperative. This creates a significant safety hazard during rain or snow conditions when visibility is critical. Repair should be completed before driving in inclement weather.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1439 to identify the root cause.
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Quick Info
Category
Body
System
Windshield Wiper System
Difficulty
Type
Manufacturer
Recommended Tools
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