What Does B1438 Mean?
This code indicates the Body Control Module (BCM) has detected an electrical fault in the wiper mode select switch circuit. The BCM monitors the switch that allows the driver to select different wiper speeds and modes (intermittent, low, high). The fault could be an open circuit, short circuit, high resistance, or loss of communication between the switch and the BCM.
Common Causes
40%
Faulty wiper mode select switch with internal contact wear or failure
30%
Damaged or corroded wiring harness between wiper switch and BCM
20%
Corroded or loose electrical connector at wiper switch or BCM
10%
Failed Body Control Module or internal BCM circuit fault
Diagnostic Steps
1
Step 1: Perform visual inspection of wiper switch and all associated connectors for corrosion, damage, or loose pins. Check steering column harness for visible damage or pinching.
2
Step 2: Using a digital multimeter, test the wiper mode select switch for proper resistance values across all switch positions according to manufacturer specifications. Document readings in each mode position.
3
Step 3: With ignition on, backprobe the wiper switch connector and verify proper voltage supply (typically 5V or 12V reference) and ground circuits using multimeter. Check for voltage drops exceeding 0.1V on ground circuit.
4
Step 4: Test continuity of all wiper switch signal wires from the switch connector to the BCM connector with ignition off. Look for opens, shorts to ground, or shorts to power (resistance should typically be under 5 ohms).
5
Step 5: If all circuits test normal, substitute a known-good wiper switch assembly to confirm switch failure. Monitor live data with scan tool while operating replacement switch through all positions.
6
Step 6: Clear codes and perform functional test of wiper system through all modes. Verify code does not return and BCM properly receives all switch position signals.
Estimated Repair Cost
$150 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an electrical fault in the wiper mode select switch circuit. The BCM monitors the switch that allows the driver to select different wiper speeds and modes (intermittent, low, high). The fault could be an open circuit, short circuit, high...
The most common cause of B1438 (Wiper Mode Select Switch Circuit Failure) is: Faulty wiper mode select switch with internal contact wear or failure
Typical repair costs for B1438 range from $150 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving with reduced wiper functionality. Repair is recommended before adverse weather conditions as wipers may not operate properly or may be stuck in one mode, reducing visibility during rain or snow.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1438 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body Controls - Wiper/Washer System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
