OBD Guide

B2603

DRL Relay Control Circuit Shorted To Battery Positive Voltage

B2603 is an OBD-II diagnostic trouble code meaning: DRL Relay Control Circuit Shorted To Battery Positive Voltage. Common causes: short circuit in wiring harness, faulty drl relay. Estimated repair cost: $33–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–89 (est.)

Symptoms

  • Daytime running lights do not turn on
  • DRLs are constantly on (do not turn off)
  • Dashboard warning light
  • The error is stored in the ECU memory after reset

Causes

  • Short circuit in wiring harness
  • Faulty DRL relay
  • Damage to wire insulation
  • Problems in the relay power circuit
  • Control unit malfunction

How to Fix

  1. Check the integrity of the wiring harness to the DRL relay
  2. Check the condition of the DRL relay (winding resistance)
  3. Check the voltage in the relay control circuit
  4. Inspect connections and connectors for oxidation
  5. If necessary, replace relays or damaged wires
  6. Clear error codes and check system operation

Related codes

FAQ

What does the B2603 code mean?

B2603 is an OBD-II diagnostic trouble code that indicates: DRL Relay Control Circuit Shorted To Battery Positive Voltage

What causes a B2603 error code?

The most common causes of B2603 include: Short circuit in wiring harness; Faulty DRL relay; Damage to wire insulation; Problems in the relay power circuit.

How do I fix a B2603 diagnostic trouble code?

To fix B2603: Check the integrity of the wiring harness to the DRL relay. Check the condition of the DRL relay (winding resistance). Check the voltage in the relay control circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B2603?

Limited driving only, diagnose soon

How much does it cost to fix B2603?

The estimated repair cost for B2603 is $33–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat