OBD Guide

P1503

Load Signal From Alternator DF Terminal Implausible Signal

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine Light Is On
  • Unstable engine operation at idle
  • Battery charging problems
  • Reduced power of electrical equipment
  • Periodic malfunctions in the operation of car electronics

Causes

  • Generator malfunction
  • Open or short circuit in terminal DF circuit
  • Poor contact in connectors or corrosion
  • Engine control unit (ECU) malfunction
  • Relay or fuse problems

How to Fix

  1. Check the condition of the generator and its terminals
  2. Inspect the DF terminal circuit for damage.
  3. Check contacts and connectors for corrosion
  4. Test the generator on the stand
  5. If necessary, replace the generator or repair the wiring

Related codes

Error P1503 by Vehicle Brand