Starter Request Circuit
P0512 indicates the PCM did not receive a valid starter request signal during engine cranking. This code sets when the ignition switch signals the starter motor to engage, but the PCM fails to detect the expected signal in the starter control circuit.
What You Might Notice
- Engine cranks normally but code is stored
- Starter motor may not engage or engages intermittently
- Check engine light illuminated
- No start condition or difficulty starting
- Clicking sound when turning key but engine doesn't crank
Most Common Causes
- 1
Defective Ignition Switch
The ignition switch fails to send a proper starter request signal to the PCM when the key is turned to the start position. This is the most common cause of P0512.
- 2
Faulty Starter Relay
The starter relay fails to activate or relay signal fails to reach the PCM, breaking the communication chain between the ignition switch and starter motor circuit.
- 3
Blown Fuses or Burnt Fusible Links
A blown fuse or damaged fusible link in the starter request circuit prevents the signal from reaching the PCM or starter motor.
- 4
Open or Shorted Wiring in Starter Circuit
Damaged, corroded, or disconnected wires in the starter request circuit prevent proper signal transmission between the ignition switch, relay, and PCM.
How to Diagnose It
- 1
Check Defective Ignition Switch — The ignition switch fails to send a proper starter request signal to the PCM when the key is turned to the start position. This is the most common cause of P0512.
- 2
Check Faulty Starter Relay — The starter relay fails to activate or relay signal fails to reach the PCM, breaking the communication chain between the ignition switch and starter motor circuit.
- 3
Check Blown Fuses or Burnt Fusible Links — A blown fuse or damaged fusible link in the starter request circuit prevents the signal from reaching the PCM or starter motor.
- 4
Check Open or Shorted Wiring in Starter Circuit — Damaged, corroded, or disconnected wires in the starter request circuit prevent proper signal transmission between the ignition switch, relay, and PCM.
How to Fix It
- 1
Test and Replace Ignition Switch
Use a multimeter to test the ignition switch for proper voltage output at the starter request terminal when the key is turned to start. Replace the ignition switch if it fails to produce the expected signal.
- 2
Inspect and Replace Starter Relay
Locate the starter relay in the fuse/relay panel and test it with a multimeter or relay tester. If the relay does not click or engage when power is applied, replace it with an OEM or quality aftermarket relay.
- 3
Check Fuses and Fusible Links
Inspect the fuse panel for blown fuses related to the starter circuit and check for any burnt or damaged fusible links. Replace any blown fuses and repair or replace damaged fusible links with appropriate amperage ratings.
- 4
Test and Repair Wiring and Connectors
Visually inspect the starter request circuit wiring for damage, corrosion, or loose connections. Use a multimeter to check for continuity along the circuit. Repair or replace damaged wires and clean or reconnect corroded terminals.
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