P0512 Starter Request Circuit Trouble Code

P0512 Starter Request Circuit

OBD-II Trouble Code Technical Description

Starter Request Circuit

What does that mean?

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to all 1996-newer vehicles (Dodge, Chrysler, Hyundai, Jeep, Mazda, etc.). Although generic, the specific repair steps may vary depending on make/model.

Any time that I encounter a stored code P0512, it means that the powertrain control module (PCM) has detected a malfunction in the starter request circuit. In this case, the word starter refers to the engine starter.

 

Although the starter is supplied with constant battery voltage from the positive cable, the starter request signal originates from the ignition switch. When the ignition key is placed into the ignition cylinder and turned to the start position, it actuates the electrical portion of the ignition switch and closes a set of heavy-duty contacts, completing the starter request circuit. When the starter request circuit is completed, a battery voltage signal is sent to the starter solenoid (or the starter relay on some models). In the vehicle which you are attempting to diagnose, it means that a starter request signal should also be sent to the PCM. Since a code P0512 has been stored, the PCM has probably not received the starter request signal.

Once the starter request signal is received by the starter solenoid, the starter motor begins to spin and a small cog is pushed in the direction of the engine where the teeth of the cog intermesh with the teeth of the flywheel ring gear. This turns the engine crankshaft and helps to initiate startup.

Consult a reliable vehicle information source (All Data DIY is great) to see if the vehicle in question is equipped with a starter relay. If so, you’ll need to locate the relay and the system wiring diagram. Typically, the ignition switch supplies the starter relay with a starter request signal. After the relay receives the signal, the relay then provides the starter and the PCM with a starter request signal. After that, the starter and solenoid function in exactly the same manner as the vehicle that has no starter relay.

Even if there are no symptoms exhibited, if the PCM fails to receive the starter request signal and the engine is started, a code P0512 will be stored and a malfunction indicator lamp may be illuminated. Some vehicles require multiple ignition cycles (with a failure) for the MIL to be illuminated.

Severity & Symptoms

If the engine cranks normally, a P0512 can be addressed at your convenience. Obviously, if the engine will not start, the code will need to be addressed with a certain degree of urgency.

Symptoms of a P0512 code may include:

The engine may fail to start Delayed starter engagement (startup may require multiple key cycles) PCM power circuit failure or ignition system circuit failure codes may accompany this code There are often no symptoms at all

Causes

Possible causes for this code include:

Defective ignition switch Blown fuses or burnt fusible links Faulty starter relay Open or shorted circuits in the starter request circuit PCM fault or PCM programing error

Diagnostic and Repair Procedures

A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known issue with a known fix put out by the manufacturer and can save you time and money during diagnosis.

When diagnosing a P0512, a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a vehicle information source (such as All Data DIY) will be necessary.

Begin with a visual inspection of all related wiring and connectors. This is also a good time to check all fuses, using the DVOM. Check starter system fuses while the starter is being engaged because fuses on unloaded circuits may appear operational un

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