P0690 Code: ECM/PCM Power Relay Circuit High

Modern vehicles are equipped with multiple systems that work together to guarantee smooth performance. They rely on computers such as the PCM (powertrain control module) to monitor the operation of their engines.

Code P0690 is one of several trouble codes related to a fault with a circuit for the electronic control module (ECM) or powertrain control module (PCM). Know more about it through this article.

What Does the P0690 Code Mean?

Diagnostic trouble code P0690 stands for “ECM/PCM Power Relay Circuit High.” The code is set once the PCM detects an issue in the relay that supplies it or its control circuits with voltage.

Your vehicle’s PCM is equipped with a power relay supplies the PCM circuits with the right amount of battery voltage.

In a typical circuit, battery voltage is supplied constantly on one wire, while ground is connected as needed on another. The third circuit is usually responsible for carrying a signal from the ignition switch. There’s a fourth wire that supplies voltage to the PCM when the relay is grounded and closes.  If the PCM detects a high voltage condition on the power relay sense circuit, it will store the code P0690 and illuminate the check engine light.

Note: The definition of code P0690 can differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

What Are the Common Causes of the P0690 Code?

• Malfunctioning power relay
• Circuit issues, such as a related component that’s damaged or a poor connection
• An issue with the PCM

What Are the Common Symptoms of the P0690 Code?

• Illuminated check engine light
• Vehicle cranks but won’t start

How to Diagnose the P0690 Code

DTC P0690 can be logged in various vehicles.  However, this does not mean that there’s a universal solution for this issue. Remember that vehicles can be structured differently per manufacturer.

Take your car to an auto repair shop and have it diagnosed by a mechanic if you’re unfamiliar with the PCM, ECM, or vehicle repair in general.

How to Fix the P0690 Code

Clearing trouble codes isn’t always easy. P0690 involves circuits within the PCM, so repairs can be complicated if you don’t have the right tools and adequate experience. If you’re not familiar with vehicle repair, we recommend taking your vehicle to a mechanic.

If you’re an experienced DIYer who wants to do the job yourself, we recommend doing your research and brushing up on vehicle-specific repair information.

Repair manuals like those from Chilton or a subscription to an online repair database can give you information on the correct diagnostic and repair procedure to clear code P0690.