What is a PCM control circuit?
The PCM (powertrain control module) receives data about the vehicle’s operating conditions from various areas in the system. In order to work properly, the PCM is supplied with power by a relay, which uses a battery voltage signal, a ground signal, and an ignition switch input signal.
What is the fault code for the PCM?
P0685 is the fault code for ECM/PCM Power Relay Control Circuit /Open. The PCM (powertrain control module) receives data about the vehicle’s operating conditions from various areas in the system.
What to do if your PCM Power relay is open?
However, if the ground circuit shows a voltage, the circuit is shorted to battery positive; find and repair the short circuit. Check for system voltage at the PCM connector; if this voltage is low or absent, test this circuit for open circuits, or determine the reason for the low system voltage.
What does PCM error code p0651 mean?
When Error Code P0651 is stored, this means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected an open circuit for a specific sensor; which in this case is designated as “B”. In diagnosing for this code, the term ‘open’ cold be substituted for ‘absent’.
What causes a trouble code on an ECM?
As with any trouble code, there could be a wide variety of potential causes. One of the most common is simply a bad PCM relay. Other possibilities include a blown fuse, a shorted circuit, a faulty connection, battery problems such as a cable defect, and rarely, a bad PCM or ECM.
What is the trouble code for a PCM?
The P0686 trouble code detects a voltage error with the ECM/PCM power relay control circuit. The P0868 code is a standard OBD-II trouble code that notes a voltage error with the relay control circuit that is responsible for supplying the powertrain control module (PCM) and engine control module (ECM) with power.
What is fault code for ECM / PCM Power relay?
Wiring, ECM/PCM power relay. We recommend Torque Pro. OBD II fault code P0685 is a generic code that is defined as “ECM/PCM power relay -circuit open”, and is set when the PCM (Powertrain Control Module) detects that its own power supply has failed, or if it detects a low voltage in the circuit that supplies it with power.
When Error Code P0651 is stored, this means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected an open circuit for a specific sensor; which in this case is designated as “B”. In diagnosing for this code, the term ‘open’ cold be substituted for ‘absent’.
Is there a way to fix a bad PCM?
“Fixing” a bad PCM is an extremely complicated process. Although a PCM repair always involves intricate circuit board repairs requiring lots of time and effort which need to be carried out by a trained professional with appropriate knowledge and materials, vehicle owners can benefit from learning first about how to diagnose these PCM issues.