When it comes to diagnosing code P0651, it can be tricky to determine the cause. It is a 5-Volt Reference 2 Circuit code for Cadillac vehicles, which relates to the ignition voltage being greater than 6.0 V. If the Reduced Engine Power is inactive and the ECM detects the 5-volt reference is out of range for less than 1 s, then DTCs P0641 and P0651 will run continuously. This can be quite difficult to diagnose, not just for mechanics but also for owners of Cadillac vehicles. To make it easier to identify the cause and solutions related to code P0651 for Cadillac vehicles, we have created a table below to guide you through the process.
Causes and Solutions for Cadillac Code P0651
| Causes | Solutions |
|---|---|
| ECM detects the 5-volt reference is out of range for less than 1 s | Check the wiring and connector for any signs of damage |
| Ignition is in Run or Crank | Replace the ECM if necessary |
| Ignition voltage is greater than 6.0 V | Replace the voltage regulator if necessary |
| Reduced Engine Power is Inactive | Check the service bulletins for any updates |
ECM Detects 5-Volt Reference Out of Range
When the ECM detects that the 5-volt reference is out of range for less than 1 s, it will set code P0651 for Cadillac vehicles. The first solution to this problem is to check the wiring and connector for any signs of damage. If there are any signs of damage, then it will need to be replaced.
High Ignition Voltage
Another possible cause of code P0651 is when the ignition voltage is greater than 6.0 V. In this case, the solution is to replace the voltage regulator if necessary. The voltage regulator is responsible for controlling the voltage and ensuring that it is within the proper range.
Inactive Reduced Engine Power
If the Reduced Engine Power is inactive, then the ECM will continuously set codes P0641 and P0651. The solution to this problem is to check the service bulletins for any updates. If there are any updates, then it is important to follow the instructions in the bulletin to ensure that the problem is resolved.
Conclusion
Cadillac Code P0651 can be difficult to diagnose due to its complexity. There are several possible causes, such as the ECM detecting the 5-volt reference is out of range for less than 1 s, the ignition voltage being greater than 6.0 V, or the Reduced Engine Power being inactive. By following the solutions listed in the table above, you should be able to easily identify the cause and solution for Cadillac Code P0651.
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