Encountering an OBD2 code related to your Chevrolet Equinox can be frustrating, especially when it impacts performance. One such issue can manifest as an “Equinox Cam Timing Off Obd2 Code,” often intertwined with fuel pressure problems. This article delves into a real-world diagnostic scenario, exploring the symptoms, troubleshooting steps, and potential causes when your Equinox exhibits signs of cam timing irregularities and related OBD2 codes.
The case we’ll examine involves a Chevrolet Equinox experiencing high fuel pressure during deceleration, triggering a specific OBD2 code. Interestingly, there were no direct cam timing codes present initially. Let’s break down the diagnostic journey to understand how cam timing issues can surface even without explicit cam-related codes.
Symptoms and Initial OBD2 Code
The primary symptom reported was elevated fuel pressure during deceleration. While driving, the fuel rail pressure would remain abnormally high when the driver released the accelerator pedal. This condition would trigger an OBD2 code, specifically related to fuel pressure performance. However, during acceleration, the fuel pressure behaved as expected, matching the desired pressure. A new Original Equipment (OE) fuel pump was installed, but this replacement unfortunately did not resolve the issue.
Further investigation with a diagnostic scanner revealed a significant anomaly: the scanner was not displaying any cam position data. All cam position values were registering as zero, indicating a potential problem within the cam timing system, despite the absence of dedicated cam timing malfunction codes. Furthermore, the scanner indicated “MALFUNCTION” for low voltage, high voltage, and open circuit tests for both cam timing solenoids. Again, no specific OBD2 codes were directly linked to these solenoid malfunctions.
Diagnostic Steps and Findings
To pinpoint the root cause, a systematic diagnostic approach was employed:
- Circuit Testing: All four circuits connecting the Powertrain Control Module (PCM) to the cam timing solenoids were meticulously tested. Continuity and load testing were performed, confirming the integrity of the wiring.
- Solenoid Testing: The cam timing solenoids themselves were individually tested using a MultiProbe Ultra tool and were found to be functioning correctly. Activating each solenoid with the engine running resulted in noticeable engine performance changes, further validating their operational status. Notably, activating the intake solenoid caused a drop in fuel rail pressure, indicating a link between cam timing and fuel pressure regulation.
- PCM Voltage Analysis: With the solenoids disconnected, voltage readings were taken at the power side circuits from the PCM, revealing 2.47v on each. This was interpreted as a possible test voltage supplied by the PCM. However, with the solenoids connected and backprobing with a scope, no voltage was detected at all during engine operation. Attempting to control the solenoids using the scanner with the engine running was unsuccessful. Activating the solenoids with the key in the “on” position but engine off also yielded no voltage and resulted in an error message from the PCM.
- Ground Circuit Resistance: Testing the ground side of the solenoid circuits with the power off showed 0 ohms resistance to ground. With the key on, this resistance increased to 30 ohms on both ground circuits. The PCM controls the ground for these solenoids.
Alt text: Fuel rail with pressure sensor, a component relevant to fuel pressure issues in vehicles, potentially related to Equinox cam timing problems.
Suspected Cause: Faulty PCM and Secondary OBD2 Codes
Based on these findings, particularly the lack of cam position data, the inability to control the solenoids through the scanner, and the voltage anomalies, a strong suspicion emerged: a faulty PCM. The hypothesis was that the malfunctioning PCM was failing to properly control the cam timing system, which in turn was indirectly affecting the high-pressure fuel system and causing the observed fuel pressure issues and the P0089 code (Fuel Pressure Regulator Performance).
Interestingly, the initial scan using a generic OBD2 code reader at the service reception revealed additional codes: P0411, P2430, and P2440, related to the secondary air system. However, the vehicle in question was not equipped with a secondary air system, although a connector and breather hose for such a system were present. The origin of these secondary air system codes remained unclear. It was questioned whether these were spurious codes due to a scanner glitch or if a PCM replacement and reprogramming would address them.
Alt text: OBD2 scanner displaying diagnostic information, highlighting the tool used to read and interpret OBD2 codes related to car issues like Equinox cam timing problems.
Conclusion
The diagnostic process strongly suggested that a failing PCM was the most likely culprit for the “equinox cam timing off OBD2 code” symptoms and related fuel pressure issues. While no direct cam timing codes were initially present, the absence of cam position data and the solenoid control problems pointed towards a deeper issue within the PCM’s control of the variable valve timing system. The secondary air system codes were considered potentially unrelated or a scanner anomaly. Further steps would likely involve PCM replacement and reprogramming to resolve the primary cam timing and fuel pressure problems, and to ascertain if the secondary air system codes persisted afterward.
It’s important to note that while a bulletin regarding incorrect camshafts causing P0089 exists for this vehicle, the customer stated that no engine work had been performed, making a mechanical camshaft mismatch less probable in this specific case. However, this bulletin could be a point to verify if PCM replacement doesn’t fully resolve the issue.
For anyone experiencing similar symptoms with their Chevrolet Equinox, a thorough diagnostic process like the one described is crucial to accurately identify the root cause, which may indeed be related to PCM malfunction impacting cam timing and subsequently fuel pressure regulation. Consulting with a qualified mechanic is highly recommended for accurate diagnosis and repair of such complex automotive issues.
