Dealing with a check engine light in your 2000 Saturn can be frustrating, especially when you encounter a code like P0708. This diagnostic trouble code (DTC) is related to your vehicle’s transmission range sensor, and it’s crucial to address it promptly to avoid potential transmission damage. As an expert in auto repair at cardiagnosticnearme.com, I’m here to guide you through understanding, diagnosing, and potentially resolving the P0708 code specifically for your 2000 Saturn.
Decoding OBD2 Code P0708 on Your 2000 Saturn
The P0708 code is a generic powertrain code that applies to OBD-II equipped vehicles, including your 2000 Saturn. Specifically, P0708 indicates a “Transmission Range Sensor ‘A’ Circuit High” issue. The transmission range sensor (TRS), sometimes referred to as the inhibitor switch or neutral safety switch, plays a vital role in informing your Saturn’s Powertrain Control Module (PCM) or Transmission Control Module (TCM) about the position of the gear shift lever.
Think of the TRS as the communication bridge between your gear selector and the car’s computer. It sends signals to the PCM/TCM, indicating whether you’ve selected Park, Reverse, Neutral, Drive, or Low gears. “Circuit High” in the code description means the PCM/TCM is detecting an abnormally high voltage signal from the “A” circuit of the TRS. This can happen when the sensor or its wiring is malfunctioning, leading to confusion in the transmission control system.
When the PCM/TCM receives conflicting signals or an implausible signal – like indicating two gear positions simultaneously for an extended period (over 30 seconds) – it triggers the P0708 code. If this malfunction occurs in two consecutive driving cycles (key on-off, off-on), the check engine light will illuminate. Furthermore, your 2000 Saturn might enter a “fail-safe” or “limp-home” mode to protect the transmission, which can severely limit driving performance.
Example of an external Transmission Range Sensor (TRS):
Symptoms of a P0708 Code in a 2000 Saturn
Recognizing the symptoms associated with a P0708 code is the first step in addressing the issue in your 2000 Saturn. The most noticeable symptoms include:
- Check Engine Light Illumination: This is the most direct indicator. The malfunction indicator lamp on your dashboard will light up to alert you to a problem.
- Reduced Engine Power: You may experience a significant lack of power, especially when starting from a stop. This is often because the transmission starts in a higher gear, like third gear, in limp-home mode.
- Transmission Problems: Your 2000 Saturn’s transmission might exhibit erratic shifting, be stuck in a single gear, or refuse to shift gears properly. This is due to the PCM/TCM’s inability to accurately determine the gear position.
Ignoring these symptoms and continuing to drive your 2000 Saturn with a P0708 code can lead to more serious and costly transmission damage. It’s crucial to investigate and repair the issue as soon as possible.
Potential Causes of P0708 in Your 2000 Saturn
Several factors can trigger the P0708 code in your 2000 Saturn. Identifying the root cause is essential for effective repair. Common causes include:
- Faulty Transmission Range Sensor (TRS): The sensor itself might be defective due to wear, internal electrical failure, or damage. This is a frequent culprit for P0708 codes.
- Misadjusted Transmission Shift Cable/Linkage: If the cable or linkage connecting your gear shift lever to the TRS is misadjusted, it can cause the sensor to send incorrect signals to the PCM/TCM.
- Damaged Wiring or Connectors: Wiring harnesses or connectors associated with the TRS circuit can become damaged, corroded, or shorted, leading to high resistance or open circuits and triggering the P0708 code.
- Misadjusted Range Sensor: Even a functioning TRS can cause issues if it’s not correctly aligned or positioned on the transmission.
- PCM or TCM Failure (Rare): While less common, a fault within the PCM or TCM itself can, in rare cases, cause a P0708 code. However, it’s more likely that a PCM/TCM issue is a consequence of a short circuit in the TRS circuit rather than the primary cause.
Diagnosing and Repairing P0708 on a 2000 Saturn
Diagnosing the P0708 code on your 2000 Saturn requires a systematic approach. Here are steps you or a qualified technician can take:
- Initial Inspection: Begin by visually inspecting the transmission shift cable and linkage for any signs of damage, looseness, or misadjustment. Ensure they move freely and are properly connected.
- Scan Tool Diagnosis: Using an OBD-II scan tool is the most efficient way to diagnose P0708. The scan tool will confirm the presence of the code and may provide additional data or freeze frame information to aid in diagnosis.
- TRS Circuit Testing: If a scan tool is unavailable, you can use a digital voltmeter to test the TRS circuit. With the ignition key in the “ON” position (engine off – KOEO), backprobe the sensor connector while it’s still connected. Have an assistant shift through each gear position one by one. Each signal circuit should show voltage in only one gear position. Voltage in multiple positions suggests a faulty TRS.
- Wiring Inspection: Carefully inspect the wiring and connectors associated with the TRS circuit for any signs of damage, corrosion, or shorts. Repair or replace any damaged wiring as needed.
- TRS Replacement: Based on diagnostic findings, replacing the transmission range sensor is often necessary. Ensure you use a compatible replacement part for your 2000 Saturn.
- Shift Linkage Adjustment: After replacing the TRS, or if misadjustment is suspected, properly adjust the transmission shift cable/linkage according to your 2000 Saturn’s service manual specifications.
- Code Clearing and Verification: After completing repairs, clear the P0708 code using a scan tool and perform a test drive to ensure the code does not return and that your 2000 Saturn shifts correctly.
Important Note: While diagnosing and repairing a P0708 code might be possible for a DIY enthusiast, dealing with transmission issues can be complex. If you are not comfortable with automotive electrical testing or transmission repairs, it’s always best to seek assistance from a qualified automotive technician to ensure accurate diagnosis and repair of your 2000 Saturn.
If you’re still encountering issues with the P0708 code on your 2000 Saturn after attempting these steps, consider seeking further advice in our FREE car repair forums. Our community of experts and enthusiasts may offer valuable insights to help you resolve your specific situation.
Disclaimer: This information is for informational purposes only and should not be considered professional repair advice. We are not liable for any actions taken based on this information. Always consult a qualified technician for diagnosis and repair.
