Experiencing issues with your 1997 Toyota RAV4’s transmission? If you’ve encountered the OBD2 code P1715, you’re likely facing a “NC2 Revolution Sensor Circuit Malfunction.” This article delves into understanding this code, its potential causes, and steps you can take to diagnose the problem, specifically for the 1997 Toyota RAV4 model.
The original poster, a 1997 Toyota RAV4 owner, is grappling with this exact issue and seeking clarity on the P1715 code. They’ve helpfully shared their troubleshooting steps, which we can use as a starting point to understand and address this problem more comprehensively.
Understanding the OBD2 Code P1715 on a 1997 Toyota RAV4
The P1715 code, as indicated by an OBD2 scanner, points to a problem with the “NC2 Revolution Sensor Circuit.” In the context of a 1997 Toyota RAV4, particularly with the Aisin A540H automatic transmission, this sensor is crucial for monitoring transmission performance.
The RAV4 owner correctly identifies two speed sensors on their transmission:
- Vehicle Speed Sensor (VSS): A three-pin connector sensor, typically easier to locate and, in theory, remove.
- NC2 Clutch Rotation Speed Sensor: A two-pin connector sensor (Part Number: 89413-32010 or 8941332010), which is the focus of the P1715 code.
It’s important to note that for a 1997 Toyota RAV4 without ABS, the P1715 code is unlikely to be related to wheel speed sensors. This distinction is crucial as some online resources and even dealerships might initially suggest wheel speed sensors as a possible cause, which is not applicable in this non-ABS scenario.
Symptoms Associated with the P1715 Code
The user describes specific symptoms experienced when the NC2 Clutch Rotation Speed Sensor is suspected to be malfunctioning:
- Transmission stuck in first gear: With the sensor disconnected, the transmission seems to remain in first gear and fails to shift to higher gears, even at higher RPMs (above 3000 RPM) and speeds around 20 mph.
- Limited speed: The inability to shift beyond first gear restricts the vehicle’s speed.
- Normal operation after reconnection: Upon reconnecting the NC2 sensor, the transmission returns to normal operation, shifting gears as expected.
These symptoms strongly suggest that the NC2 sensor plays a vital role in the transmission’s gear shifting mechanism and that its malfunction directly triggers the P1715 code.
Diagnosing the P1715 Code: Troubleshooting Steps
The RAV4 owner has already taken some valuable diagnostic steps:
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Sensor Identification and Location: Correctly identified both VSS and NC2 sensors on the transmission, located near the distributor after removing the air filter box for access.
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Resistance Testing: Measured the resistance of the NC2 sensor and found it to be within the specification range (670 ohms, high end of spec). While within spec, the user suspects it might still be faulty due to its high-end reading and the symptoms.
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Sensor Disconnection Test: Driving the vehicle with the NC2 sensor disconnected replicated the gear shifting problem and triggered the described symptoms, reinforcing the sensor’s involvement.
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ABS Check: Confirmed the absence of ABS on their 1997 RAV4, eliminating wheel speed sensors as a potential cause for the P1715 code in their case.
Further Diagnostic Considerations:
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Bench Testing the VSS: The user mentions difficulty removing the VSS. If possible, attempting to remove and bench test the VSS could rule out any issues with this sensor, although the focus is currently on the NC2 sensor.
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Transmission Fluid Temperature Sensor: The user also plans to check the Transmission Temperature sensor, noting the AT Temp light illuminates briefly at startup. While not directly related to the P1715 code, ensuring this sensor is functioning correctly is good preventative maintenance for transmission health.
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ECU Fault: The provided document excerpt (http://www.turboninjas.com/camry/ax2.pdf) suggests that an ECU fault could also trigger a similar code (P1705 in the document, similar to P1715). While less likely than a sensor issue, an ECU problem should be considered if sensor replacement doesn’t resolve the P1715 code.
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Wiring and Connections: Inspect the wiring and connectors for the NC2 sensor circuit. Look for any signs of damage, corrosion, or loose connections that could be causing intermittent signal issues.
Potential Misconceptions and Clarifications
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Center Differential Lock: The user raises an important point about the sensors potentially being related to the center differential lock rather than solely gear shifting. While the NC2 sensor clearly impacts gear shifting in this case, further investigation into its role in the center differential lock system of the 1997 RAV4 might be beneficial for a complete understanding.
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Code Definition Variations: OBD2 code definitions can sometimes vary slightly between manufacturers and models. While P1715 generally points to a revolution sensor circuit malfunction, always refer to the specific repair manual or diagnostic resources for the 1997 Toyota RAV4 and A540H transmission for the most accurate interpretation.
Conclusion: Next Steps for Troubleshooting P1715
Based on the symptoms and initial diagnostics, the NC2 Clutch Rotation Speed Sensor (Part Number: 89413-32010 or 8941332010) is a prime suspect for the P1715 code on a 1997 Toyota RAV4 with an Aisin A540H automatic transmission.
The next logical steps for the RAV4 owner, and anyone facing this issue, include:
- Replacing the NC2 Clutch Rotation Speed Sensor: Given the strong indication that this sensor is the source of the problem, replacement is a reasonable next step.
- Verifying Wiring and Connections: Before and after sensor replacement, thoroughly inspect the wiring and connectors for any damage.
- Clearing the OBD2 Code: After addressing the suspected issue, clear the P1715 code using an OBD2 scanner and test drive the vehicle to confirm the code does not return and the transmission operates normally.
- Considering ECU Diagnosis (If Necessary): If sensor replacement and wiring checks don’t resolve the issue, further diagnostic steps might involve evaluating the ECU for potential faults, although this is less common.
By systematically following these diagnostic steps, owners of a 1997 Toyota RAV4 experiencing the P1715 code can effectively troubleshoot and address the “NC2 Revolution Sensor Circuit Malfunction” and restore their vehicle’s transmission performance.
