Understanding the P0705 Code: Common Issues and Diagnoses
Common Problems That Trigger the P0705 Code
The P0705 code is indicative of issues related to the Transmission Range Sensor (also known as the PRNDL input or neutral safety switch). This component plays a crucial role in conveying the transmission’s status to the transmission control module (TCM) and the powertrain control module (PCM). Here are some common problems associated with the P0705 code:
1. Defective Transmission Range Sensor (PRNDL Input)
The Transmission Range Sensor, responsible for indicating whether the transmission is in park, reverse, neutral, drive, low, 2nd, 3rd, etc., may be faulty. The PCM may not receive accurate signals, leading to the P0705 code.
2. Defective Transmission Range Sensor Wiring or Connector
Issues with the wiring or connector of the Transmission Range Sensor can disrupt the transmission’s communication with the TCM and PCM. This may result in inconsistent data transmission, triggering the P0705 code.
3. Defective Valve Body
A malfunctioning valve body can contribute to the P0705 code. The valve body plays a role in controlling the hydraulic passages, and defects can impact the overall performance of the transmission.
4. Defective Manual Shift Valve Linkage
The manual shift valve linkage, if faulty, can affect the accurate reporting of transmission status by the Range Sensor. This malfunction may lead to the setting of the P0705 code.
5. Dirty Transmission Fluid
The presence of dirty transmission fluid can restrict hydraulic passages, causing disruptions in the transmission system. This restriction may result in inaccurate data transmission from the Range Sensor, triggering the P0705 code.
When dealing with the P0705 code, it’s crucial to avoid common misdiagnoses to ensure an accurate resolution. Some potential misdiagnoses include:
1. Engine Misfire Problem
Confusing the P0705 code with an engine misfire issue can lead to incorrect diagnostic procedures. It’s essential to focus on the transmission-related components when addressing the P0705 code.
2. Internal Transmission Problem
Misattributing the issue to an internal transmission problem without considering the Transmission Range Sensor can result in ineffective repairs. Accurate diagnosis is key to resolving the P0705 code.
3. Driveline Problem
Incorrectly identifying driveline problems as the root cause of the P0705 code can lead to unnecessary repairs. Thorough testing and analysis of the Transmission Range Sensor are essential for a precise diagnosis.
Polluting Gases Expelled
Understanding the implications of the P0705 code extends beyond the immediate transmission concerns. It also involves addressing the emission of polluting gases:
1. HCs (Hydrocarbons)
Unburned droplets of raw fuel contribute to unpleasant smells, affect breathing, and play a role in smog formation.
2. CO (Carbon Monoxide)
Partially burned fuel, while odorless, is a deadly poisonous gas. It poses risks to both the environment and human health.
3. NOX (Oxides of Nitrogen)
One of the key contributors to smog formation, NOX, becomes problematic when exposed to sunlight.
P0705 Diagnostic Theory for Shops and Technicians
When the P0705 code is triggered, it indicates a lack of clear, rational changes in data and electrical signals from the Transmission Range Sensor. This inconsistency, especially during vehicle motion, requires a systematic diagnostic approach:
1. Identifying Irrational Conditions
The P0705 code may be set when the vehicle is moving, but the Range Sensor reports the transmission is in park. This irrational condition prompts further investigation.
2. Test Drive and Data Monitoring
Conducting a test drive at speeds between 15-35 mph is crucial for duplicating code-setting conditions. Monitoring scan data helps assess the accuracy of information transmitted by the Range Sensor to the TCM and PCM.
3. Pinpoint Tests and Voltage Checks
Performing pinpoint tests, including voltage drops and continuity tests on the Transmission Range Sensor, is essential. Back probing the sensor isolates it from the wiring harness, aiding in identifying potential problems.