Here's a breakdown of how to troubleshoot and potentially fix the problem:
1. Obtain More Information:
* Check for other codes: A P0700 is almost always accompanied by other diagnostic trouble codes (DTCs). Use an OBD-II scanner (available at most auto parts stores) to read all the codes, not just the P0700. These additional codes will pinpoint the specific problem within the transmission control system. Write them all down.
* Check the transmission fluid: Inspect the fluid level and condition. Is it low? Is it burnt (smells burnt, dark brown or black)? Low or contaminated fluid can cause numerous transmission problems. If it's low, add the correct type and amount (consult your owner's manual). If it's burnt, a transmission fluid change (or flush) might help, but it may indicate more serious internal damage.
2. Common Causes of P0700 & Associated Codes (Examples):
The following are *possible* causes, depending on the accompanying codes. You need those other codes to narrow it down:
* Transmission Range Sensor (TRS) Issues: This sensor tells the PCM (Powertrain Control Module) what gear the transmission is in. A faulty TRS can generate a P0700 and other codes related to gear selection.
* Transmission Speed Sensor (TSS) Problems: This sensor tells the PCM the speed of the transmission output shaft. Problems here can lead to shifting problems and codes like P0700.
* Shift Solenoid Problems: These solenoids control the shifting of the transmission. A malfunctioning solenoid can cause erratic shifting, slipping, and the P0700.
* Wiring Issues: Problems with the wiring harness connecting the transmission to the PCM (broken wires, corrosion, short circuits) are a common cause.
* Throttle Position Sensor (TPS) problems: While not directly related to the transmission, a faulty TPS can sometimes affect the transmission control system and trigger a P0700.
* PCM Issues: In rare cases, the PCM itself could be faulty, though this is less common.
3. Diagnosis & Repair:
* Professional Diagnosis: The best course of action is to take your Neon to a qualified mechanic or transmission specialist. They have the tools and expertise to properly diagnose the underlying problem indicated by the accompanying codes. This is especially important since transmission repairs can be costly.
* DIY Approach (Advanced): If you're mechanically inclined and have experience working on cars, you *might* be able to diagnose and repair the problem yourself, but it's significantly more complex and risky. You'll need an OBD-II scanner, a wiring diagram for your specific vehicle, and the ability to test components with a multimeter.
Important Notes:
* Safety First: Working on a transmission can be dangerous. Be cautious and follow all safety precautions.
* Cost: Transmission repairs can be expensive, especially if internal components need replacement. Get multiple quotes before undertaking repairs.
* Year and model specifics: A 2002 Dodge Neon's transmission system has specific components and their failure modes might differ slightly from other years.
Without the additional codes accompanying the P0700, any advice on a specific fix is purely speculation and could lead to unnecessary repairs. Get those codes read first!
