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Error Code P070D is defined as Transmission Fluid Level Sensor Circuit High. This is a generic but uncommon trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made since 1996 up to present. This code normally appears to Chevrolet, Dodge, Ford, GM, Ram, Hyundai, Toyota, etc. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
The TFL (transmission fluid level) sensor works by illuminating the warning light on the dash in case of low fluid level. If the fluid level is within the acceptable range, the switch is grounded. However, if the fluid drops lower than the predetermined level, the switch will open and cause a “low transmission level” condition, which will light up the light on the dash.
This sensor gets its reference voltage from the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes). The PCM monitors the circuit, and when it sees the switch is opened, it will turn on the low fluid warning on the instrument cluster.
Error Code P070D is set when the PCM detects a high transmission fluid level sensor signal, which usually indicates an open circuit problem.
Other related TRL error codes include:
- Check engine light on
- Transmission fluid warning light on
- Transmission performance issues
Multiple factors lead to this code, such as:
- Failed PCM
- Failed TCM
- Transmission fluid level sensor failure
- Wiring problem
How to Check
Start the diagnosis by checking the condition and level of the transmission fluid; it must be in accordance with the manufacturer’s recommendation. Then, check the transmission fluid level sensor and its corresponding wiring. Check for signs of damage or loose connections in the wiring. Any damages must be repaired. Clear the codes and see if it returns.
Then, check the problem with the TSB (technical service bulletin). If you can’t find anything, then move forward in your diagnosis.
The next steps are generalized procedure acceptable for most vehicles. To diagnose your problem more accurately, refer to your vehicle’s diagnostic flow chart.
Determine which wires are which by consulting with the factory wiring diagram. Many websites online offer free online repair manuals for many vehicles, you can check with them.
Reference Voltage Circuit Side Check
With ignition on, set the DVOM (digital volt ohmmeter) at DC volts and use it to check for reference voltage (usually 5 or 12V) from the PCM. To do this, connect the negative meter lead to the ground, and connect the positive meter lead to the sensor B+ terminal on the harness side of the connector. If there is no reference signal present, then connect the meter set to ohms (with the ignition off) between reference voltage pin on the TFL and the reference voltage pin on the PCM. If reference voltage reads out OL (out of limits), that means there’s an open circuit between the sensor and the PCM. You need to locate this open circuit and fix it. If the meter shows a numeric value, then there’s continuity.
If everything seems reasonable at this point, check the power that comes out of the PCM. Turn the ignition on and then set the meter at DC volts. Connect the positive meter lead to the reference voltage terminal on the PCM, and the negative lead to the ground. If there’s no reference voltage from PCM, that means the PCM is defective. However, this is rarely the case, so it’s a good idea to double check.
Circuit’s Ground Side Check
With ignition off, set the DVOM at ohms and use it to check for continuity by connecting the meter between the chassis ground and transmission fluid level sensor. If the meter shows a numeric value, then there’s continuity. If the meter shows OL, then there’s an open circuit problem between the PCM and the sensor. Locate it and repair as soon as possible.
If everything is good up to this point, and the problem persists, then the sensor must be faulty. To check the sensor, turn off the ignition and set the multimeter at ohms. Remove transmission fluid level sensor connector and connect the meter to the sensor terminals. If the meter shows OL, then there’s an open internally, and the sensor must be replaced.
How to Fix
- Filling of transmission fluid to the right level
- Replacement of transmission fluid level sensor
- Repair or replacement of defective connectors or wirings
- Replacement of defective PCM
The severity of this error code varies from moderate to severe. In some cases, the problem could result from as simple as low transmission fluid level, but when left unattained, this could result in serious transmission damage. Thus, this code must be diagnosed and fixed as soon as possible.