|Code||Fault Location||Probable Cause|
|P0990|| Transmission fluid pressure (TFP) sensor E -circuit high |
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|Wiring, short to positive, TFP sensor, ECM/PCM/TCM|
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What Does Code P0990 Mean?
Modern transmissions use transmission fluid pressure beyond just changing gears. Shifts between gears can be made more aggressively or smoothly depending on the driver’s habits. These adaptive shifts are also controlled with transmission fluid pressure by switches inside the transmission. Each adaptive pressure switch controls the harshness of gear changes in a predetermined set of gears which can vary depending on the manufacturer. Typically, transmission fluid pressure sensor E, or TFP sensor E will control higher range shift points such as 4-5-6 shifts.
These TFP sensors are integrated into control solenoid valve assemblies in many cases, though it’s possible that TFP sensors are loated on the valve body as well. TFP sensor E has an internal case ground and its normal position is closed, or low. The transmission control module (TCM) supplies a signal circuit to the TFP sensor E. When oil pressure is present at TFP sensor E, the switch is open or high. The sensor signal is used to help the TCM control the clutch regulator valve for the gears it controls, adapting the transmission shifts to the TCM’s logic according to learned driver behaviors.
DTC P0990 will set if the signal circuit to the TFP sensor E has high resistance as determined by the TCM.
DTC P0990 will set under certain conditions:
- The engine must be running
- Ignition voltage needs to be greater than 9.0 volts
- Transmission fluid temperature must be within -7C and +110C
- The TCM counts 30 instances of failure
What are the common causes of code P0990 ?
- Short to voltage or open circuit caused by rodent damage
- TCM internal failure
- Transmission fluid pressure sensor E failure
- Poor signal circuit due to break or corrosion
What are the symptoms of code P0990 ?
- Check Engine Light illuminated with DTC P0990
- Typically, no symptoms are noted at first as the TFP sensor only performs adaptive shift functions
- Harsh transmission shifts
- Sloppy or late transmission shifts
How do you troubleshoot code P0990 ?
To diagnose the transmission fluid pressure sensor E, you can use either a scan tool with the ability to monitor transmission sensor values, or a 12V test light will be sufficient if a scan tool is not available. Also, you’ll need a diagnostic chart of your TFP sensor positions during operation and a TCM to transmission wiring diagram which you might be able to obtain from your dealer or from a local parts store.
If you have a scan tool, you can monitor the TFP sensors while shifting through the gears. Plug the scan tool into the OBD data port and navigate to live monitoring. Locate your TFP sensors in the listing, particularly Sensor E. Your scan tool may refer to it as Sensor 5 as well.
With your engine running, the parking brake set and the wheels chocked, move your gear shifter through the range of gears. Compare the value of TFP sensor E with the values listed on the diagnostic chart, ensuring the switch changes from Low to High when necessary, then back to Low in the proper gear ranges.
If the value changes as it should, you may have been experiencing an intermittent code caused by dirt in the transmission fluid. You might also have an intermittent short to positive which may prove difficult to find. Diagnose intermittent faults with a test light while checking wiring and TCM signal output.
12V Test Light
At the transmission, locate the signal circuit for TFP sensor E. While the engine is running, the parking brake is set and the wheels are chocked, have an assistant engage the transmission into gear while you monitor your test light. When the signal circuit should be LOW, your test light should not be illuminated, and when your signal circuit should be HIGH, the test light should be bright.
- If the test light does not illuminate at all, you likely have an open in the circuit or a failed TFP sensor E. Trace the wiring from the TCM to the transmission, checking for breaks in the wire, corrosion, or loose connections at connectors. Perform a wiggle test on the wire as you trace it back while engaged in a gear where the sensor signal should be high, noting if the test light illuminates. Repair any problem areas and retest. If the problem still exists, replace TFP sensor E or the solenoid valve it is a part of.
- If the test light is illuminated while the circuit should be LOW voltage, you likely have short to voltage or a TCM failure. Trace the signal wire from the transmission back to the TCM, repairing corrosion, breaks, or shorts as necessary. Test the corresponding pin on the TCM for signal voltage. If there is signal voltage while in a gear where there should not be voltage, replace the TCM.
Codes Related to P0990
- P0987 – Transmission fluid pressure (TFP) sensor / switch E circuit malfunction