P1809
DTC P1808 or P1809
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P1808
- Transmission Fluid Pressure (TFP) Position Switch - Stuck Off
DTC P1809
- Transmission Fluid Pressure (TFP) Position Switch - Stuck On
Circuit/System Description
Note: MY 2008 and 2009 Transmission models 9BAJ and 9BBJ have a normally open pressure switch A.
MY 2009 Transmission models 9CCJ and 9DAJ have a normally closed pressure switch A.
The automatic transmission fluid pressure (TFP) manual valve position switch consists of four pressure switches. Two of the switches are normally-open, and determine gear range selection. The third switch is normally-closed, and detects torque converter clutch (TCC) release fluid pressure. A fourth switch may be normally open or normally closed, depending on the transmission model, and is used to determine if the transmission has line pressure for Hybrid operation. The TFP manual valve position switch also contains the automatic transmission fluid temperature (TFT) sensor. These components are combined into one unit that is attached to the control valve body.
The transmission control module (TCM) provides a reference voltage on the two range signal circuits. By grounding one or more of switches B and C with fluid pressure from the manual shift valve, the TCM detects the selected gear range. Switch A indicates to the engine control module (ECM) if there is line pressure, from either the transmission or the auxiliary transmission pump, which allows hybrid operation.
Conditions for Running the DTC
Calibrated For a Normally-Open TFP Switch A:
P1808
* No CKP DTCs P0335 or P0336.
* The engine is running for 5 seconds.
P1809
* The engine has not been running for 5.5 seconds.
* The vehicle speed is 0 km/h (0 mph).
Calibrated For a Normally-Closed TFP Switch A:
P1808
* The engine has not been running for 5.5 seconds.
* The vehicle speed is 0 km/h (0 mph).
P1809
* No CKP DTCs P0335 or P0336.
* The engine is running for 5 seconds.
Conditions for Setting the DTC
P1808
The ECM determines that the TFP signal A circuit is open or stuck OFF.
P1809
The ECM determines that the TFP signal A circuit is shorted to ground or stuck ON.
Action Taken When the DTC Sets
* DTCs P1808 and P1809 are Type B DTCs.
* The ECM Inhibits Hybrid Operation.
Conditions for Clearing the DTC
DTCs P1808 and P1809 are Type B DTCs.
Diagnostic Aids
Installing an incorrect TFP manual valve position switch will cause both DTC P1808 and P1809 to set.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (4T45-E - Automatic Transmission)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Electronic Component Description (Electronic Component Description) for automatic transmission fluid pressure manual valve position switch assembly information.
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
J 44152 Jumper Harness (20 pins)
Circuit/System Verification
1. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check).
2. Ignition ON, engine off, gear selector in Park, Reverse, Neutral, or Drive, observe the scan tool ECM TFP switch A parameter should read Low. Engine running, observe the scan tool ECM TFP switch A parameter should read High.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observe from the Freeze Frame/Failure Records data.
Circuit/System Testing
Important: If the above Circuit/System Verification results in inverted operation, check for a calibration/switch mismatch.
Important: Additional DTCs may set when disconnecting the automatic transmission inline 20-way connector.
Normally-Open TFP Switch A:
1. Ignition OFF, disconnect the AT 20-way inline harness connector at the transmission.
2. Ignition ON, verify the scan tool ECM TFP Switch A parameter is Low.
• If not the specified value, test the signal circuit terminal N for a short to ground. If the circuit tests normal, replace the ECM.
3. Install a 3A fused jumper wire between the signal circuit terminal N to ground. Verify the scan tool TFP Switch A is High.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
4. Test for less than 1 ohm of resistance between terminal N of the AT 20-way connector and terminal A of the TFP manual valve position switch.
• If greater than the specified range, replace the Internal Transmission Harness.
5. If all circuits test normal, test or replace the TFP switch.
Normally-Closed TFP Switch A:
1. Ignition OFF, disconnect the AT 20-way inline harness connector at the transmission.
2. Ignition ON, verify the scan tool ECM TFP Switch A parameter is High.
• If not the specified value, test the signal circuit terminal N for a short to ground. If the circuit tests normal, replace the ECM.
3. Install a 3A fused jumper wire between the signal circuit terminal N to ground. Verify the scan tool TFP Switch A is Low.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
4. Test for less than 1 ohm of resistance between terminal N of the AT 20-way connector and terminal A of the TFP manual valve position switch.
• If greater than the specified range, replace the Internal Transmission Harness.
5. If all circuits test normal, test or replace the TFP switch.
Component Testing
Normally-Open TFP Switch A:
With the TFP switch removed from the transmission test for infinite resistance between the control terminal A and the metal mounting bracket of the TFP switch, and less than 5 ohms of resistance while depressing the switch.
If not within the specified range, replace the TFP Switch.
Normally-Closed TFP Switch A:
With the TFP switch removed from the transmission test for less than 5 ohms of resistance between the control terminal A and the metal mounting bracket of the TFP switch, and infinite resistance while depressing the switch.
If not within the specified range, replace the TFP Switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
* Control Module References (Programming and Relearning) for ECM replacement, setup, and reprogramming