P1816
DTC P1810, P1815, P1816, or P1818
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P1810
- Transmission Fluid Pressure (TFP) Position Switch Circuit
DTC P1815
- Transmission Fluid Pressure (TFP) Valve Position Switch - Start in Wrong Range
DTC P1816
- Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Park/Neutral (P/N) with Drive Ratio
DTC P1818
- Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Drive without Drive Ratio
Circuit/System Description
The automatic transmission fluid pressure (TFP) manual valve position switch consists of 5 pressure switches and a transmission fluid temperature (TFT) sensor combined into one unit. The combined unit mounts on the valve body. The transmission control module (TCM) supplies ignition voltage for each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the TCM detects which manual valve position you select. The TCM compares the actual voltage combination of the switches to a TFP manual valve position switch combination chart stored in memory.
The TFP manual valve position switch cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical. With the engine OFF and the ignition switch in the ON position, the TFP manual valve position switch indicates PARK/NEUTRAL. Disconnecting the AT inline 20-way connector removes the ground potential for the 3 range signals to the TCM. In this case, with the engine OFF, and the ignition switch in the ON position, D2 will be indicated.
Conditions for Running the DTC
P1810
The engine speed is greater than 500 RPM for 5 seconds.
P1815
* No output speed sensor (OSS) DTCs P0722, or P0723.
* The system voltage is 8-18 volts.
* OSS speed is 250 RPM or less.
P1816
* No input speed sensor (ISS) DTCs P0716 or P0717.
* No OSS DTCs P0722, or P0723.
* No SS DTCs P0751, P0752, P0756, P0757, P0973, P0974, P0976 or P0977.
* No TFP DTCs P1810, P1815 or P1818.
* The engine torque is greater than 50 N.m (37 lb ft).
* The output speed is 350 RPM or greater.
* OSS speed is 350 RPM or greater.
* The throttle position is 8 percent or greater.
P1818
* No OSS DTCs P0722, or P0723.
* No TFP DTCs P1810, P1815 or P1816.
* The throttle position is 8 percent or greater.
* The engine torque is 20 N.m (15 lb ft) or greater.
* OSS speed is 50 RPM or greater.
Conditions for Setting the DTC
P1810
The TCM detects an invalid TFP manual valve position switch state for 60 seconds.
P1815
The TCM detects D2 only, TFP manual valve position switch state during and after engine start for 3.25 seconds.
P1816
The TCM detects one of the following conditions for 6 seconds.
* PARK/NEUTRAL indicated with a 1st gear ratio.
* PARK/NEUTRAL indicated with a 2nd gear ratio.
* PARK/NEUTRAL indicated with a 3rd gear ratio.
* PARK/NEUTRAL indicated with a 4th gear ratio.
P1818
The TCM detects the following condition for 5 seconds.
PARK/NEUTRAL or FORWARD range indicated with a reverse gear ratio.
Action Taken When the DTC Sets
* DTCs P1810, P1815, P1816 and P1818 are Type B DTCs.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
Conditions for Clearing the DTC
DTCs P1810, P1815, P1816, P1818 are Type B DTCs.
Diagnostic Aids
* Refer to the Transmission Fluid Pressure Manual Valve Position Switch Logic (Transmission Fluid Pressure Manual Valve Position Switch Logic) for the normal range signals and the invalid combinations. On the table, LOW is 0 volts, HI is ignition voltage.
* Sediment in the valve body may cause improper operation of the TFP manual valve position switch. If sediment intrusion is suspected, clean the valve body and replace the TFP manual valve position switch.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (4.2L) (Electrical Diagrams)Automatic Transmission Controls Schematics (5.3L/6.0L) (Electrical Diagrams)
Connector End View Reference
Component Connector End Views
Description and Operation
Transmission General Information (Transmission General Information)
Electrical Information Reference
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Transmission Control Module Scan Tool Information
Special Tools
* J 35616 GM-Approved Terminal Test Kit
* J 44152 Jumper Harness (20 Pins)
Circuit/System Verification
Start and idle the engine. Using the scan tool, observe the TFP Sig. B/Sig. C parameter. The scan tool should display HI/HI. Move the gear selector through all ranges and ensure that the TFP Switch parameter matches the gear selector for each selected range.
Circuit/System Testing
1. Perform the Transmission Fluid Check (Testing and Inspection) .
• If the fluid level is at an incorrect level, repair any leaks found and add fluid to the proper level.
2. Disconnect the AT inline 20-way connector. Turn ON the ignition with the engine OFF. Observe the TFP Sig. B/Sig. C parameter on the scan tool. The parameter should display HI/HI.
• If the TFP Sig. B/Sig. C parameter does not display HI/HI, repair the short to ground in the TFP signal circuit that displayed LOW.
3. Using a DMM, measure the voltage at the engine side of the AT 20-way connector between the TFP signal B circuit and ground and the TFP signal C circuit and ground. The voltage should be near 12 volts for each circuit.
• If the voltage is less than the specified range, test the affected circuit for an open.
4. Turn OFF the ignition. Measure the resistance at the transmission side of the AT 20-way connector between the TFP signal B circuit and the transmission case. The resistance should be greater than 10K ohms.
• If the resistance is less than 10K ohms, test the TFP signal B circuit for a short to ground.
5. Measure the resistance at the transmission side of the AT 20-way connector between the TFP signal C circuit and the transmission case. The resistance should be greater than 10K ohms.
• If the resistance is less than 10K ohms, test the TFP signal C circuit for a short to ground.
6. Measure the resistance of the TFP signal B circuit between the transmission side of the AT 20-way connector and the TFP switch. The resistance should be less than 10 ohms.
• If the resistance is greater than 10 ohms repair the open in the TFP signal B circuit.
7. Measure the resistance of the TFP signal C circuit between the transmission side of the AT 20-way connector and the TFP switch. The resistance should be less than 10 ohms.
• If the resistance is greater than 10 ohms repair the open in the TFP signal C circuit.
• If all circuits/connections test normal, replace the TCM.
Component Testing
1. Disconnect the AT 20-way connector. Using the J 44152 jumper harness (20 Pins), and the J 35616 GM-approved terminal test kit, measure the resistance between the TFP signal B circuit and the TFP signal C circuit at the transmission side of the AT 20-way connector and ground. The resistance should be greater than 10K ohms.
• If the resistance is not greater than the specified range, test the affected circuit for a short to ground.
• If a short to ground is not found, replace the TFP switch.
2. Start the engine. Measure the resistance between the TFP signal B circuit and the TFP signal C circuit at the transmission side of the AT 20-way connector and ground. The resistance should be less than 10 ohms.
• If the resistance is greater than 10 ohms, test the affected circuit for an open.
• If an open circuit is not found, replace the TFP switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
* Transmission Fluid Pressure Manual Valve Position Switch Logic (Transmission Fluid Pressure Manual Valve Position Switch Logic)
* Refer to Control Module References for TCM replacement, setup, and programming