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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 HHR 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC P1810, 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 Descriptors

DTC P1810: Transmission Fluid Pressure (TFP) Position Switch Circuit

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

TFP Switch Signal B

P1810, P1816, P1818

P1816

--

TFP Switch Signal C

P1810, P1816, P1818

P1810, P1816, P1818

--

Typical Scan Tool Data

Scan Tool Parameter Data

Circuits

Normal

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Engine running, normal operating temperature

Parameter Normal Range: HI/HI

TFP Sig B.

HI/HI

LOW/HI

HI/HI

HI/HI

TFP Sig C.

HI/HI

HI/LOW

HI/HI

HI/HI

Circuit/System Description

The automatic transmission fluid pressure (TFP) manual valve position switch consists of three 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. The TFP manual valve position switch also contains the automatic transmission fluid temperature (TFT) sensor. These components are combined into one unit, attached to the control valve body. The transmission control module (TCM) provides battery voltage on the two range signal circuits. By grounding one or more of the switches with fluid pressure from the manual shift valve, the TCM detects the selected gear range. When you disconnect the transmission electrical connector and the ignition is ON, the ground potential for the range signals from the TCM will be removed, and an invalid gear range will be indicated. Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic .

Conditions for Running the DTC

P1810

The engine is running for 5 seconds.

P1816

    • No TP DTCs P0120 or P0220.
    • No ISS DTCs P0716 or P0717.
    • No OSS DTCs P0722 or P0723.
    • No SS valve performance DTCs P0751, P0752, P0756, or P0757.
    • No SS valve electrical DTCs P0973 or P0974, P0976, or P0977.
    • The engine is running for 5 seconds.
    • The Calc. Throttle Position is between 8 percent and 90 percent.
    • The engine torque is greater than 50 N·m (37 lb ft).
    • The output speed is 250 RPM or more.

P1818

    • No MAP DTCs P0107 or P0108.
    • No TP DTCs P0120 or P0220.
    • No ISS DTCs P0716 or P0717.
    • No OSS DTCs P0722 or P0723.
    • No SS valve performance DTCs P0751, P0752, P0756, or P0757.
    • No SS valve electrical DTCs P0973 or P0974, P0976, or P0977.
    • The engine is running for 5 seconds.
    • The Calc. Throttle Position is 3 percent or more.
    • The engine torque is greater than 20 N·m (15 lb ft).
    • The output speed is 153 RPM or more.
    • The transmission fluid temperature is greater than 0°C (32°F).

Conditions for Setting the DTC

P1810

The TCM detects an invalid gear range for 60 seconds. Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic .

P1816

The TCM detects P/N with a drive ratio for 6 seconds.

P1818

The TCM detects a PARK, NEUTRAL, or a drive range with a REVERSE ratio for 3 seconds.

Action Taken When the DTC Sets
    • DTCs P1810, 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, P1816, and P1818 are Type B DTCs.

Diagnostic Aids

The following conditions may also be present if any of these DTCs set:

    • Disables auto door lock function
    • Disables Cruise Control
    • Disables the shift interlock

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

    •  Automatic Transmission Inline 20-Way Connector End View
    •  Automatic Transmission Internal Connector End Views
    •  Automatic Transmission Related Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

DTC Type Reference

    •  Diagnostic Trouble Code (DTC) Type Definitions
    •  Diagnostic Trouble Code (DTC) List/Type

Special Tools

    • J 35616 GM 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 Checking Procedure.
    2. ⇒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.
    3. ⇒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.
    4. ⇒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.
    5. ⇒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.
    6. ⇒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.
    7. ⇒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.
    8. ⇒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 and the J 35616 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.
    2. ⇒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.
    3. ⇒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 Replacement
    •  Control Module References for TCM replacement, setup, and programming