P1810

CIRCUIT DESCRIPTION

The Automatic Transmission Fluid Pressure Manual Valve Position switch (TFP Val. Position Sw.) consists of five normally open switches. Ignition voltage is applied to each of the switches. By grounding one or more of these switches with fluid pressure from the manual valve, the Powertrain Control Module (PCM) can detect which gear range is selected.

If the PCM detects an invalid combination of the TFP Val. Position Sw., then DTC P1810 sets. DTC P1810 is a Type B DTC.

CONDITIONS FOR SETTING THE DTC

^ No MAP DTCs P0101, P0102 or P0103 are set.
^ No Throttle Position (TP) sensor DTCs P0121, P0122 or P0123 are set.
^ No Vehicle Speed (VSS) sensor DTCs P0502 or P0503 are set.
^ No Automatic Transmission Input Speed (A/T ISS) sensor DTCs P0716 or P0717 are set.
^ Ignition voltage is 10-17 volts.
^ Engine running for more than 5 seconds.
^ Not in fuel cut off.

All of the above conditions must be true with any one of the following failure cases:

Case 1
An illegal TFP Val Position Sw. value of 000 or 010 exists for 4 seconds.

Case 2
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The throttle angle is greater than 11°.
^ The delivered torque is 109-270 Nm (80-200 lb ft).
^ The TFP Val. Position Sw. indicates P/N and the ratio indicates Reverse or Drive for 4 seconds.

Case 3
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The throttle angle is greater than 11°.
^ The delivered torque is 109-270 Nm (80-200 lb ft).
^ The TFP Val. Position Sw. indicates Reverse and the ratio indicates Drive for 4 seconds.

Case 4
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The throttle angle is greater than 7°.
^ The delivered torque is 38-188 Nm (30-150 lb ft).
^ The TFP Val. Position Sw. indicates D4, D3, D2 or D1 and the ratio Indicates Reverse for 3 seconds.

Case 5
^ The engine is OFF.
^ The TFP Val. Position Sw. indicates D2 initially and does not indicate P/N within 4.95 seconds after the engine is running.
^ Discontinue case #5 if the engine is running for 5 seconds.
^ The vehicle speed is less than 8 km/h (5 mph).
^ The Transmission Fluid Temperature is greater than -18°C (0°F).

ACTION TAKEN WHEN THE DTC SETS

^ The PCM illuminates the Malfunction Indicator Lamp (MIL) after two consecutive trips with a failure reported.
^ SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on the Driver Information Center (DIC).
^ The PCM substitutes the value of the previous TFP Val. Position Sw. if it is consistent with the Park/Neutral status.
^ The PCM commands default line pressure.
^ The PCM disables steady state adapts.
^ The PCM disables garage shift adapts.
^ The PCM inhibits Torque Converter Clutch.
^ The PCM inhibits torque management.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS

^ Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Inspect the wiring for poor electrical connections at the 3-way TFP Val. Position Sw. connector. Look for the following problems:

- A bent terminal
- A backed out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire

^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
^ If a transmission overhaul was performed, ensure that the transmission fluid is at the proper level. A low fluid problem may set this DTC.
^ Diagnose DTC 1520 first, if set.
^ Inspect the TFP Val. Position Sw. for debris.

TEST DESCRIPTION

The numbers below refer to the step numbers on the diagnostic table.

2. This step ensures that you verify the transmission fluid level, and that the fluid is at the proper level.

Important: The scan tool display indicates ON and OFF:

ON = Switch is Closed
OFF = Switch is Open

3. This step isolates the Automatic Transmission Wiring Harness from the Engine Wiring Harness. If the scan tool display does not match the value column, the source of the DTC may be in the Engine Wiring Harness.
10. This step verifies that circuit 1224 and circuit 1225 of the Engine Wiring Harness are shorted together and shorted to ground.
12. This step verifies that circuit 1224 and circuit 1226 of the Engine Wiring Harness are shorted together and shorted to ground.
14. This step verifies that circuit 1225 and circuit 1226 of the Engine Wiring Harness are shorted together and shorted to ground.
17. This step uses the Jumper Harness in order to test the Engine Wiring Harness circuits. With this step, the scan tool displays a good circuit 1224.
20. This step verifies that circuit 1224 and circuit 1225 of the Engine Wiring Harness are shorted together.
26. This step verifies that circuit 1225 and circuit 1226 of the Engine Wiring Harness are shorted together.
30. This step uses the jumper harness in order to test the Automatic Transmission Wiring Harness. If the ohmmeter display does not match the value column, then either the Automatic Transmission Wiring Harness or the TFP Val. Position Sw Assembly is the source of the DTC. One ohmmeter probe is connected to terminal N of the Automatic Transmission Wiring Harness. The other ohmmeter probe is then connected to the transmission case. This step determines whether circuit 1224 is faulty.
36. The engine is running so that transmission fluid is applied to the pressure switches. The ohmmeter verifies that the Automatic Transmission Wiring Harness circuits are open. This step verifies that circuit 1224 is faulty.