| Table 1: | TFP Valve Position Switch Logic Table |
| Table 2: | DTC P1810 TFP Manual Valve Position Switch Assembly Circuit Malfunction |
Circuit Description
The Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) consists of six pressure switches. Five of the switches are normally-open, and determine gear range selection. The sixth switch is normally-closed, and detects Torque Converter Clutch (TCC) release fluid pressure. The TFP Val. Position Sw. also contains the Automatic Transmission Fluid Temperature (TFT) sensor. These components are combined into one unit, mounted on the valve body.
The Powertrain Control Module (PCM) provides battery voltage on the three range signal circuits. By grounding one or more of the switches with fluid pressure from the manual shift valve, the PCM detects the selected gear range. When you disconnect the transmission electrical connector and the ignition is ON, the ground potential for three range signals from the PCM will be removed, and an illegal gear will be indicated (Refer to the TFP Valve Position Switch Logic Table).
When the PCM detects any of the following conditions, DTC P1810 sets.
| • | An invalid gear state |
| • | A drive range after start up |
| • | An incorrect gear ratio |
DTC P1810 is a type B DTC.
Conditions for Setting the DTC
DTC P1810 sets when any one of the following three conditions occurs:
Condition 1
| • | The engine is running. |
| • | The gear range is illegal for 60 seconds (Refer to the TFP Valve Position Switch Logic Table). |
Condition 2
| • | No VSS DTCs P0502 or P0503. |
| • | The engine speed is in transition from 0 RPM to greater than 600 RPM. |
| • | The vehicle speed is less than 3 km/h (2 mph). |
| • | D2, D4 or Reverse gear is indicated after start-up for 15 seconds. |
Condition 3
| • | No TP DTCs P0121, P0122, or P0123. |
| • | No VSS DTCs P0502 or P0503. |
| • | No A/T ISS DTCs P0716 or P0717. |
| • | No shift solenoid DTCs P0751, P0753, P0756 or P0758. |
| • | The engine is running. |
| • | The vehicle speed is at least 8 km/h (5 mph). |
| • | The TP is at least 10%. |
| • | Engine torque is greater than 13 N·m (10 lb ft). |
| • | The MAP is 10-105 kPa. |
| • | All of the above conditions occur and any one of the following three conditions occurs: |
| - | The TFP Val. Position Sw. indicates Park/Neutral when the gear ratio is less than 1:0.72 (4th gear) for 5 seconds. |
| - | The TFP Val. Position Sw. indicates Reverse when the gear ratio is greater than 1:2.23, or less than 1:2.02, for 5 seconds. |
| - | The TFP Val. Position Sw. indicates D4, D3, D2 or D1 when the gear ratio indicates Reverse for 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The PCM elevates line pressure. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM assumes a D4 shift pattern. |
| • | The PCM freezes shift adapts from being updated. |
| • | DTC P1810 is stored in the PCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive trips 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
| • | A pressure regulator problem could set DTC P1810. |
| • | Inspect the wiring for poor electrical connections at the PCM, the transmission 20-way connector and the TFP Val. Position Sw. 6-way connector for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change. |
Gear Position | Range Signal A | Range Signal B | Range Signal C |
|---|---|---|---|
PARK | ON | OFF | OFF |
REVERSE | ON | OFF | ON |
NEUTRAL | ON | OFF | OFF |
DRIVE/OD | ON | ON | OFF |
D3/3rd | OFF | ON | OFF |
D2/2nd | OFF | ON | ON |
D1/Lo | ON | ON | ON |
Illegal | OFF | OFF | OFF |
Illegal | OFF | OFF | ON |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the PCMs ability to recognize an open circuit on signal A, B, and C ranges.
-
This step verifies signal A circuit from the PCM.
-
This step verifies signal B circuit from the PCM.
-
This step verifies signal C circuit from the PCM.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
2 | Have you performed the transmission fluid checking procedure? | -- | Go to Transmission Fluid Check | |||||
3 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM. Refer to Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Logic Table. Does each selected transmission range match the scan tool display? | -- | Go to Diagnostic Aids | |||||
Does the TFP Switch display match the specified values? | A Off B Off C Off | |||||||
5 | Does TFP Switch indicate range signal A is On? | -- | ||||||
6 | Does TFP Switch indicate range signal B is On? | -- | ||||||
7 | Does TFP Switch indicate range signal C is On? | -- | -- | |||||
8 | Inspect circuit 1224 of the engine harness for a short to ground. Refer to General Electrical Diagnosis . Did you find and correct the condition? | -- | ||||||
9 | Inspect circuit 1225 of the engine harness for a short to ground. Refer to General Electrical Diagnosis . Did you find and correct the condition? | -- | ||||||
10 | Inspect circuit 1226 of the engine harness for a short to ground. Refer to General Electrical Diagnosis . Did you find and correct the condition? | -- | ||||||
|
Important: If, while performing steps 11, 12, or 13, two (or more) signal ranges indicate On, those circuits are shorted together.
Does the TFP Switch indicate signal A is On? | A On | |||||||
Connect the fused jumper wire from terminal R to a good ground. Does the TFP Switch indicate signal B is On? | B On | |||||||
Connect the fused jumper wire from terminal P to a good ground. Does the TFP Switch indicate signal C is On? | C On | |||||||
14 | Inspect circuit 1224 of the engine harness for an open. Refer to General Electrical Diagnosis . Did you find and correct the condition? | -- | ||||||
15 | Inspect circuit 1225 of the engine harness for an open. Refer to General Electrical Diagnosis . Did you find and correct the condition? | -- | ||||||
16 | Inspect circuit 1226 of the engine harness for an open. Refer to General Electrical Diagnosis . Did you find and correct the condition? | -- | ||||||
17 |
Is the resistance greater than the specified value? | 1000 ohms | ||||||
18 | Measure the resistance from terminal R to a good ground. Is the resistance greater than the specified value? | 1000 ohms | ||||||
19 | Measure the resistance from terminal P to a good ground. Is the resistance greater than the specified value? | 1000 ohms | ||||||
20 | Inspect circuit 1224, from the transmission 20-way connector to the TFP Val. Position Sw., for a short to ground. Refer to General Electrical Diagnosis . Did you find the condition? | -- | ||||||
21 | Inspect circuit 1225, from the transmission 20-way connector to the TFP Val. Position Sw., for a short to ground. Refer to General Electrical Diagnosis . Did you find the condition? | -- | ||||||
22 | Inspect circuit 1226, from the transmission 20-way connector to the TFP Val. Position Sw., for a short to ground. Refer to General Electrical Diagnosis . Did you find the condition? | -- | ||||||
23 | Inspect circuit 1224 from the transmission 20-way connector to the TFP Val. Position Sw. for an open. Refer to General Electrical Diagnosis . Did you find the condition? | -- | ||||||
24 | Inspect circuit 1225 from the transmission 20-way connector to the TFP Val. Position Sw. for an open. Refer to General Electrical Diagnosis . Did you find the condition? | -- | ||||||
25 | Inspect circuit 1226 from the transmission 20-way connector to the TFP Val. Position Sw. for an open. Refer to General Electrical Diagnosis . Did you find the condition? | -- | ||||||
26 | Replace the automatic transmission wiring harness. Refer to the Transmission Unit Repair Manual, 4T40-E Section. Is the replacement complete? | -- | -- | |||||
27 | Replace the TFP Val. Position Sw. Refer to the Transmission Unit Repair Manual, 4T40-E Section. Is the replacement complete? | -- | -- | |||||
28 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | -- | |||||
29 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
