Circuit Description
The automatic transmission fluid pressure (TFP) manual valve position switch consists of five normally-open pressure switches. The powertrain control module (PCM) supplies battery voltage to each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected, and compares the actual voltage combination of the switches to a TFP manual valve position switch combination table stored in memory.
The TFP manual valve position switch assembly cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical in both cases. With the ignition ON and the engine OFF, D2 is indicated. When the transmission 20-way connector is disconnected, the ground potential for the three range signals to the PCM is removed, and with the ignition ON, D2 is indicated.
If the PCM detects an invalid state of the TFP manual valve position switch circuit by deciphering the TFP manual valve position switch inputs, then DTC P1810 sets. DTC P1810 is a type D DTC. For California emissions vehicles DTC P1810 is a type B DTC.
Conditions for Running the DTC
| • | The system voltage is 8.0-16.0 volts. |
| • | The engine speed is greater than 300 RPM for 7 seconds. |
| • | No OSS DTCs P0502 or P0503. |
| • | No ISS DTCs P0716 or P0717. |
| • | No PSA DTC P1810. |
| • | No MAP DTCs P0106, P0107 or P0108. |
| • | No 1-2 SS DTCs P0751 or P0753. |
| • | No 2-3 SS DTCs P0756 or P0758. |
| • | Not in fuel cut off. |
| • | The engine torque is 108-540 N·m (80-400 lb ft). |
| • | The engine vacuum is 0-105 kPA. |
Conditions for Setting the DTC
DTC P1810 sets during the second consecutive trip in which any of the following condition occurs:
Condition 1
The PCM detects an illegal TFP manual valve position switch state for 60 seconds.
Condition 2
| • | The engine speed is less than 50 RPM for 0.3 second; then between 50 and 950 RPM for 0.3 second; then the engine speed is greater than 950 RPM. |
| • | The vehicle speed is less than 4 km/h (2.5 mph). |
| • | The PCM detects the gear range D1, D2 or REVERSE before and after start up. |
| • | All conditions are met for 7 seconds. |
Condition 3
| • | The vehicle speed is greater than 8 km/h (5 mph). |
| • | The TP angle is greater than 10%. |
| • | The PCM detects an invalid state of the PSA sensor or the PSA circuit. |
The TFP switch indicates the following:
| • | P/N when the ratio indicates less than 1.05:1 for greater than 15 seconds. |
| • | Reverse when the ratio indicates D4, D3, D2, and D1 for greater than 15 seconds. |
| • | D4, D3, D2, and D1 when the ratio indicates reverse for greater than 7 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp for California emission vehicles. |
| • | The PCM commands maximum line pressure. |
| • | The PCM assumes D4 for the PRNDL shift pattern. |
| • | The PCM freezes shift adapts. |
| • | The PCM commands the TCC on in commanded fourth gear. |
| • | The PCM stores DTC P1810 in PCM history. |
Conditions for Clearing the MIL/DTC
| • | For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool can clear the MIL/DTC. |
| • | For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring. |
| • | For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Refer to the accompanying table for the normal range signals and the illegal combinations. |
| • | Inspect the wiring at the PCM, the transmission connector and all other circuit connecting points for the following conditions: |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Reduced terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | DTC P1810 can be falsely set during a fluid fill procedure. After refilling the fluid, cycle key down then start and run the vehicle for 20 seconds. Key down and allow the PCM to power down, and then restart the vehicle. |
| • | DTC P1810 can be set falsely by low pump pressure or a stuck pressure regulator. |
| • | DTC P1810 can be set by a rolled forward clutch piston seal. It may allow the PCM to see a 2.08:1 ratio (reverse) when the manual valve position is indicated as D4. |
| • | First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
| • | Refer to the Range Signal table. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the indicated range signal to the manual valve that is actually selected.
-
This step tests the voltage from the PCM to the transmission 20-way connector.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||
2 |
Were the inspections performed? | -- | Go to Transmission Fluid Check | |||||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM. Does each selected transmission range match the scan tool TFP switch A/B/C display? (Refer to the Range Signal table.) | -- | Go to Diagnostic Aids | ||||||||||
Is B+ displayed on all three circuits? | -- | Go to Step 5 | ||||||||||
5 | Inspect the circuits that did not indicate B+ in Step 4 for an open or short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was an open or shorted to ground condition found? | -- | ||||||||||
6 | Verify that CKT 1224, CKT 1225, and CKT 1226 are not shorted together. Use a fused jumper wire in order to ground each circuit while monitoring the scan tool TFP switch display. When a range signal circuit is grounded, are any of the other range signal circuits affected? | -- | Go to Transmission Fluid Pressure Manual Valve Position Switch Resistance Check | |||||||||
7 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||||
8 | Repair the affected wiring as needed. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
