Recently my friend took complete motor and transmission from an old car to his Chevrolet Impala as the harness and PCM on his Impala was damaged. Then he got 2 P1810 codes. He tried to clear the codes with
GM Tech2 diagnostic scanner but the codes returned after 2-3 engine starts, or after sitting for while. Then he came to me for help.
DTC P1810 indicates to (Transmission Fluid Pressure) TFP Valve Switch Malfunction, which means there could be problems related to TFP valve switch. To find out the issue, let us have a look at the TFP valve switch circuit and PCM description:
The automatic transmission fluid pressure (TFP) manual valve position switch consists of five pressure switches (two normally-closed and three normally-open) and a transmission fluid temperature (TFT) sensor combined into one unit. The combined unit mounts on the valve body.
The powertrain control module (PCM) supplies ignition voltage for each range signal. By grounding one or more of the circuits through various combinations of the pressure switches, the PCM detects which manual valve position you select. The PCM 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 cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical. With the engine OFF and the ignition switch in the RUN position, the TFP manual valve position switch indicates PARK or NEUTRAL. Disconnecting the AT inline 20-way connector removes the ground potential for the three range signals to the PCM. In this case, with the engine OFF, and the ignition switch in the RUN position, D2 will be indicated.
When 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 B DTC.
The P1810 error code usually comes up in several situations:
No VSS assembly DTCs P0502 or P0503.
The system voltage is 8-18 volts.
The engine speed is greater than 450 RPM for 5 seconds.
The engine is not in fuel cutoff.
The engine torque is 50-450 lb ft.
The engine vacuum is 0-105 kPa.
Now let us go down to business and find out how to fix the P1810 problem.
First of all, per0form Powertrain Diagnostic System check.
Then go to a Powertrain On Board Diagnostic (OBD) System Check in Engine Controls.
Check transmission fluid level.
Take out
GM Tech2 scanner.
Turn ON the car ignition, with the engine OFF.
Record the DTC Freeze Frame and Failure Records.
Clear the DTC. Before clearing the DTC, use the
obd2 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.
Start the engine and idle at normal operating temperature.
Apply the brake pedal.
Select each transmission range: P, R, N, D4, D3, D2 and D1.
Does each selected transmission range match the Scan Tool TFP Sw.
Go to Diagnostic Aids
Turn OFF the ignition.
Disconnect the AT inline 20-way connector (additional DTCs may set).
Turn ON the ignition, with the engine OFF.
Does the Scan Tool TFP Sw. A/B/C parameter indicates HI for all range signal states?
Turn OFF the ignition.
Install the J 44152 jumper harness (20 pins) on the engine side of the AT inline 20-way connector.
Turn ON the ignition, with the engine OFF.
Using the J 39200 digital multimeter (DMM) and the J 35616-A connector test adapter kit, measure the voltage from terminal N of the J 44152 to ground. Refer to Automatic Transmission Inline Harness Connector End View.
Measure the voltage from terminal R of the J 44152 to ground.
Measure the voltage from terminal P of the J 44152 to ground.
Connect a fused jumper wire from terminal N of the J 44152 (signal circuit A) to ground while monitoring the Scan Tool TFP Sw. A/B/C parameter. When signal circuit A (CKT 1224) is grounded, do any other signal circuits indicate LOW?
Connect a fused jumper wire from terminal R of the J 44152 (signal circuit B) to ground while monitoring the Scan Tool TFP Sw. A/B/C parameter. When signal circuit B (CKT 1225) is grounded, do any other signal circuits indicate LOW?
Connect a fused jumper wire from terminal P of the J 44152 (signal circuit C) to ground while monitoring the Scan Tool TFP Sw. A/B/C parameter. When signal circuit C (CKT 1226) is grounded, do any other signal circuits indicate LOW?
Test the signal circuits (CKTs 1224, 1225 and 1226) of the TFP manual valve position switch that did not indicate HI for a short to ground between the PCM connector C1 and C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Repairs. Did you find and correct the condition?
Test the signal circuits (CKTs 1224, 1225 and 1226) of the TFP manual valve position switch that did not indicate ignition voltage for an open between the PCM connector C1 and C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Repairs. Did you find and correct the condition?
Test the affected signal circuits of the TFP manual valve position switch for a shorted together condition between the PCM connector C1 and C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Repairs. Did you find and correct the condition?
Test the signal circuits (CKTs 1224, 1225 and 1226) of the TFP manual valve position switch for an open or shorted condition between the TFP manual valve position switch and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Repairs. Did you find a condition?
Replace the AT wiring harness assembly. Refer to Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid, TCC Solenoid, and Wiring Harness. Did you complete the replacement?
Replace the TFP manual valve position switch. Refer to Valve Body and Pressure Switch
Replace the PCM. Refer to PCM Replacement/Programming in Engine Controls. Did you complete the replacement?
Perform the following procedure in order to verify the repair:
Select DTC.
Select Clear Info.
Operate the vehicle under the following conditions:
A. Turn ON the ignition, with the engine OFF for at least 2 seconds.
B. Start the vehicle and idle for 5 seconds.
C. Drive in D4 until the TCC locks for 10 seconds.
D. Continue to run the engine for at least 60 seconds from startup.