4L60-E / 4L65-E Automatic Transmission

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

Circuit Description with 4L60-E / 4L65-E Automatic Transmission
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 Vehicle Control Module (VCM) supplies ignition voltage for each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the VCM detects which manual valve position you select. The VCM 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/NEUTRAL. Disconnecting the AT inline 20-way connector removes the ground potential for the three range signals to the VCM. In this case, with the engine OFF, and the ignition switch in the RUN position D2 will be indicated.

When the VCM 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.

CONDITIONS FOR RUNNING THE DTC
^ No VSS assembly DTCs P0502 or P0503.
^ The system voltage is 10-19 volts.
^ The engine speed is greater than 450 RPM for 5 seconds.
^ The engine is not in fuel cutoff.
^ The engine torque is 40-400 lb ft.
^ The engine vacuum is 0-105 kPa.

CONDITIONS FOR SETTING THE DTC

DTC P1810 sets if any of the following conditions occurs:

Condition 1
The VCM detects an illegal TFP manual valve position switch state for 60 seconds.

Condition 2
^ The engine speed is less than 80 RPM for 0.1 second; then the engine speed is 80-550 RPM for 0.1 second; then the engine speed is greater than 550 RPM.
^ The vehicle speed is less than 3 km/h (2 mph).
^ The VCM detects a gear range of D2, D4 or REVERSE during an engine start.
^ All conditions met for 5 seconds.

Condition 3
^ The TP angle is 10-50%.
^ The VCM commands fourth gear.
^ The TCC is locked ON.
^ The speed ratio is 0.6-0.75 (speed ratio is engine speed divided by transmission output speed).
^ The VCM detects a gear range of PARK or NEUTRAL when the vehicle is operating in D4.
^ All conditions met for 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The VCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The VCM commands D2 line pressure.
^ The VCM commands a D4 shift pattern.
^ The VCM freezes shift adapts from being updated.
^ The VCM records the operating conditions when the Conditions for Setting the DTC are met. The VCM stores this information as Freeze Frame and Failure Records.
^ The VCM stores DTC P1810 in VCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The VCM 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.
^ The VCM clears the DTC from VCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The VCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the VCM.

DIAGNOSTIC AIDS
^ Refer to the Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic table for the normal range signals and the invalid combinations. On the table, LOW is 0 volts, HI is ignition voltage.
^ Inspect the wiring at the VCM, 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 condition, massage the wiring harness while watching the test equipment for a change.
^ Sediment in the valve body may cause improper operation of the TFP manual valve position switch. If sediment intrusion is suspected, clean the valve body and replace the TFP manual valve position switch.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step compares the indicated range signal to the selected manual valve position.
5. This step tests for correct voltage from the VCM to the AT inline 20-way connector.