P1811

Diagnostic Chart:

Description:

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) compares the measured gear ratio to the known actual value. This allows the PCM to determine the actual gear range of the transmission. When an upshift is commanded, the PCM measures the interval during which the gear ratio leaves the current range and changes to reflect the commanded upshift. This interval is expressed on the scan tool as Shift Time. When this interval has exceeded a predetermined limit, the PCM utilizes the shift adapts in order to attempt to shorten the shift time.
If the PCM detects that the maximum allowable shift time has been exceeded, and that the upshift adapts have reached their upper limit, then DTC P1811 sets. DTC P1811 is a type D DTC.

CONDITIONS FOR SETTING THE DTC
^ The engine must be running at greater than 475 RPM for more than 7 seconds.
^ One of the following conditions exists, with the adapt cells at the maximum pressure allowed for 5 consecutive occurrences of one shift.
- The 1-2 or the 2-3 upshifts are greater than 1.25 seconds.
- The 3-4 upshifts are greater than 6.38 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM freezes shift adapts.
^ The PCM commands maximum line pressure.

CONDITIONS FOR CLEARING THE DTC
^ 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. Look 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.
^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
^ DTC P1811 can be caused by a faulty turbocharger or wastegate assembly. If no other symptoms are present, check the turbocharger system for proper operation.
^ Ask the customer about overloading the vehicle exceeding the trailer-towing limit, or towing in Overdrive.
^ If, after several unsuccessful attempts to gain accurate shift times, and an adapt can be made, reset adapts and operate the vehicle, in order to assure proper shifting.
^ While driving the vehicle, inspect for loss of power, misfire, or other engine related driving conditions.

TEST DESCRIPTION
2. This step tests for low fluid level, which can cause delayed shifts.
3. This step compares the indicated range signal from the Range Signal table to the Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) selected gear range.
5. This step tests for low line pressure, which can cause delayed and long shifts.