DTC P1811 Maximum Adapt and Long Shift Diesel Applications Only
| Table 1: | 4L80-E Range Reference, modified for DTCs P1870 & P1871 |
| Table 2: | DTC P1811 Maximum Adapt-Long Shift Time |
Range | Gear | 1-2 Sol | 2-3 Sol | Fourth Clutch | Overrun Clutch | O/D Roller Clutch | FWD Clutch | Direct Clutch | Front Band | Interm. Sprag Clutch | Interm Clutch | Lo Roller Clutch | Rear Band |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Overdrive | 1st | On | Off | -- | -- | H | A | -- | -- | * | -- | H | -- |
2nd | Off | Off | -- | -- | H | A | -- | -- | H | A | O | -- | |
3rd | Off | On | -- | -- | H | A | A | -- | O | A | O | -- | |
4th | On | On | A | -- | O | A | A | -- | O | A | O | -- | |
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Circuit Description
The 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 when the maximum allowable shift time has been exceeded and 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 for greater than 5 seconds. |
| • | The 1-2 and the 2-3 upshifts are greater than 1.25 seconds. |
| • | The 3-4 upshifts are greater than 6.38 seconds. |
| • | The above conditions exist for 5 consecutive upshifts. |
Action Taken When the DTC Sets
| • | The PCM commands maximum line pressure. |
| • | DTC P1811 is stored in memory. |
Conditions for Clearing the DTC
| • | The PCM turns OFF the MIL after three consecutive ignition cycles 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
| • | 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. |
| • | While driving the vehicle, inspect for loss of power, misfire, or other engine related driveability conditions. |
Test Description
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This step tests for low fluid level, which can cause delayed shifts.
-
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.
-
This step tests for low line pressure, which can cause delayed shifts.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to OBD Powertrain System Check | |||||||
Have you performed the transmission fluid checking procedure? | -- | Go to Transmission Fluid Checking Procedure | ||||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Important: If any other engine or transmission DTCs are set, refer to their respective diagnostic tables first. Does each selected transmission range match the TFP Sw. A/B/C display on the scan tool? Refer to the Range Signal table. | -- | Go to DTC P1810 | ||||||||
4 |
Were any of the shift times above the specified value? | 1-2 or 2-3 upshifts: 1.25 seconds 3-4 upshifts: 6.38 seconds. | Go to Diagnostic Aids. DTC conditions are not present at this time. | |||||||
Perform the line pressure test. Refer to Line Pressure Test. Is the line pressure within specifications? | -- | Go to Symptom Diagnosis table, Low Line Pressure | ||||||||
6 |
Is there excessive contamination in the transmission oil pan? | -- | Go to Unit Repair | |||||||
7 | Inspect the transmission for fluid pressure loss in one of the following areas:
Refer to Unit Repair. Did you find and correct a problem? | -- | -- | |||||||
8 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
