The powertrain control module (PCM) monitors the engine speed, and the
transmission output shaft speed. The PCM calculates turbine shaft speed
and torque converter clutch (TCC) slip speed by using inputs from the automatic
transmission input shaft speed sensor (AT ISS), automatic transmission
output shaft speed sensor (AT OSS), and other transmission components.
The forward clutch housing is used as the AT ISS rotor. Whenever the TCC
is engaged, engine speed and turbine speed will closely match, indicating
low TCC slip speed. In D3 with the TCC engaged, calculated transmission
component slip can only occur in the torque converter. In D4 OVERDRIVE with
the TCC engaged, transmission component slip can occur in the TCC or the
fourth clutch assembly.
If the PCM detects an excessive TCC slip speed in D4 OVERDRIVE, when
the TCC should be engaged, then DTC P0894 sets. DTC P0894
is a type C DTC. For California emissions vehicles, DTC P0894
is a type B DTC.
The PCM detects slip in the torque converter clutch and/or the fourth
gear clutch pack with the TCC in an apply or locked mode. DTC P1870
sets during the second consecutive trip when one of the following condition
occurs:
The numbers below refer to the step numbers on the diagnostic table.
Step
| Action
| Value(s)
| Yes
| No
|
1
| Did you perform the
Diagnostic System Check - Engine Controls?
| --
| Go to
Step
2
| Go to
Diagnostic System Check - Engine Controls
in Engine Controls
- 6.0L or
Diagnostic System Check - Engine Controls
in Engine Controls - 8.1L
|
2
| Perform the Transmission Fluid Checking Procedure.
Refer to
Transmission Fluid Check
.
Was the Transmission Fluid Checking Procedure performed?
| --
| Go to
Step 3
| Go to
Transmission Fluid Check
|
3
|
- Install a scan tool.
- Turn ON the ignition, with the engine OFF.
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.
- Record the Freeze Frame and Failure Records.
- Clear the DTCs.
- With the engine idling and at normal operating temperature, apply
the brake pedal.
- Select each transmission range: D1, D2, D3, D4, N, R, and P.
Refer to
Transmission Fluid Pressure Manual Valve Position Switch Logic
.
Does each selected transmission range match the scan tool TFP switch
A/B/C display?
| --
| Go to
Step 4
| Go to
DTC P1810
|
4
| Drive the vehicle under the following conditions:
• | The TFT is 20-130°C (50-266°F). |
• | The transmission is in D4. |
• | The TCC duty cycle is greater than 80 percent. |
• | The TP angle is 10-80 percent. |
At any time is the TCC slip speed greater than the specified value
for 10 seconds?
| 120 RPM
| Go to
Step 5
| Go to Diagnostic Aids
|
5
| Drive the vehicle under the following conditions:
• | The transmission is in D3. |
• | Command the TCC ON with the scan tool. |
• | The TP angle is 10-80 percent. |
At any time is the TCC slip speed greater than the specified value
for 10 seconds?
| 120 RPM
| Go to
Step 7
| Go to
Step 6
|
6
| Repeat the procedure in Step 4. Drive the vehicle under the following conditions:
• | The transmission is in D4. |
• | The TCC duty cycle is greater than 80 percent. |
• | The TP angle is 10-80 percent. |
Is the TCC slip speed greater than the specified value?
| 120 RPM
| Go to
Step 8
| Go to Diagnostic Aids
|
7
|
- Connect the J 21867
pressure gauge to the transmission line pressure tap.
- Perform the Line Pressure Check Procedure.
Refer to
Line Pressure Check
.
Is the line pressure within specifications?
| --
| Go to
Step 8
| Go to
Symptoms - Automatic Transmission
|
8
|
- Inspect the transmission for the following conditions:
• | TCC enable valve mechanically stuck OFF |
• | TCC solenoid valve O-ring seals worn |
• | TCC shift valve stuck in the released position |
• | Turbine shaft oil holes plugged |
• | Turbine shaft seals leaking |
• | Converter limit valve plug leaking |
• | TCC PWM solenoid valve mechanically stuck OFF |
• | TCC regulator apply valve stuck in the released position |
- Repair the condition as necessary.
Did you complete the repair?
| --
| Go to
Step 10
| Go to
Step 9
|
9
|
- Inspect the transmission for the following conditions:
• | Fourth clutch plates damaged or burned |
• | Fourth clutch piston seals leaking |
• | Fourth clutch cup plug leaking |
• | Fourth clutch retainer ring not seated |
• | Overrun clutch plates damaged or burned |
• | Overdrive clutch roller assembly not holding |
- Repair the condition as necessary.
Did you complete the repair?
| --
| Go to
Step 10
| --
|
10
| Perform the following procedure in order to verify the repair:
- Select DTC.
- Select Clear Info.
- Operate the vehicle under the following conditions:
• | Ensure that TFT is 20-130°C (50-266°F). |
• | Drive the vehicle in 4th gear, with the TCC commanded ON. |
• | The TP angle is 10-100 percent. |
• | TCC slip speed must be -25 to +25 RPM for 10 seconds. |
- Select Specific DTC.
- Enter DTC P0894.
Has the test run and passed?
| --
| Go to
Step
11
| Go to
Step
2
|
11
| With the scan tool, observe the stored information, capture info and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?
| --
| Go to
Diagnostic Trouble Code (DTC) List
in Engine Controls - 6.0L or
Diagnostic Trouble Code (DTC) List
in Engine Controls - 8.1L
| System OK
|