DTC P1870 Transmission Component Slipping Gas
Circuit Description
The vehicle control module (VCM) monitors the engine speed, and the transmission output shaft speed. The VCM calculates turbine shaft speed and torque converter clutch (TCC) slip speed by using inputs from the transmission input (shaft) speed sensor (ISS), transmission output (shaft) speed sensor (OSS), and other transmission components. The forward clutch housing is used as the 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 VCM detects an excessive TCC slip speed in D4 OVERDRIVE, when the TCC should be engaged, then DTC P1870 sets. DTC P1870 is a type C DTC. For California emissions vehicles, DTC P1870 is a type B DTC.
Conditions for Running the DTC
The following conditions occur 3 times for 10 seconds:
| • | No MAP sensor DTCs P0101, P0102 or P0103. |
| • | No MAF sensor DTCs P0106, P0107 or P0108. |
| • | No engine speed DTCs P0335, P0336, P0337, or P0338. |
| • | No TP sensor DTCs P0121, P0122, or P0123. |
| • | No OSS DTC P0502. |
| • | No ISS DTCs P0716 or P0717. |
| • | No TCC PWM solenoid valve DTCs P0741, P0742 or P1860. |
| • | No 1-2 SS valve DTCs P0751 or P0753. |
| • | No 2-3 SS valve DTCs P0756 or P0758. |
| • | No TFP manual valve position switch DTCs P1810. |
| • | The engine speed is greater than 475 RPM for 7 seconds, and not in fuel cutoff mode. |
| • | The TP sensor is 7-80%. |
| • | Engine speed is 1250-5500 RPM . |
| • | The engine vacuum is 0-105 kPa. |
| • | The TFT is 20-130°C (68-266°F). |
| • | Vehicle speed is 56.3-177 km/h (35-110 MPH) |
| • | TFP manual valve position switch indicates D4. |
| • | The vehicle speed is above 56 km/h (35 mph). |
| • | Speed ratio is 1.30-0.70 for 7.4L. |
| • | The engine torque is: |
| - | 95-542 N·m (70-400 lb ft) |
| - | 108-403 N·m (80-500 lb ft) |
| • | The TCC is commanded ON for 5 seconds or more. |
| • | TCC duty cycle is greater than 99%. |
Conditions for Setting the DTC
| • | All conditions for running the DTC are met for 10 seconds for 3 occurrences. |
| • | The VCM detects a slip speed of: |
| - | 120-550 RPM (5.7L) |
| - | 110-550 RPM (7.4L) |
Action Taken When the MIL/DTC Sets
| • | The VCM illuminates the malfunction indicator lamp (MIL) for California emissions vehicles. |
| • | The VCM commands maximum line capacity. |
| • | The VCM inhibits the TCC engagement. |
| • | The VCM inhibits 4th gear if in hot mode. |
| • | The VCM freezes shift adapts. |
| • | The VCM stores DTC 1870 in VCM History. |
Conditions for Clearing the MIL/DTC
| • | For California emissions, the VCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool clears the DTC from VCM history. |
| • | For California emissions, the VCM clears the DTC from VCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring. |
| • | For Federal emissions, the VCM clears the DTC from VCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the VCM. |
Diagnostic Aids
| • | A TFP manual valve position switch malfunction can set DTC P1870. |
| • | A mechanical failure of the shift solenoids or TCC PWM solenoid valve can set DTC P1870. |
| • | Internal transmission failures can result in a DTC P1870. |
| • | Sticking or contaminated shift valves may cause intermittent slipping in D4. |
| • | First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch can set a DTC P1870.
-
This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in fourth gear; and confirms that the fault is present.
-
This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in third gear.
-
This step tests for a sticking TCC shift valve.
-
This step tests for proper transmission line pressure.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain Diagnostic System Check? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check 5.0/5.7L or Powertrain On Board Diagnostic (OBD) System Check 7.4L | |||||||||
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Was the Transmission Fluid Checking Procedure performed? | -- | Go to Transmission Fluid Check | |||||||||
Important: Before clearing the DTC, 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 VCM. Refer to the Transmission Fluid Pressure Manual Valve Position Switch Logic table. Does each selected transmission range match the scan tool TFP switch A/B/C display? | -- | |||||||||||
Drive the vehicle under the following conditions:
At any time is the TCC slip speed greater than the specified value for 10 seconds? | 120 RPM (5.7L) 110 RPM (7.4L) | Go to Diagnostic Aids | ||||||||||
Drive the vehicle under the following conditions:
At any time is the TCC slip speed greater than the specified value for 10 seconds? | 120 RPM (5.7L) 110 RPM (7.4L) | |||||||||||
Repeat the procedure in step 4. Drive the vehicle under the following conditions:
Is the TCC slip speed greater than the specified value? | 120 RPM (5.7L) 110 RPM (7.4L) | |||||||||||
7 | Refer to Symptom Diagnosis Slipping TCC. Was the condition corrected? | -- | -- | |||||||||
Refer to Line Pressure Check . Is the line pressure within specifications? | -- | Go to Symptom Diagnosis Low Line Pressure | ||||||||||
9 |
Refer to Automatic Transmission Fluid and Filter Replacement . Is the fluid or the pan contaminated? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||
10 |
Was the condition found? | -- | ||||||||||
11 | Inspect the following components for contamination or sticking.
Was the condition found? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||
12 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
DTC P1870 Transmission Component Slipping Diesel
Circuit Description
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 transmission input shaft speed (ISS) sensor, transmission output shaft speed (OSS) sensor, and other transmission components. The forward clutch housing is used as the ISS sensor 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 P1870 sets. DTC P1870 is a type C DTC.
Conditions for Running the DTC
| • | No MAP DTCs P0106, P0107 or P0108. |
| • | No engine speed DTC P0335. |
| • | No A/T ISS sensor DTCs P0716 or P0717. |
| • | No OSS sensor DTCs P0502 or P0503. |
| • | No TCC PWM solenoid valve DTCs P0741, P0742, or P1860. |
| • | No 1-2 SS valve DTCs P0751, P0752, P1842 or P1843. |
| • | No 2-3 SS valve DTCs P0756, P0757, P1845 or P1847. |
| • | The TCC is applied longer than 5.0 seconds. |
| • | The TCC duty cycle is greater than 75%. |
| • | The engine is running more than 475 RPM for greater than 7 seconds. |
| • | No TFP manual valve position switch DTCs P1810, P1842, P1843, P1845 or P1847. |
| • | The gear range is D4. |
| • | The APP angle is 12-80%. |
| • | The TFT is 20-130°C (68-266°F). |
| • | The engine speed is 1200-3750 RPM. |
| • | System voltage is 8.0-18.0 volts. |
| • | The vehicle speed is greater than 48 km/h (30 mph). |
| • | The engine torque is 95-644 N·m (70-265 lb ft). |
Conditions for Setting the DTC
The above conditions for running the DTC are met, with 4th gear commanded, and the TCC ON, and one of the following conditions occur:
Condition 1 (after 3 occurrences)
The PCM detects a slip speed of 120-525 RPM for greater than 6.0 seconds.
Condition 2 (in the following sequence for one occurrence)
- The PCM detects a TCC slip speed of 110-500 RPM for 10 seconds.
- The PCM detects a TCC slip speed of 110-500 RPM for 10 seconds.
- The PCM detects a TCC slip speed of 110-500 RPM for 10 seconds.
| • | The PCM commands maximum line pressure. |
| • | The PCM freezes shift adapts. |
The PCM commands the TCC OFF for 1.5 seconds.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | The PCM commands maximum line pressure. |
| • | The PCM inhibits the TCC engagement. |
| • | The PCM inhibits 4th gear if in hot mode. |
| • | The PCM freezes shift adapts. |
| • | The PCM stores DTC P1870 in PCM History. |
Conditions for Clearing the MIL/DTC
| • | For Federal and California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool clears the DTC from PCM history. |
| • | For Federal and California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring. |
| • | For vehicles equal to or greater than 15,000 lbs GVW, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | A TFP manual valve position switch malfunction can set DTC P1870. |
| • | A mechanical failure of the shift solenoids or TCC PWM solenoid valve can set DTC P1870. |
| • | Internal transmission failures can result in a DTC P1870. |
| • | Sticking shift valves or contamination may cause intermittent slipping in D4. |
| • | First, diagnose and clear any engine DTCs that are present. Then inspect for any transmission DTCs that may have reset. |
| • | DTC P1860 can cause a DTC P1870 to set. Diagnose the electrical codes first. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch can set a DTC P1870.
-
This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in fourth gear; and confirms that the fault is present.
-
This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in third gear.
-
This step tests for a sticking TCC shift valve.
-
This step tests for proper transmission line pressure.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain Diagnostic System Check? | -- | ||||||||||
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Was the procedure performed? | -- | Go to Transmission Fluid Check | |||||||||
Important: Before clearing the DTC, 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. Refer to the Transmission Fluid Pressure Manual Valve Position Switch Logic table. Does each selected transmission range match the scan tool TFP Switch A/B/C display? | -- | |||||||||||
Drive the vehicle under the following conditions:
At any time is the TCC slip speed greater than the specified value for 6 seconds? | 120 RPM | Go to Diagnostic Aids | ||||||||||
Drive the vehicle under the following conditions:
At any time is the TCC slip speed greater than the specified value for 6 seconds? | 110 RPM | |||||||||||
Repeat the procedure in step 4. Drive the vehicle under the following conditions:
Is the TCC slip speed greater than the specified value? | 120 RPM | |||||||||||
7 | Refer to Symptom Diagnosis Slipping TCC. Was the condition corrected? | -- | -- | |||||||||
Refer to Line Pressure Check . Is the line pressure within specifications? | -- | Go to Symptom Diagnosis Low Line Pressure | ||||||||||
9 |
Refer to Automatic Transmission Fluid and Filter Replacement . Is the fluid or the pan contaminated? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||
10 |
Was the condition found? | -- | ||||||||||
11 | Inspect the following components for contamination or sticking.
Was the condition found? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||
12 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
