DTC P1870 Transmission Component
Slipping 3.8L
The powertrain
control module (PCM) monitors the difference between engine speed and
transmission output speed. In D3 drive range with the TCC engaged, the engine
speed should closely match the transmission output speed. In D4 drive range,
with the TCC engaged, the TCC slip speed should be -20 to +40 RPM.
When the PCM detects
excessive TCC slip when the TCC should be engaged, then DTC P1870 sets.
DTC P1870 is a type B DTC.
Conditions
for Running the DTC
- No TP sensor DTCs P0122 or P0123.
- No VSS assembly DTCs P0502 or P0503.
- No TCC solenoid valve DTC P0740.
- No 1-2 SS valve DTC P0753.
- No 2-3 SS valve DTC P0758.
- No 3-2 SS valve assembly
DTC P0785.
- No TCC PWM solenoid valve
DTC P1860.
- The engine speed is greater than
450 RPM for 5 seconds.
- The engine is not in fuel cutoff.
- The TP angle is 8-35%.
- The engine torque is
40-450 lbs ft.
- The vehicle speed is
48-131 km/h (30-82 mph).
- The speed ratio is 0.65-0.98 (speed
ratio is engine speed divided by transmission output speed).
- The engine speed is
1000-3000 RPM.
- The gear range is D4.
- The commanded gear is not 1st gear
- The TFT is between 20-130°C
(68-266°F).
- The shift solenoid performance
diagnostic counters are zero.
- The TCC is commanded ON for
5 seconds.
Conditions
for Setting the DTC
DTC P1870 sets if
the following conditions occur for three TCC cycles.
- The TCC is at maximum duty cycle for
5 seconds.
- The TCC slip speed is
200-800 RPM for 7 seconds.
- Important
The
following actions may occur before the DTC sets.
If
4th gear is commanded, the TCC is commanded ON and at maximum duty cycle for
5 seconds, the TP angle is 7-40%, and the transmission slip counter has
incremented to either 1 or 2 (out of 3 to increment the fail counter for the
current ignition cycle), then the following slip conditions and actions may
increment the fail counter for the current ignition cycle: These conditions must
occur sequentially.
- Condition 1: If the TCC slip speed is
200-800 RPM for 7 seconds, then the PCM commands maximum line
pressure and freezes shift adapts from being updated.
- Condition 2: If Condition 1 is met and the TCC
slip speed is 200-800 RPM for 10 seconds, then the PCM commands
the TCC OFF for 1.5 seconds.
- Condition 3: If Condition 2 is met and the TCC
slip speed is 200-800 RPM for 15 seconds, then the fail counter
on the current ignition cycle is incremented. The above slip conditions
and actions may be disregarded if the TCC is commanded OFF at any time as
a result of a driving maneuver (sudden acceleration or deceleration).
Action
Taken When the DTC Sets
- The PCM illuminates the malfunction
indicator lamp (MIL) during the second consecutive trip in which the
Conditions for Setting the DTC are met.
- The PCM commands maximum line
pressure.
- The PCM inhibits TCC engagement.
- The PCM inhibits 4th gear if the
transmission is in hot mode.
- The PCM freezes shift adapts from
being updated.
- The PCM records the operating
conditions when the Conditions for Setting the DTC are met. The PCM stores
this information as Freeze Frame and Failure Records.
- The PCM stores DTC P1870 in PCM
history during the second consecutive trip in which the Conditions for
Setting the DTC are met.
Conditions
for Clearing the MIL/DTC
- The PCM 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 PCM clears the DTC from PCM
history if the vehicle completes 40 warm-up cycles without an
emission-related diagnostic fault occurring.
- The PCM 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 PCM.
- Bronze material found in the
transmission oil pan may indicate stator shaft bushing wear. If bushing
wear is suspected, inspect the stator shaft and the input (turbine) shaft
for damage.
- Refer to Symptom
Diagnosis for more information.
The numbers below refer
to the step numbers on the diagnostic table.
|
DTC P1870 Transmission Component Slipping (3.8L) Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain Diagnostic System Check?
|
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Go to A
Powertrain On Board Diagnostic (OBD) System Check
in Engine Controls |
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|
Inspect
for correct transmission fluid level. Refer to Transmission
Fluid Checking Procedure . Did you perform the fluid checking procedure? |
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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.
Important It
may be necessary to allow multiple TCC cycles to occur in order to verify a
slipping condition. It may also be necessary to ensure the transmission is
warm before performing this step.
Does
the Scan Tool
TCC Slip Speed measure within the specified range for 7 seconds? |
200-800 RPM |
Go to Diagnostic Aids |
||
Did
you find and correct the condition? |
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Did
you find and correct the condition? |
-- |
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Did
you find and correct the condition? |
-- |
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|
Inspect
the torque converter assembly for the following conditions:
Did
you find and correct the condition? |
-- |
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|
Inspect
the oil pump assembly for the following conditions:
Refer
to Transmission
Overhaul Procedure in the 4L60-E Section of the Transmission Unit Repair
Manual. Did you find and correct the condition? |
-- |
|||
|
Inspect
the input housing and shaft assembly for the following conditions:
Refer
to Transmission
Overhaul Procedure in the 4L60-E Section of the Transmission Unit Repair
Manual. Did you find and correct the condition? |
-- |
|||
|
Inspect
the 2-4 band assembly for the following conditions:
Refer
to Transmission
Overhaul Procedure in the 4L60-E Section of the Transmission Unit Repair
Manual. Did you find and correct the condition? |
-- |
|||
|
Inspect
the forward clutch assembly for the following conditions:
Refer
to Transmission
Overhaul Procedure in the 4L60-E Section of the Transmission Unit Repair
Manual. Did you find and correct the condition? |
-- |
|||
|
Inspect
the 3-4 clutch assembly for the following conditions:
Refer
to Transmission
Overhaul Procedure in the 4L60-E Section of the Transmission Unit Repair
Manual. Did you find and correct the condition? |
-- |
Go to Diagnostic Aids |
||
Important The
Clear TAPS function will clear all adapt cells. This may affect transmission
performance. The PCM will update the transmission adapt cell values as the
vehicle is driven.
Did
you complete the above procedure? |
-- |
-- |
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|
Perform
the following procedure in order to verify the repair:
Has
the test run and passed? |
-- |
System OK |