Code P1870

My 98 Transport 3.4 has the SES light on, I had the codes read and I have a P0172 code which I believe is an O2 sensor but now on our way back from Nebraska with the cruise control set at about 70mph the rpm's went sky high, I had to turn off the cruise. This happened a couple of times, now I'm getting a code P1870. Manufacurer Contrl. Transmission. Anyone know what causes this and how to fix it or how much it should cost to have it fixed? I just got this van a month ago. I sure hope I don't have to replace tranny. We only have one vehicle and can't afford that kind of repair. Can somebody please help me?

Most common issue is the tcc valve bore in the valve body, but the code means slippage is detected, a trans shop should do a full scan on the trans for solenoid operation and slippage percentages for a propoer diagnosis.

check this out
http://www.automotivehelper.com/topic213553.htm

Hope this helps.

Document ID# 193083
1998 Pontiac Trans Sport Ext.


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DTC P1870 Transmission Component Slipping
DTC P1870 Thumbnail table Range
Overdrive

Gear
2nd
3rd
4th

1-2 Shift Solenoid
OFF
OFF
ON

2-3 Shift Solenoid
ON
OFF
OFF

4th Clutch
--
--
Applied

2nd Clutch
Applied
Applied
Applied

3rd Clutch
--
Applied
Applied, but not effective

3rd Sprag Clutch
--
Holding
Overrun

1/2 Support Roller Clutch
Holding
Overrun
Overrun

Forward Band
Applied
Applied
Applied

ON = Solenoid Energized
OFF = Solenoid De-energized


Circuit Description
The Powertrain Control Module (PCM) monitors the Torque Converter Clutch (TCC) slip by calculating the difference between the engine speed and the transmission output shaft speed.

When the PCM detects an excessive amount of slip when the TCC is engaged, then DTC P1870 sets. DTC P1870 is a type B DTC.

Conditions for Setting the DTC
No TP DTCs P0122 or P0123.
No VSS DTCs P0502 or P0503.
No TCC enable solenoid electrical DTC P0740.
No 1-2 solenoid performance DTC P0751.
No 1-2 solenoid electrical DTC P0753.
No 2-3 solenoid performance DTC P0756.
No 2-3 solenoid electrical DTC P0758.
No TCC PWM solenoid electrical DTC P1860.
Not in fuel shut off.
The throttle angle is 8-35%.
The transmission is not in first gear.
The transmission gear range is D4.
The transmission fluid temperature is greater than 20°C (68°F).
The engine torque is 70-230 N·m (50-170 lb ft).
The TCC is commanded ON and at maximum apply for more than 5 seconds.
The engine speed is 800-5,000 RPM.
The vehicle speed is 56-132 km/h (35-82 mph).
The speed ratio is 0.7-0.995.
The TCC slip is 200-1,500 RPM for 8 seconds.
The above conditions must occur 3 times with the TCC commanded OFF between each occurrence.

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 inhibits TCC operation.
The PCM inhibits 4th gear, if the transmission is in the hot mode.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the MIL after three consecutive trips 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
Ensure that the vehicle's final drive ratio matches the PCM's calibration.
Ensure that the transmission will shift through all four gears with the gear select lever in the D4 range.
Test Description
The numbers below refer to the step numbers on the diagnostic table.

This step inspects the modulator assembly, which could cause P1870 to set.

These are the components that could cause P1870 to set.



DTC P1870 Transmission Component Slipping Step
Action
Value(s)
Yes
No

1
Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls

2
Have you performed the Transmission Fluid Checking Procedure?
--
Go to Step 3
Go to Transmission Fluid Checking Procedure

3
Install the Scan Tool .
With the engine OFF, turn the ignition switch to the RUN position.
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 stored records from the PCM.


Record the DTC Freeze Frame and Failure Records, then clear the DTC.
Clear the DTC to remove default action and allow TCC operation.
Select TCC Slip Speed.
Drive the vehicle with the gear select lever in D4 range. Ensure the TCC engages.
Is the TCC slip speed greater than the specified value?
200 RPM
Go to Step 4
Go to Diagnostic Aids

4
Inspect the following items:
- The modulator assembly.

- The line pressure. Refer to Line Pressure Check Procedure .

Repair the items if necessary.
Was a condition found and corrected?
--
Go to Step 8
Go to Step 5

5
Inspect the following components for the indicated condition:

• Is the TCC solenoid checkball stuck? Refer to Converter Clutch Apply Rough, Slips, or Shudders .

• Does the TCC apply valve fit poorly? Refer to No Torque Converter Clutch (TCC) Apply .

• Is the converter clutch valve stuck? Refer to Converter Clutch Does Not Release . Refer to No Torque Converter Clutch (TCC) Apply .

• Is the regulator valve stuck? Refer to Converter Clutch Apply Rough, Slips, or Shudders . Refer to No Torque Converter Clutch (TCC) Apply .

• Is the TCC PWM solenoid checkball stuck? Refer to Converter Clutch Does Not Release .

• Is the turbine shaft 0-ring seal cut or missing? Refer to Converter Clutch Apply Rough, Slips, or Shudders . Refer to No Torque Converter Clutch (TCC) Apply .

• Is the torque converter fiber material worn or glazed? Refer to Converter Clutch Apply Rough, Slips, or Shudders .

Was a condition found and corrected?
--
Go to Step 8
Go to Step 6

6
Inspect the following components for the indicated condition:

• Is the 3-4 shift valve stuck? Refer to No 3-4 Shift .

• Are the 4th clutch fiber plates burned or damaged? Refer to No 3-4 Shift .

• Are the 4th clutch piston seals cut or rolled? Refer to No 3-4 Shift .

• Is the driven sprocket support ring rolled or twisted, or is a sleeve worn in the 2nd clutch housing? Refer to First Gear Only . Refer to Harsh or Soft 1-2 Shift Feel . Refer to Shudder 1-2 Shift . Refer to No 2-3 Shift .

• Are the 2nd clutch fiber plates burned or damaged? Refer to First Gear Only . Refer to Shudder 1-2 Shift .

• Are the 2nd clutch piston seals cut or rolled? Refer to First Gear Only . Refer to Shudder 1-2 Shift .

Was a condition found and corrected?
--
Go to Step 8
Go to Step 7

7
Inspect the following components for the indicated condition:

• Are the input shaft seals cut or rolled? Refer to No Drive in Drive Range . Refer to No 2-3 Shift .

• Are the 3rd clutch fiber plates burned or damaged? Refer to No 2-3 Shift .

• Are the 3rd clutch piston seals cut or rolled? Refer to No 2-3 Shift .

• Is the forward band burned or damaged? Refer to No Drive in Drive Range .

• Is the forward band apply piston oil seal cut or rolled? Refer to Delayed Engagement . Refer to Slips in Drive . Refer to No Drive in Drive Range .

Was a condition found and corrected?
--
Go to Step 8
--

8
In order to verify your repair, perform the following procedure:

Using the Scan Tool , clear DTC information.
Operate the vehicle under the following conditions:
- The transmission fluid temperature is greater than 20°C (68°F).

- The throttle position is 8-35%.

- The vehicle is not in fuel shut off.

- The gear range is D4.

- The gear is not 1st.

- The engine torque is 70-230 N·m (50-170 lb ft).

- The PCM commands the TCC ON for more than 5 seconds.

- The TCC slip speed is -20 to +50 RPM for more than 5 seconds.

- The speed ratio is 0.70-0.995.

- The engine speed is 800-1500 RPM.

- The vehicle speed is 56-132 km/h (35-82 mph).

Select Specific DTC. Enter DTC P1870.
Has the test run and passed?
--
System OK
Go to Step 1



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Document ID# 193083
1998 Pontiac Trans Sport Ext.