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code p1870


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My catera has been experiencing a minor/major problem of late. It seems that as I am driving the exclamation lite! comes on on the dash. According to the manual this indicates a transmission problem. Took it in and had the fluid and trans flushed thinking that was all that was required. As it turns out it still continues to happen. The results , If i stop , say at a light or so, starting off again is reaaaalll slow. I have to stand on the gas to get the car to 25 miles per hour. What I have found is that if I stop , turn the engine off, wait a few minutes, then start again, the light goes off, and the shifting returns to normal.

I took it to the dealer and they said it read code 1870, which according to them means, replace the transmission . at 3000 dollars plus I find this hard to believe in that I stop and restart and temporarily the problem goes away., This all means to me or i suspect a electronic problem and not a gear problem. Any one with any suggestions please let me know. Thanks.


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I dont see any bulletins. I really dont know that much about the German built Catera.

From what I can see....there is a seperate electronic transmission module. This is different then the PCM.

Anyway, here is the code diagnostics....

DTC P1870 TCC Stuck Off

Circuit Description

The TCM can calculate the speed of the turbine in the torque converter by using the Engine Speed, the Output Speed and the Gear. If the TCC solenoid DTC is not set, and the TCM detects a slippage greater than a specific amount with the TCC commanded on, the TCM concludes that the TCC is stuck off (not engaged).

Conditions For Running The DTC

The selector lever position is not equal to P, R, or N.

The transmission is not in default.

The engine speed is greater than 480 RPM.

DTC P0730 is not set.

The TCM commands the TCC on.

Conditions For Setting The DTC

The absolute slippage between the engine speed and the calculated turbine speed is greater than 288 RPM.

Action Taken When the DTC Sets

The TCM illuminates the Service Transmission Lamp (STL) and sends a MIL Request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL.

The ECM records the operating conditions in the Freeze Frame at the time of the MIL Request from the TCM.

The transmission operates in the Default Mode.

Conditions for Clearing the MIL/DTC

The TCM turns off the STL as soon as the fault is no longer present.

The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL Request.

A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic.

The scan tool clears the MIL/DTC.

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