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The famous P1870 code/slipping in fourth


grave digger
02-01-2008, 04:34 PM
I have a 98' Grand Am GT 2.4. I was wondering if a faulty speed sensor could fool the ECM into thinking the transmission is slipping. The code sets when driving above 55 mph for a few minutes. The transmission shifts as it should and the torque converter is locking in fourth as it should and the fluid is not burnt. I have taken down the tranny pan and their is no metal shavings nor is their any abnormal deposits.:screwy: Any help on this matter is much appreciated.

xeroinfinity
02-01-2008, 10:09 PM
A bad speed sensor might effect the ETC.

A harsh 1-2 shift or DTC P1870 may be difficult to duplicate when the transmission temperature is below 200°.

The problem might be due to wear in the control valve body. The wear occurs in the bore that contains the TCC isolator and regulator valves, and results in poor, or no, TCC apply.
And this isnt hard to change nor real expensive.

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