DTC code 59

[6.542762mw]

Is it possible that after installing the 97 cooling mod that Im running too cool?

Im always checking for DTC codes and after the cooling up grade I found code 59, trans temp too cool! could it be true? Amazing! Any and all thoughts? tongue.gif


Mark

[DmaxMaverick]

Doubtful. It is possible for the engine to run too cool to be efficient, but not the tranny under most conditions. Something else is wrong. Perhaps a sensor, or you have a restriction in the tranny the ECM sees as excessively high ATF viscocity. When you get the code, feel the tranny pan with your hand. If it feels hot, it is.

The tranny will warm up regardless of engine temp. An exception would be extreme cold (-20

[moondoggie]

Good Day!

For my 95's, DTC 59 reads, "Trans Fluid Temp Circuit High." My 95's have a temperature sensor in the tranny (4L80E).

If memory serves, this DTC is NOT the same as high temperature, but the PCM is seeing a signal input much higher than it expects to see. This would relate to a wiring issue, or maybe a bad temp. sensor, if your 93 has one.

The only temperature-related tranny code I could find at a quick glance was DTC 79, which reads, "Trans Fluid Overtemp," but this code is only listed for the 4L60E, NOT the 4L80E. Hmmm...

Good Luck & Blessings!

[6.542762mw]

Havent really had it going long enough to figure out when its happening. I have noticed that I have erratic shifting. Mainly this happens after 45 mph and it feels like it locks and unlocks quickly. Is there away to test that trans temp sender with out removing the pan and replacing it? I will clear the codes and check to see what happens.

Thanks

Mark

[JohnC]

Originally posted by 6.542762mw:
Is there away to test that trans temp sender with out removing the pan and replacing it? A scanner will tell you what the sensor is indicating. Your symptoms would indicate that the PCM thinks the temp is too hot, or cannot determine the temp and assumes too hot. A "circuit high" indication usualy means a bad connection or broken wire.