DTC 59

DTC 59 Transmission Fluid Temperature (TFT) Sensor Circuit High (Low Temperature Indicated):

Transmission Fluid Temperature (TFT) Circuit:

CIRCUIT DESCRIPTION
The Transmission Fluid Temperature (TFT) sensor is a thermistor that controls the signal voltage to the Transmission Control Module (TCM). The TCM supplies a 5 volt reference signal to the sensor on CKT 1227. When the transmission fluid is cold, the sensor resistance is high and the Transmission Control Module (TCM) will sense high signal voltage.
As the transmission fluid temperature warms to normal transmission operating temperature 1OO°C (212°F), the sensor resistance becomes less and the voltage decreases to approximately 1.5 to 2.0 volts.

DTC 59 WILL SET WHEN
^ Signal voltage indicates TFT less than -40°C (-40°F).
^ All conditions are met for 1 second.

ACTION TAKEN (TCM will default to)
The TCM will use a warm default trans fluid temperature value.

DTC 59 WILL CLEAR WHEN
The fault condition(s) no longer exist.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This checks the entire circuit and indicates whether the malfunction is present.
2. This test simulates a DTC 58. If the TCM recognizes the low signal voltage (high temperature), and the scan tool displays 151°C (305°F) or greater, the TCM and wiring are OK.
3. This test checks if CKT 1227 is open. There should be 5 volts present at the sensor connector if measured with J 39200.

DIAGNOSTIC AIDS
Scan tool displays transmission fluid temperature in degrees. After transmission is operating the temperature should rise steadily to about 100°C (212°F) then stabilize.
A faulty connection or an open in CKT 455 or CKT 1227 can result in a DTC 59.
The "Temperature to Resistance Value" scale may be used to check the TFT sensor at various temperature levels to evaluate the possibility of a "skewed" (mis-scaled) sensor. A "skewed" sensor can result in firm shifts, or Torque Converter Clutch (TCC) complaints.