DTC 58

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The TFT sensor is a thermistor within the TR pressure switch assembly that controls the signal voltage to the PCM. The PCM applies voltage on CKT 1227 to the sensor. When the transmission fluid is cold, the sensor resistance is high and the PCM will sense high signal voltage.

As the transmission fluid temperature warms to the normal transmission operating temperature of 100°C (212°F), the sensor resistance becomes less and the voltage decreases to approximately 1.5 to 2.0 volts. With a DTC 79 also set, check the transmission cooling system.

DTC 58 WILL SET WHEN
^ Signal voltage indicates TFT greater than 151°C (306°F).
^ All conditions met for 1 second.

ACTION TAKEN (PCM WILL DEFAULT TO)
The transmission will use a warm value for operation, but the scan tool will display the actual fluid temperature.

DTC 58 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 test checks for a short to ground or a "skewed" sensor.
2. This test checks for an internal fault within the transmission by creating an open.

DIAGNOSTIC AIDS
Check harness routing for a potential short to ground in CKT 1227.

Scan tool TFT displays should rise steadily to about 100°C (212°F) then stabilize.

Refer to "PCM Intermittent Diagnostic Trouble Codes or Performance." - Intermittent Malfunctions

The temperature to resistance value scale in may be used to test the TFT sensor at the various temperature levels to evaluate the possibility of a "skewed" sensor. A "skewed" (mis-scaled) sensor could result in delayed garage shifts or Torque Converter Clutch (TCC) complaints.