Code 59, Trans. Temperature Sensor Low Temperature - 3.4L "F" Body, 4.3L & 5.7L "B", "D", "F" & "Y" Bodies: Notes

Fig 1: Code 59 - Trans. Temp. Switch Schematic (3.4L "F" Body)

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Fig 2: Code 59 - Trans. Temp. Switch Schematic (4.3L & 5.7L "B" Body)

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Fig 3: Code 59 - Trans. Temp. Switch Schematic (5.7L "D" Body)

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Fig 4: Code 59 - Trans. Temp. Switch Schematic (5.7L "F" Body)

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Fig 5: Code 59 - Trans. Temp. Switch Schematic (5.7L "Y" Body)

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PCM supplies and monitors a 5-volt reference to sensor. As transmission temperature changes, sensor resistance changes, affecting monitored voltage. When fluid is cold, resistance is high, resulting in a high monitored voltage. When fluid is hot, resistance is low, resulting in a low monitored voltage.

1. Checks for an out-of-calibration sensor.
2. Simulates a Code 58. If PCM recognizes low signal voltage, and scan displays 146 degrees centigrade or higher, PCM and wiring are okay.
3. Checks if signal circuit is open. Five volts should be present at sensor connector.