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Home >> GMC >> 1995 >> Forward Control 4.3 Z, Standard >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> Automatic Transmission Diagnosis - 4L80-E >> Diagnostic Charts - Diesel >> DTC 59, Trans. Fluid Temp. Sensor Circuit High (Low Temperature Indicated) >> Diagnostic Aids

Diagnostic Aids

Scan tester displays transmission fluid temperature in degrees. After transmission is operating, temperature should rise steadily to about 212°F (100°C) then stabilize. A faulty connection or open in sensor ground circuit or 5-volt TFT signal circuit may cause DTC 59 to set.

Test transmission fluid temperature sensor at various temperature levels to evaluate possibility of a skewed (out-of-range) sensor. See TEMPERATURE VS. RESISTANCE VALUES table. A skewed sensor could result in firm shifts or TCC complaints.

TEMPERATURE VS. RESISTANCE VALUES

Temperature °F (°C) (1)(2) Ohms
-40 (-40) 100,700
-22 (-30) 52,700
-4 (-20) 28,680
5 (-15) 21,450
14 (-10) 16,180
23 (-5) 12,300
32 (0) 9,420
41 (5) 7,280
50 (10) 5,670
59 (15) 4,450
68 (20) 3,520
77 (25) 2,796
86 (30) 2,238
95 (35) 1,802
104 (40) 1,459
113 (45) 1,188
122 (50) 973
140 (60) 667
158 (70) 467
176 (80) 332
194 (90) 241
212 (100) 177
(1) Measure resistance across sensor terminals.
(2) Temperatures are approximate.