LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1998 >> Yukon 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Diagnostic Tests >> DTC P0712: Trans. Fluid Temperature (TFT) Sensor Circuit Low Input >> Diagnostic Aids

Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1998 GMC Savana Special, 1998 GMC Savana Camper Special, 1998 GMC Savana, 1998 Chevrolet RV Cutaway, and 1998 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

Inspect wiring for poor connections at VCM and at transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. First diagnose and clear any engine and TP sensor DTCs that are present, then inspect for any transmission DTCs that may have reset. TFT sensor temperature should rise steadily and then stabilize. If DTC P0218 is also set, check transmission cooling system for possible blockage and/or restrictions. Test TFT sensor at various temperatures to evaluate for skewed sensor. See TEMPERATURE-TO-RESISTANCE VALUES  table. A skewed sensor may cause delayed garage shifts or TCC complaints. Check customer driving habits, such as towing in overdrive.

TEMPERATURE-TO-RESISTANCE VALUES (1)

Temperature - °F (°C) Ohms
212 (100) 177
158 (70) 467
95 (35) 1802
50 (10) 5670
-40 (-40) 100707
(1) Measure resistance across sensor terminals.