Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSGMC1995SUBURBAN K2500, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 133 (ENGINE CONTROLS - TESTS W/CODES - 4.3L)TROUBLE CODE CHARTSCODE 79, TRANSMISSION FLUID TEMPERATURE HIGH - ALL MODELSDIAGNOSTIC AIDS

1995 GMC Suburban K2500, 6.5 F

Diagnostic Aids

1995 GMC Suburban K2500, 6.5 FSECTION Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 19 other vehicles, including the 1996 Chevrolet Chevy Van, 1995 GMC Vandura Special, 1995 GMC Vandura, 1995 GMC Sonoma, and 1995 GMC Safari. However, it is still accessible from the selected car via links, so may be relevant.

Check harness routing for a potential short to ground in signal circuit. Scan tester displays transmission fluid temperature in degrees Centigrade. After transmission is running, temperature display should rise steadily to about 100°C then stabilize. Test transmission sensor at various temperature levels to determine if sensor is out of calibration. See TRANSMISSION SENSOR - TEMP TO RESISTANCE chart. An out-of-calibration sensor could result in delayed shifts or TCC enabled complaint.

TEMPERATURE-TO-RESISTANCE VALUES ⁽¹⁾⁽²⁾

°F (°C)

Ohms

150 (66)

42-56

100 (38)

159-198

70 (20)

420-514

40 (4)

1308-1609

20 (-7)

3088-3941

0 (-18)

7902-10,943

-40 (-40)

73,556-127,857

⁽¹⁾	Measure resistance across sensor terminals.

⁽²⁾	Temperatures are approximates.

Fig 1: Code 79 Schematic ("C", "K" & "P" Series) Transmission Fluid Temperature High

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.