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 MANUALSCHEVROLET1994SUBURBAN K2500, 5.7 KREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - ELECTRONIC TRANSMISSIONTROUBLE CODE CHARTSCODE 87, HIGH GEAR RATIO ERRORNOTES
1994 Chevrolet Suburban K2500, 5.7 K
Code 87, High Gear Ratio Error: Notes
1994 Chevrolet Suburban K2500, 5.7 KSECTION Notes
Control module calculates ratio based on the transmission input speed and output speed sensor readings. Control module compares known ratio to the calculated ratio.
- An out-of-calibration transmission range pressure switch could falsely indicate actual transmission range.
- This test verifies the proper ratio.
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.