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.
1993 GMC Yukon AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes - Diesel
- Introduction
- Self-Diagnostic System
- Diagnostic Charts
- Diagnostic System Check (With Automatic Transmission)
- Diagnostic System Check (With Manual Transmission)
- Chart A-1, No Mil (Service Engine Soon) Light (With A/T)
- Chart A-1, No Mil (Service Engine Soon) Light (With M/T)
- A-2, No DLC Data, Mil (Service Engine Soon) Light On At All Times Or Will Not Flash DTC 12 (With A/T)
- A-2, Mil (Service Engine Soon) LT On At All Times Or Will Not Flash DTC 12 (With M/T)
- EPR Solenoid Electrical Check
- EPR Vacuum Circuit Check
- Diagnostic Trouble Code Charts
- DTC 12, No Reference Pulse (With Automatic Transmission)
- DTC 12, No Reference Pulse (With Manual Transmission)
- DTC 14, ECT Sensor - High Temperature Indicated (With A/T)
- DTC 14, ECT Sensor High Temperature Indicated (With M/T)
- DTC 15, ECT Sensor Low Temperature Indicated (With A/ T)
- DTC 15, ECT Sensor Low Temperature Indicated (With M/T)
- DTC 16, Trans. Output Speed Signal Voltage Low (A/T Only)
- DTC 21, Throttle Position Sensor Signal Voltage High (W/ A/T)
- DTC 21, Throttle Position Sensor Signal Voltage High (W/ M/T)
- DTC 22, Throttle Position Sensor Signal Voltage Low (W/ A/T)
- DTC 22, Throttle Position Sensor Signal Voltage Low (W/ M/T)
- DTC 23, Throttle Position Sensor MISADJUSTED
- DTC 24, Vehicle Speed Signal Low ("C" & "K" Series, M/T Only)
- DTC 24, Vehicle Speed Signal Low (With 4L60-E A/T)
- DTC 24, Vehicle Speed Signal Low (With 4L80-E A/T)
- DTC 31, Map Sensor Signal Voltage Low (W/ A/T)
- DTC 31, Map Sensor Signal Voltage Low (W/ M/T)
- DTC 32, EGR Circuit Loop Error ("C" & "K" Series)
- DTC 32, EGR Circuit Loop Error ("G" Series)
- DTC 33, Manifold Absolute Pressure Sensor Signal Voltage High
- DTC 51, Prom Problem
- DTC 52, ECM Fault
- DTC 53, Voltage Reference Overload (W/ A/T)
- DTC 53, Voltage Reference Overload (With Manual Transmission)
- DTC 72, Vehicle Speed Sensor Signal Loss
Factory Service Tools
Use the Manual With the Right Hardware
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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.