99 YUKON 4L60e trans limp mode

Electronics are enough to make you cry, sometimes. In your particular transmission, I think you have eight or 10 control modules acting on it. Each control module is a computer. That’s in addition to the ECM (engine control module — the mastercomputer) and the TCM (transmission control module). And, then there are the sensors, like the MAP (Mass Air Pressure) and MAF (Mass Air Flow), in addition to the TPS (Throttle Positioning Sensor) and on and on.

From the sound of it, I think it is more than likely the TCM that has gone bad, although, if your engine is performing poorly, it could be the ECM, though I don’t think that’s the case or you’d be telling me about it, too.

I hate to suggest starting over, but, here’s what I would do. I would go back to square one, insert the OBD-II probe and get a new analysis run. Then, look for any of the following codes that might point where the problem lies. I know there are a lot of numbers, but I think it will help you find the problem, or at least you have a start here and if you need a few dozen more codes I can find them for you. Keep me in the loop. Here’s the list:

4L60E Code (DTC) P0218 Transmission Fluid Over Temperature

4L60E Code (DTC) P0502 Vehicle Speed Sensor (VSS) Circuit Low

4L60E Code (DTC) P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent

4L60E Code (DTC) P0711 TFT Sensor Circuit Range/Performance

4L60E Code (DTC) P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low

4L60E Code (DTC) P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High

4L60E Code (DTC) P0716 Input Speed Sensor Circuit Intermittent

4L60E Code (DTC) P0717 Input Speed Sensor Circuit Low

4L60E Code (DTC) P0719 Brake Switch Circuit Low

4L60E Code (DTC) P0724 Brake Switch Circuit High

4L60E Code (DTC) P0730 Incorrect Gear Ratio

4L60E Code (DTC) P0741 TCC System Stuck Off

4L60E Code (DTC) P0742 TCC System Stuck On

4L60E Code (DTC) P0748 Pressure Control Solenoid Circuit

4L60E Code (DTC) P0751 1-2 Shift Solenoid Valve Performance

4L60E Code (DTC) P0753 1-2 Shift Solenoid Circuit

4L60E Code (DTC) P0756 2-3 Shift Solenoid Valve Performance

4L60E Code (DTC) P0758 2-3 Shift Solenoid Circuit

4L60E Code (DTC) P1520 Gear Indicator System

4L60E Code (DTC) P1521 Transmission Engaged At High Throttle Angle

4L60E Code (DTC) P1522 Park/Neutral To Drive/Reverse At High RPM

4L60E Code (DTC) P1523 Electronic Throttle Control Throttle Return

4L60E Code (DTC) P1527 Transmission Range/Pressure Switch Comparison

4L60E Code (DTC) P1700 Transmission MIL Request

4L60E Code (DTC) P1701 Transmission MIL Request Circuit

4L60E Code (DTC) P1705 P/N Signal Output Circuit

4L60E Code (DTC) P1740 Transmission Torque Reduction Request Circuit

4L60E Code (DTC) P1743 TP Signal From ECM

4L60E Code (DTC) P1760 ECM Supply Voltage Interrupted

4L60E Code (DTC) P1779 Engine Torque Delivered To TCM Signal

4L60E Code (DTC) P1780 Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit

4L60E Code (DTC) P1790 Transmission Control Module Checksum

4L60E Code (DTC) P1791 Transmission Control Module Loop

4L60E Code (DTC) P1792 Transmission Control Module Reprogrammable Memory

4L60E Code (DTC) P1793 Transmission control Module Stack Overrun

4L60E Code (DTC) P1795 CAN Bus-Throttle Body Position

4L60E Code (DTC) P1800 TCM Power Control Relay Circuit Open

4L60E Code (DTC) P1801 Performance Selector Switch Failure

4L60E Code (DTC) P1804 Ground Control Relay

4L60E Code (DTC) P1810 TFP Valve Position Switch Circuit

4L60E Code (DTC) P1811 Maximum Adapt and Long Shift

4L60E Code (DTC) P1812 Transmission Over Temperature Condition

4L60E Code (DTC) P1813 Torque Control

4L60E Code (DTC) P1814 Torque Converter Overstressed

4L60E Code (DTC) P1815 Transmission Range Switch-Start In Wrong Range

4L60E Code (DTC) P1816 TFP Valve Position Switch-Park/Neutral With Drive Ratio

4L60E Code (DTC) P1817 TFP Valve Position Switch-Reverse With Drive Ratio

4L60E Code (DTC) P1818 TFP Valve Position Switch-Drive Without Drive Ratio

4L60E Code (DTC) P1819 Internal Mode Swtich No Start, Wrong Range

4L60E Code (DTC) P1820 Internal Mode Switch Circuit A Low

4L60E Code (DTC) P1822 Internal Mode Switch Circuit B High

4L60E Code (DTC) P1823 Internal Mode Switch Circuit P Low

4L60E Code (DTC) P1825 Internal Mode Switch Illegal Range

4L60E Code (DTC) P1826 Internal Mode Switch Circuit C High

4L60E Code (DTC) P1831 PC Solenoid Power Circuit Low Voltage

4L60E Code (DTC) P1833 A/T Solenoids Power Circuit Low Voltage

4L60E Code (DTC) P1835 Kick-Down Switch

4L60E Code (DTC) P1836 Kick-Down Switch Failed Open

4L60E Code (DTC) P1837 Kick-Down Switch Failed Short

4L60E Code (DTC) P1842 1-2 Shift Solenoid Circuit Low Voltage

4L60E Code (DTC) P1843 1-2 Shift Solenoid Circuit High Voltage

4L60E Code (DTC) P1844 Torque Reduction Signal Circuit Desired By TCM

4L60E Code (DTC) P1845 Transmission Gear Ratio Output Circuit

4L60E Code (DTC) P1847 2-3 Shift Solenoid Circuit High Voltage

4L60E Code (DTC) P1850 Brake Band Apply Solenoid Circuit

4L60E Code (DTC) P1851 Brake Band Apply Solenoid Performance

4L60E Code (DTC) P1852 Brake Band Apply Solenoid Low Voltage

4L60E Code (DTC) P1853 Brake Band Apply Solenoid High Voltage

4L60E Code (DTC) P1860 TCC PWM Solenoid Circuit Electrical

4L60E Code (DTC) P1864 Torque Converter Clutch Circuit

4L60E Code (DTC) P1868 Transmission Fluid Life

4L60E Code (DTC) P1870 Transmission Component Slipping

4L60E Code (DTC) P1871 Undefined Gear Ratio

4L60E Code (DTC) P1873 TCC Stator Temp. Switch Circuit Low

4L60E Code (DTC) P1874 TCC Stator Temp. Switch Circuit High

4L60E Code (DTC) P1875 4WD Low Switch Circuit

4L60E Code (DTC) P1884 TCC Enable/Shift Light Circuit

4L60E Code (DTC) P1886 Shift Timing Solenoid

4L60E Code (DTC) P1887 TCC Release Switch Circuit

4L60E Code (DTC) P1890 ECM Data Input Circuit

4L60E Code (DTC) P1891 Throttle Position Sensor PWM Signal Low

4L60E Code (DTC) P1892 Throttle Position Sensor PWM Signal High

4L60E Code (DTC) P1893 Engine Torque Signal Low Voltage

4L60E Code (DTC) P1894 Engine Torque Signal High Voltage

4L60E Code (DTC) P1895 TCM To ECM Torque Reduction Circuit