The internal mode switch (also known as the transmission range selector or park/neutral switch) uses electrical voltage signals to inform the transmission control unit of the gear range you selected with the shifter. If these signals are off, the TCM might command maximum line pressure, which can significantly damage internal components.
How Serious is the Code?
The P1824 DTC is fairly serious, because the increased line pressure can significantly damage the clutches, seals and other vital components.
Symptoms of a P1824 include:
- Extremely hard gear changes
- Transmission won’t engage the correct gear
- PRNDL display stops working
- Limited torque converter operation
- Limp Mode
- Internal mode switch failure
- Shift cable damage or it’s out of adjustment
How to Diagnose the Code?
The first thing the technician should inspect trying to diagnose a P1823 diagnostic trouble code is the shift linkage. If it is not out of adjustment, then the problem may will be the internal mode switch.
What Repairs Will Fix P1824?
- Adjusting the shift cable
- Replacing the internal mode switch
P1819 – Internal Mode Switch – No Start\Wrong Range
P1820 – Internal Mode Switch Circuit A Low
P1821 – Internal Mode Switch Circuit B Low
P1822 – Internal Mode Switch Circuit B High
P1825 – Internal Mode Switch Invalid Range
P1826 – Internal Mode Switch Circuit C High