Definition of Code P0828
Code P0828 is a generic powertrain code related to the transmission, including pressure faults and sensor failures. In this case, the Engine Control Module (ECM) detected a fault in the upshift and downshift switch input circuit, reading parameters above the predefined allowable limits.
Codes related to P0828 include:
P0819: Upshift and downshift correlation to transmission range
P0826: Upshift and downshift switch circuit
P0827: Upshift and downshift circuit low
What does Code P0828 mean?
If the ECM detects an anomaly in the voltage or resistance signal in the upshift and downshift switch circuit between the switch and the transmission range correlation unit, a P0828 code will be stored. The circuit includes the switch, all wiring and connectors of the system, as well as the mode actuators. You can locate the upshift and downshift selector near the gear lever in the vehicle’s cabin, which may be mounted on the steering wheel (such as “paddle shifters”). These switches are only used on vehicles with automated manual transmissions.
Vehicles equipped with an OBD-II system use a computerized control system to utilize various inputs to calculate engine driving inputs to determine the necessary gear ratio for optimal fuel efficiency, engine performance, and vehicle longevity.
The ECM initiates upshifts and downshifts through shift solenoids to actuate fluid transfer between hydraulic circuits in each gear set, allowing the driver to choose between multiple shift strategies, such as “Normal” and “Performance” modes. An automated manual transmission enables the driver to quickly shift up or down using a shift lever or button near the gear selector.
What causes Code P0828?
Several issues can cause a P0828 code, including:
- Damaged or faulty upshift and downshift switch
- Damaged, corroded, or poor electrical connection with the upshift and downshift switch
- Open or shorted harness, wiring, or connectors for the upshift and downshift switch
- Spilled fluids on the gear lever in the vehicle’s cabin
- Damaged or faulty ECM (rare)
What are the symptoms of Code P0828?
Symptoms of a P0828 code may include:
- Check engine or warning light may illuminate
- There may be no symptoms for this diagnostic trouble code (DTC)
- Manual shift function may be disabled
- The vehicle may enter “limp mode” – meaning the transmission may shift more roughly and the torque converter lockup mode may be eliminated
- The overdrive light may flash
How does a mechanic diagnose Code P0828?
A mechanic can use several methods to diagnose a P0828 fault code, including:
Using an OBD-II scanner to check for a stored P0828 fault code
- Visually inspect the cabin for any spills that may have entered the upshift and downshift switch
- Visually inspect the wiring circuits for signs of damage, corrosion, or wear
- Check the reference voltage and ground signals at the upshift and downshift switch and actuators
- Use a digital volt/ohmmeter to check continuity and resistance if the reference voltage and/or ground signals were open
- Test all associated circuits and switches for continuity and resistance
Common mistakes when diagnosing Code P0828
Before checking and diagnosing faulty transmission wiring, ensure to check if any fluid has been spilled on the gear lever in the cabin. Clean and repair any damaged wiring or connectors at the shift switch location and retest the system before performing more complicated repairs.
How severe is Code P0828?
Since the safe operation of a vehicle can be affected due to faults that store a P0828 code, this code is considered potentially serious. When this code appears, it is recommended to bring your vehicle to your local service center or a mechanic immediately for repair and diagnosis.
What repairs can fix Code P0828?
Several repairs can correct a P0828 fault code and include:
- Clean the gear lever area of any spilled fluids
- Repair or replace any damaged or shorted electrical wiring, harness, or connectors
- Repair or replace the damaged or faulty shift switch
- Clear all codes, test the vehicle, and rescan to see if any codes reappear
Additional considerations regarding Code P0828
It is recommended to first check the switch location inside the cabin for spilled fluids, clean, repair any damaged wiring if necessary, and retest before moving on to other aspects of the switch circuit.