What Does P0885 Mean?
The TCM has detected an open circuit or general malfunction in the TCM power relay control circuit. The TCM power relay supplies operating voltage to the transmission control module, and if the control circuit is open, the relay cannot be energized. This can prevent the TCM from powering on or maintaining power during operation.
Safety Warning
If the TCM cannot power on, the transmission may be locked in a default gear or completely inoperative. Tow the vehicle to a shop if it will not shift properly.
Common Causes
30%
Open or broken wire in relay control circuit
25%
Failed TCM power relay (open coil)
20%
Corroded or disconnected relay control connector
15%
TCM internal relay driver circuit failure
10%
Blown fuse in relay control circuit
Diagnostic Steps
1
Locate the TCM power relay and test for control voltage at the relay coil pins with key on — one pin should have battery voltage, the other should receive a ground command from the TCM.
2
Measure the relay coil resistance with an ohmmeter — an open reading indicates a failed relay coil.
3
Verify the TCM is commanding the relay by checking for ground at the control pin using a test light or multimeter.
4
Inspect the wiring between the TCM and the relay socket for opens, breaks, or corrosion.
5
If the TCM is not commanding ground, check for power and ground at the TCM itself — it may not have power to drive the relay.
Estimated Repair Cost
$50 - $800
Parts + labor, varies by vehicle and location
The TCM has detected an open circuit or general malfunction in the TCM power relay control circuit. The TCM power relay supplies operating voltage to the transmission control module, and if the control circuit is open, the relay cannot be energized. This can prevent the TCM from powering on or maint...
The most common cause of P0885 (TCM Power Relay Control Circuit /Open) is: Open or broken wire in relay control circuit
Typical repair costs for P0885 range from $50 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
If the TCM cannot power on, the transmission may be locked in a default gear or completely inoperative. Tow the vehicle to a shop if it will not shift properly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0885 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Control Module Power Supply
Difficulty
Type
Generic (SAE)
Recommended Tools
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