What Does P0890 Mean?
The PCM or TCM has detected a lower-than-expected voltage on the transmission control module power relay sense circuit. This circuit monitors the relay that supplies main power to the TCM, and a low reading indicates the relay may not be energizing properly or the sense circuit has a fault to ground. Without reliable power, the TCM cannot properly control transmission operation.
Safety Warning
Loss of TCM power can cause the transmission to default to limp mode, resulting in limited gear availability and unpredictable shift behavior. Avoid highway driving until repaired.
Common Causes
30%
Failed or sticking TCM power relay
25%
Short to ground in the TCM power relay sense circuit wiring
20%
Corroded or loose connector at the TCM power relay or TCM itself
15%
Damaged TCM with internal power supply fault
10%
Blown fuse in the TCM power relay feed circuit
Diagnostic Steps
1
Check all fuses related to the transmission control module power supply and replace any that are blown.
2
Locate the TCM power relay and test it for proper operation by applying battery voltage and ground; listen for the click and verify contact closure with an ohmmeter.
3
With the relay energized, use a multimeter to measure the voltage on the sense circuit wire at the TCM connector; compare to specification (typically battery voltage).
4
Inspect the wiring harness between the TCM power relay and the TCM for chafed insulation, shorts to ground, or corroded terminals.
5
If wiring and relay test good, suspect a faulty TCM; verify by monitoring the sense circuit signal with the TCM disconnected.
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The PCM or TCM has detected a lower-than-expected voltage on the transmission control module power relay sense circuit. This circuit monitors the relay that supplies main power to the TCM, and a low reading indicates the relay may not be energizing properly or the sense circuit has a fault to ground...
The most common cause of P0890 (TCM Power Relay Sense Circuit Low) is: Failed or sticking TCM power relay
Typical repair costs for P0890 range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of TCM power can cause the transmission to default to limp mode, resulting in limited gear availability and unpredictable shift behavior. Avoid highway driving until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0890 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission
Difficulty
Type
Generic (SAE)
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