P0888 critical

TCM Power Relay Sense Circuit

The P0888 code means the vehicle's onboard diagnostic system has detected: TCM Power Relay Sense Circuit. This is a critical severity code.

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Keep driving?: No -- stop driving
DIY difficulty: hard
Estimated cost: $100 - $1,500 (parts and labor)

Check Your Fluid First

ANCEL AD310 OBD-II Scanner

Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.

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Read Transmission Codes

LAUNCH CRP123X (Reads All Systems)

Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.

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Common Symptoms

Check Engine Light on
TCM cannot verify relay status
Transmission in limp mode
Erratic transmission behavior

Probable Causes (Ranked by Likelihood)

TCM power relay sense circuit fault Very High
Corroded or damaged wiring connections High
Low battery voltage affecting TCM operation Moderate
TCM internal circuit failure Low

Step-by-Step Diagnostic Procedure

Use a scan tool to read TCM Power Relay Sense data
Check TCM power supply and ground connections for proper voltage and continuity
Inspect TCM relay and related fuses
Verify battery and charging system health with a multimeter

Frequently Asked Questions

What does P0888 indicate?

P0888 indicates a problem with the tcm power relay sense circuit. This is a critical issue that can prevent the transmission from operating correctly.

Can a weak battery cause this code?

Yes. TCM modules are sensitive to voltage supply quality. A weak battery, poor connections, or charging system issues can cause various TCM power-related codes. Always test the battery and charging system first.

Do I need a TCM replacement?

Not necessarily. Most TCM codes are caused by external issues like power supply problems, relay failures, or wiring faults. A TCM replacement is typically only needed when all external causes have been ruled out.