P0882: TCM Power Input Signal Low

What it means

TCM main supply voltage falls below the operating threshold for an extended period, causing reset risk and unreliable shift control.

At a glance

• Usually lights the check-engine light

How it works

The TCM's main supply circuit provides the power the module needs to control transmission shifts. P0882 sets when that supply stays below the module's operating threshold long enough to risk a reset or unreliable shift control.

Common causes

Most likely first.

1. Discharged or weak battery
2. Voltage drop in supply wiring

Symptoms

• Check engine or transmission warning light on
• Harsh, delayed, or missing shifts
• Possible limp mode (locked in one gear)
• Slipping or shuddering during gear changes

How to diagnose it

1. Save freeze-frame data and check battery and TCM voltage readings, noting whether the low supply coincided with starting, idling, or another event.
2. Inspect the battery for a weak charge and check its terminals and the TCM power-feed connections for looseness or corrosion.
3. Measure battery and TCM input voltage during the conditions linked to the fault, and compare results with the manufacturer's specification.
4. Perform a loaded voltage-drop check along the TCM power wiring and ground to locate excessive resistance.
5. If the battery and wiring pass, check the charging system and TCM supply circuit for faults that can pull the input voltage low.

Common fixes

• Clean and tighten battery terminals and TCM power connections.
• Charge or replace a discharged or weak battery.
• Repair high-resistance or damaged TCM power-feed wiring.
• Repair a charging-system fault if it prevents the battery and TCM supply from meeting specification.

Can I keep driving?

If the transmission shifts erratically, avoid driving farther than necessary to reach a safe location or repair. A low supply can reset the TCM and interrupt shift control, potentially leaving the vehicle with limited or no normal shifting.