P273D
Gear Shift Control Module A Supply Voltage High
The gear shift control module A reports a supply voltage above the operating range.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
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
Common causes
Ordered by how often each turns out to be the cause.
- Alternator regulator failed to limit outputCommon
- Load dump transient after disconnecting a heavy loadLess likely
Parts involved
- Gear Shift Module A
- Charging System
P273D is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.