OBD Code P0973: Shift Solenoid A Control Circuit Low

Q: What does OBD code P0973 mean?

Shift Solenoid A Control Circuit Low. The transmission control computer detects that Shift Solenoid A isn't receiving enough electrical power to operate properly. Think of it like a doorbell that's too quiet to ring the bell—the solenoid needs a strong signal to switch gears.

Q: What are the symptoms of fault code P0973?

Transmission stuck in limp mode or default gear, Check Engine Light illuminated, Harsh or delayed gear shifts

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What This Actually Means

In plain language — no jargon

The transmission control computer detects that Shift Solenoid A isn't receiving enough electrical power to operate properly. Think of it like a doorbell that's too quiet to ring the bell—the solenoid needs a strong signal to switch gears.

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Symptoms You May Notice

3 known symptoms for this code

Transmission stuck in limp mode or default gear

Check Engine Light illuminated

Harsh or delayed gear shifts

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Embedded Systems Insight

What the ECU/ECM is actually computing

The ECM monitors the voltage and current flowing through Shift Solenoid A's control circuit. It expects a specific voltage range when commanding the solenoid to operate. If voltage drops below threshold or current draw is insufficient, the ECU triggers this fault.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
Control Circuit Voltage	11-14 volts	Below 10 volts or open circuit
Solenoid Current Draw	0.5-2.0 amps	Below 0.3 amps or no current detected

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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

Wiring harness connector

Inspect and clean the solenoid connector terminals for corrosion or loose connections.

2

Shift Solenoid A

Replace the solenoid if resistance testing shows out-of-spec coil resistance (typically 4-8 ohms).

3

Transmission control module wiring

Repair any broken or damaged wires in the circuit between the ECM and solenoid.