Code
P0773
HUMMER
P — Powertrain
Shift Solenoid E Electrical
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in shift solenoid E circuit
- Poor, corroded, or disconnected connector at the solenoid or harness
- Faulty shift solenoid E (internal coil or valve sticking)
- Blown fuse or faulty transmission relay affecting solenoid supply
- Low battery/poor charging system voltage under load
- Damaged transmission internal harness (chafing at bellhousing/engine block)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated (check engine light)
- Transmission may be stuck in one gear or go into limp/limitation mode
- Harsh, delayed or erratic shifting
- Loss of certain gear ranges or failure to shift into intended gear
- Stored transmission-related fault codes and reduced drivability
What to check
- Connect a diagnostic scan tool and read all stored codes and freeze-frame data
- Attempt to command/actuate shift solenoid E with a scan tool and observe response
- Inspect transmission fluid level and condition (burnt smell, contamination)
- Visually inspect solenoid connector and harness for corrosion, damage, or loose terminals
- Check battery and charging system voltage (battery fully charged, alternator output stable)
- Check relevant fuses and relays for the transmission control/solenoid circuits
Signal parameters
- Typical coil resistance (varies by transmission): roughly 10–40 Ω (compare to manufacturer spec)
- Supply voltage: battery voltage (~12 V) present on reference side with ignition ON
- Control method: PCM/TCM usually grounds or supplies PWM to modulate solenoid (0–100% duty cycle)
- Typical PWM frequency range: tens to a few hundred Hz (manufacturer specific)
- Typical current draw: ~0.2–2.0 A depending on solenoid design
Diagnostic algorithm
- Connect an appropriate scan tool. Record stored codes, freeze-frame data and live data for shift solenoid E. Note vehicle conditions when fault set (RPM, temp, gear).
- Attempt to command/activate shift solenoid E from the scan tool. Observe live data and listen/feel for actuation. If no response, continue electrical checks.
- Visually inspect the solenoid connector and harness for corrosion, bent pins, heat damage or water intrusion. Repair or replace any damaged connectors or harness sections.
- Check battery voltage with ignition ON and while cranking; verify charging system is healthy. Replace/repair as needed. Check transmission fuses/relays and replace if faulty.
- Disconnect the solenoid connector and measure coil resistance across the solenoid terminals. Compare to manufacturer spec. An open or very high resistance indicates a failed coil; a near-zero resistance suggests a short.
- With connector connected, backprobe the circuit while commanding the solenoid. Verify reference supply (battery voltage) on one terminal and PCM switching/PWM or ground on the other when commanded. Use an oscilloscope to confirm PWM waveform if available.
- Wiggle test the wiring from the solenoid to the PCM/TCM (especially through the bellhousing area) while monitoring the live data or scan tool for intermittent faults. Repair any chafed or broken wires.
- If wiring, connectors, and power/ground are good but the solenoid fails to respond or resistance is out of range, remove and bench-test or replace the solenoid assembly. Follow safe lift/jack and transmission access procedures for your vehicle.
- After repairs, clear codes and perform a road test/shift verification. Re-scan to confirm the P0773 does not return. If code returns and wiring/solenoid verified, consider PCM/TCM diagnosis or replacement and check for manufacturer TSBs.
- Consult factory wiring diagrams and technical service information before replacing the PCM/TCM. Avoid replacing control modules until all wiring and component tests are complete.
Likely causes
- Damaged/loose connector or wiring to shift solenoid E
- Failed shift solenoid E (coil open/short or sticky valve)
- Chafed wiring in the transmission harness (common at bellhousing)
- Low system voltage or blown fuse affecting solenoid supply
- PCM/TCM driver fault (less common)
Fault status
Status
P0773 — Shift Solenoid E Electrical: The transmission control module has detected an electrical fault in the Shift Solenoid E circuit. Possible causes include open/short wiring, poor connector, failed solenoid, low voltage, or control module driver issues.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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