P1667

Code

HUMMER P — Powertrain

Reverse Inhibit Solenoid Control Circuit

Brand: HUMMER

Type: P — Powertrain

Views: UK: 13 EN: 13 RU: 11

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Page language: EN

Causes

Open or high-resistance wiring between PCM/TCM and reverse inhibit solenoid
Short to ground or short to battery in the solenoid control circuit
Corroded, damaged or loose connector at the solenoid or PCM/TCM
Failed reverse inhibit solenoid (coil failure)
Blown fuse or faulty relay supplying the solenoid circuit
Poor chassis or circuit ground

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Vehicle will not engage reverse or transfer-case reverse inhibit function
Transmission or transfer case stuck in current gear or mode
Intermittent loss of reverse engagement
Possible shift irregularities or limp-home behavior
No obvious mechanical noise from solenoid when commanded

What to check

Retrieve all stored codes and freeze-frame data with a scan tool; note history and related transmission / transfer-case codes
Check Technical Service Bulletins (TSBs) for vehicle-specific guidance
Perform visual inspection of solenoid connector, wiring harness and PCM/TCM connector for damage, corrosion or water intrusion
Inspect fuses and relays that supply the solenoid circuit
Backprobe solenoid connector and verify reference voltage (supply) and ground/command while commanding solenoid with a bi-directional scan tool
Use an ohmmeter to measure solenoid coil resistance with connector disconnected

Signal parameters

Activation voltage: approximately battery voltage when commanded ON (nominally ~9–14 V) — verify vehicle-specific value
Coil resistance (typical range): ~10–50 ohms (vehicle-specific; consult service data) — infinite/open indicates open coil, very low (near 0) indicates short
Command type: switched ground or switched +12 V from PCM/TCM depending on vehicle — confirm with backprobe
When commanded, current should increase; an open circuit will show no current, a short will show excessive current or a blown fuse

Diagnostic algorithm

Connect a scan tool, record P1667 and any related codes, capture freeze-frame and live data. Clear codes and attempt to re-create.
Visually inspect harness, connectors, and grounds for damage, corrosion or signs of water intrusion. Repair obvious damage first.
Check related fuses and relays; replace as needed.
With ignition ON, backprobe solenoid connector: verify battery supply (if present) and control/ground circuit state. Note voltages with solenoid not commanded and while commanding ON via scan tool.
Unplug solenoid and measure coil resistance with an ohmmeter. Compare to vehicle spec. If out of range, replace solenoid.
If coil resistance is normal, check for continuity between the control pin at the solenoid connector and the PCM/TCM control pin. Repair any open or shorted wiring.
If wiring checks good, command the solenoid while monitoring voltage/current at the connector. If the module never supplies the command, suspect PCM/TCM output fault and verify module grounds and power supplies before replacement.
After repairs, clear codes, command the solenoid and perform a road or function test to confirm normal operation and that the DTC does not return.
If fault is intermittent, perform extended wiggle/drive testing or harness securing and re-test.

Likely causes

Broken or chafed wire to the solenoid
Corroded/poor connector pins at the solenoid or module
Failed solenoid coil
Blown fuse or bad relay

Fault status

⚠️ Status

P1667 - Reverse Inhibit Solenoid Control Circuit: detected open/short/high resistance or no command to the reverse inhibit solenoid. Inspect wiring, connectors, fuse/relay and solenoid.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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