P0732

Code

HUMMER P — Powertrain

Incorrect 2nd Gear Ratio

Brand: HUMMER

Type: P — Powertrain

Views: UK: 8 EN: 15 RU: 23

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Low or contaminated transmission fluid
Faulty or sticking 2nd gear shift solenoid (shift solenoid B/2)
Faulty transmission wiring or connector to solenoid(s) or speed sensors
Internal valve body contamination or stuck valve
Worn or damaged 2nd gear clutch pack, band, or planetary gear set
Torque converter internal wear or slip

Symptoms

MIL/Check Engine Lamp illuminated
Harsh, delayed, or failed shift into 2nd gear
Transmission slipping or unusual revving in 2nd gear
Reduced acceleration or limp-in-gear behavior
Abnormal engine RPM vs vehicle speed during 2nd gear
Transmission may enter limp mode or default to a single gear

What to check

Read and record DTCs and freeze frame data with a capable scanner; note related transmission and engine codes
Scan live data for transmission commanded vs actual gear, input and output shaft speeds, and calculated gear ratio
Verify transmission fluid level, color and smell; check for metal debris on pan/magnet (if serviceable)
Inspect wiring and connectors for shift solenoids and speed sensors for damage, corrosion or loose pins
Perform a road test with live data logging to observe behavior entering and during 2nd gear
Check for service bulletins or TCM software updates for this code on HUMMER model

Signal parameters

Transmission input shaft speed (RPM)
Transmission output shaft/vehicle speed sensor (RPM or kph/mph)
Calculated 2nd gear ratio (input RPM ÷ output RPM) vs target ratio from TCM
Shift solenoid 2 (2nd gear) status and duty cycle
Line/ hydraulic pressure (transmission line pressure) during shift
Torque converter clutch (TCC) status and slip indication

Diagnostic algorithm

Retrieve all transmission and engine codes; record freeze frame and live data. Check for related codes (speed sensors, solenoids, torque converter).
Visually inspect transmission fluid: level, color, odor. Top or replace fluid if low or severely degraded; inspect pan and magnet for metal debris. Use manufacturer fluid spec.
Inspect wiring harness and connectors for shift solenoids and speed sensors. Repair any damage and clear corrosion; retest.
With scanner, monitor input & output speeds and calculated gear ratio during a controlled road test. Confirm the ratio error occurs and note conditions (load, throttle).
Test shift solenoid 2 electrically: check resistance/continuity against spec, and command solenoid on/off with scanner while monitoring response. Replace if out of spec or non-responsive.
If solenoid and wiring pass, perform a hydraulic pressure test (line pressure, apply pressures) per service manual to verify proper clutch application and line pressure in 2nd gear.
Inspect valve body for contamination or sticking valves; clean or rebuild valve body if required following service procedures.
If hydraulic and electrical systems are good, inspect internal transmission components (clutch pack, band, planetary gears) — may require partial or full transmission disassembly.
Check input/output speed sensor operation and replace if faulty. Verify TCM software version and perform any recommended updates or adaptations/relearn procedures.
After repair, clear codes and perform a full verification road test and re-scan to confirm code does not return.

Likely causes

Low fluid level or degraded fluid causing improper line pressure and slipping
Shift solenoid 2 electrical fault or hydraulic sticking preventing proper clutch application
Valve body contamination or sticking valve altering hydraulic routing for 2nd gear
Worn clutch pack or band that cannot hold 2nd gear under load
Faulty input/output speed sensor or connector causing wrong ratio calculation

Fault status

⚠️ Status

Transmission — Incorrect 2nd gear ratio detected. Reduced performance or drivability; inspection and repair recommended.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 2-6 hours

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P0732 — Incorrect 2nd Gear Ratio