Allison Internal Speed Sensor Replacement: P0716/P0717 DIY Fix

Allison internal turbine speed sensor failure is the #1 cause of P0716 and P0717 codes on Duramax trucks. Sensor sits inside the pan area. Pan-drop fix, 2-3 hours, $80-$150 total.

Two speed sensors on Allison

Output speed sensor (external):

  • Mounts on tailshaft / transfer case
  • Easy 15-minute swap
  • P0722, P0723 codes
  • Read our External sensor DIY

Input / Turbine speed sensor (internal):

  • Inside the pan area
  • Drop pan to access
  • P0716, P0717 codes
  • This article covers this one

What the turbine speed sensor does

Function:

  • Reads input shaft RPM
  • TCM compares to engine RPM
  • Detects torque converter slip
  • Detects clutch slip

    • Critical for:

  • Shift timing
  • TCC lockup management
  • Limp mode triggers
  • Adaptive learn updates

    • Symptoms of failure

    Drive symptoms:

  • Limp mode (stuck in 4th or 5th)
  • Harsh shifts
  • No TCC lockup
  • Sometimes no upshift

    • Codes:

  • P0716 - input speed circuit erratic
  • P0717 - input speed no signal
  • P0722 sometimes paired (if both sensors)

    • Why it fails

    Wire chafing:

  • Internal harness rubs case
  • Wire eventually breaks
  • Common 100k-180k miles

    • Sensor wear:

  • Magnetic pickup wears
  • Signal weakens
  • Eventually no signal

    • Connector corrosion:

  • Pin oxidation
  • Resistance increases
  • Intermittent signal

    • Diagnosis

    Step 1: Pull DTCs

  • P0716 + P0717 confirm input sensor
  • P0722 + P0723 would be output sensor
  • Cannot tell which by limp mode alone

    • Step 2: Live data

  • Input shaft RPM should match engine RPM in 4th gear
  • 0 RPM displayed = no signal
  • Erratic = wire damage

    • Step 3: Resistance test

  • Pull pan to access
  • Backprobe at sensor connector
  • Spec: 200-400 ohms typical
  • Open or short = bad sensor

    • Replacement parts

    OEM AC Delco sensor:

  • AC Delco 29539442 or similar
  • $60-$120 part
  • Same as factory

    • Internal harness (if damaged):

  • $80-$150
  • Replace if chafed
  • Inspect before reusing

    • Pan gasket:

  • OEM reusable on later units
  • Cork on older
  • $15-$30

    • Tools needed

    • 15mm socket (pan bolts)
    • 10mm socket (sensor bracket)
    • Drain pan (16+ qt capacity)
    • Torque wrench
    • Pliers (connector tabs)

    Step-by-step procedure

    Step 1: Prep

  • Truck on level ground
  • Cool trans (overnight ideal)
  • Get drain pan ready
  • Allison filter and gasket on hand

    • Step 2: Drop pan

  • Drain plug if equipped: drain first
  • Otherwise: loosen all bolts, drop pan
  • Lose 14-18 quarts fluid
  • Pan has alignment dowels

    • Step 3: Remove filter

  • Spin-off internal filter
  • Drains a few more quarts
  • Discard old filter

    • Step 4: Locate input sensor

  • Mounted on internal harness
  • Wires lead up to sensor body
  • Look near torque converter side of pan area
  • Disconnect electrical

    • Step 5: Remove sensor

  • Usually one 10mm bolt
  • Bracket releases sensor
  • Pull sensor down
  • Note O-ring placement

    • Step 6: Inspect harness

  • Look for chafing
  • Check wire insulation
  • Replace harness if damaged
  • Wrap abrasion sleeve if rubbing

    • Step 7: Install new sensor

  • New O-ring lubed with ATF
  • Press sensor into bore
  • Bracket on, bolt in
  • Torque 8-10 ft-lb

    • Step 8: Reconnect electrical

  • Connector clicks on
  • Pull back to verify locked
  • Route harness same as original

    • Step 9: New filter

  • Lube O-ring
  • Spin on by hand
  • 1/4 to 1/3 turn past contact
  • Hand tight only

    • Step 10: Reinstall pan

  • New gasket (or clean old reusable)
  • Pan in alignment dowels
  • Bolts in 4-corner sequence
  • Torque 17 ft-lb typical

    • Step 11: Refill TES-295

  • Start with 12 quarts via dipstick
  • Start engine
  • Cycle gears (P/R/N/D)
  • Check level cold
  • Drive 10-15 minutes to warm
  • Top off hot
  • Total: 14-18 quarts

    • Step 12: Clear codes

  • Scanner clears stored DTCs
  • Drive cycle to verify
  • 20+ mile drive

    • Cost

    DIY:

  • Sensor: $60-$120
  • Pan gasket: $15-$30
  • Filter (do it anyway): $35-$50
  • 14-18 qts TES-295: $280-$540
  • Time: 2-3 hours
  • Total: $390-$740

    • Shop:

  • Parts: $390-$740
  • Labor: $200-$400
  • Total: $590-$1140

    • Common mistakes

    Forgetting to clear codes:

  • TCM remembers fault
  • Stays in limp mode
  • Always clear after fix

    • Using wrong fluid:

  • NEVER Dexron VI in Allison
  • NEVER ATF+4
  • TES-295 or TES-668 only

    • Reusing damaged harness:

  • If chafed - replace
  • Will fail again soon
  • $80-$150 insurance

    • Skipping filter:

  • Pan is already off
  • Cheap insurance
  • Always replace at sensor swap

    • What if codes return

    P0716/P0717 returns immediately:

  • Wiring fault
  • Check external connector at trans
  • Test continuity to TCM

    • New codes appear:

  • Drive cycle to clear adapt
  • 50-100 mile drive
  • Should resolve

    • Different codes:

  • Reset cleared coincidental codes
  • Diagnose new ones separately

    • While you have it apart

    Recommended:

  • Output speed sensor too ($40-$80)
  • Both sensors aging together
  • Pan magnet inspection
  • Internal harness inspection

    • Read our:

  • Allison filter service guide
  • Allison limp mode causes

    • Bottom line

    Pan-drop DIY fix:

  • $390-$740 (mostly fluid cost)
  • 2-3 hours
  • Restores all functions

    • Combines with filter service:

  • Pan is already off
  • Filter is in pan area
  • One trip, two jobs

    • Avoid limp-mode rebuild misdiagnosis:

  • $5000+ rebuild from misdiagnosis
  • Always try sensors first
  • Sensors cheap, rebuilds expensive

    • Need Allison input speed sensor, output sensor, or filter kit? Visit our Allison catalog. OEM sensors, complete filter kits, internal harnesses. Free shipping over $70.

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