Allison 1000 P0717 ISS No Signal: Quick Fix Guide

P0717 means your Allison Input Speed Sensor has no signal at all. Different from P0716 (range/performance). Usually means dead sensor or broken wire.

P0716 vs P0717

P0716:

  • ISS reports wrong value
  • Outside expected range
  • Still some signal

    • P0717:

  • ISS reports no signal
  • TCM sees zero
  • More definitive failure

    • Common causes

    #1: ISS sensor failed

  • Internal coil dead
  • Most common cause

    • #2: Wiring broken

  • Internal harness
  • Or external chafe

    • #3: Reluctor wheel damage

  • Rare
  • Internal mechanical issue

    • Symptoms

    • Limp mode (3rd or 4th gear only)
    • No upshifts
    • Sometimes harsh engagement
    • Tow/Haul light flashing

    Diagnosis

    Step 1: Check connector

  • External harness at trans
  • Look for damage

    • Step 2: Resistance check

  • Disconnect ISS
  • Ohm across terminals
  • Open = sensor or wiring broken
  • Spec: 600-1200 ohms

    • Step 3: Continuity test wiring

  • From sensor to TCM
  • Verify no breaks

    • Cost

    ISS sensor:

  • $40-$90 part
  • Install requires pan drop
  • Total DIY: $80-$140
  • Shop: $290-$540

    • Install

    Bottom line

    P0717 is usually:

  • Bad sensor (70%)
  • Broken wire (25%)
  • Damaged reluctor (5%)

    • Cheap fix path:

  • Check connector first
  • Replace ISS sensor
  • Total under $300 DIY

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