Applicable Systems
OBD-II
Symptoms
Transmission input speed sensor signal fault; TCM cannot calculate gear ratio; may default to limp mode.
Possible Causes
- Input speed sensor internal failure
- Sensor wiring open/short
- Sensor air gap incorrect
- Drive plate reluctor damaged
Troubleshooting Steps
- Step 1: Check input speed sensor resistance
Resistance within spec (300-800 ohm) - Step 2: Inspect sensor wiring
Wiring intact - Step 3: Check sensor air gap
Air gap within spec - Step 4: Monitor sensor signal with scanner
Signal present when engine running - Step 5: Replace sensor if signal absent
Signal present with new sensor
How to Reset
Clear with OBD-II scanner after sensor replacement.
Common Replacement Parts
- Transmission Input Speed Sensor (OEM spec)
Frequently Asked Questions
- Q: What is input speed sensor?
Measures turbine speed (between torque converter and transmission). TCM uses it with output speed sensor to calculate gear ratio and detect slip.
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Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II
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