John Deere 190.18 – PTQ / PTR / PTP / TIP: Engine Speed Low / Engine Speed Missing During Shift

Triggered when the control unit detects that the engine speed signal has dropped below a critical threshold (typically below 300-400 RPM) for more than 2 to 3 seconds. This most commonly occurs when the engine stalls under a heavy load, but it can also be caused by a loss of the engine speed signal on the CAN bus due to a faulty sensor or wiring issue.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5085E
• 5090E
• 5090EL
• 5100E
• 6100D
• 6115D
• 6130D
• 6140D
• 7810
• 7800
• 8100
• 8200
• 6R Series
• 7R Series
• 8R Series
• 4520
• 6400
• 7700
• 9000 Series Combines

1. 1

   Verify Operating Conditions: Determine if the tractor simply stalled due to severe overloading or operator error.

2. 2

   Inspect the Engine Speed Sensor: Locate the engine speed sensor (crankshaft position sensor). Check the sensor tip for dirt, metal shavings, or physical damage. Ensure it is properly aligned and seated.

3. 3

   Check Wiring and Connections: Inspect the wiring harness and connectors between the engine speed sensor, the Engine ECU, and the PTQ/PTR module. Look for corrosion, loose pins, or chafed wires that could cause a signal drop.

4. 4

   Test Sensor Circuitry: Use a multimeter to test the engine speed sensor circuitry for proper resistance and verify there are no short or open circuits causing the signal loss.

5. 5

   Check for Accompanying Codes: Check the Engine ECU for related codes (such as 000637.xx for Crankshaft Position Sensor signal issues). If the Engine ECU is losing the sensor signal, the PTQ will subsequently log 000190.18.

1. 1

   Operator Recovery (Stall/Overload)

   If the code was caused by stalling, reduce the engine load. Return the shift lever to Neutral or Park, increase the engine RPM, and cycle the key switch to recover the vehicle system. Clear the code and test drive.

2. 2

   Clean the Sensor

   If the code persists without stalling, remove the engine speed sensor, clean the magnetic tip, and reinstall it. Re-check the connection.

3. 3

   Repair the Harness

   If multimeter testing reveals an open or short in the wiring harness, repair or replace the damaged section of the harness.

4. 4

   Replace the Sensor

   If the wiring is intact but the sensor fails resistance/voltage tests (or if the signal drops out intermittently during operation), replace the engine speed sensor.

5. 5

   Software Update

   If the sensor and wiring are good, contact a John Deere dealer. Some older software versions had overly sensitive thresholds that caused nuisance 190.18 codes; a software flash to the PTQ or Engine ECU may be required.