P1836

What it means

P1836 is a manufacturer-specific code. For this entry it means the control unit has detected a fault in the circuit of the transfer case front shaft speed sensor on a four-wheel-drive or all-wheel-drive vehicle. The signal was missing, implausible or out of range, or did not match other speed inputs such as wheel speed or output shaft speed. The exact setting conditions vary by manufacturer and model, so check the maker's data for the vehicle.

Symptoms

• Warning light on, which may be the engine, transmission or 4WD/AWD light depending on the vehicle
• Four-wheel-drive or all-wheel-drive system disabled or defaulting to a limited mode
• Harsh, delayed or erratic gear changes on some models
• Speedometer or speed-related functions behaving erratically
• Transfer case mode changes refused or not completing
• Drivetrain binding or noise on tight turns if the system cannot manage front and rear speed difference

Possible causes

• Faulty transfer case front shaft speed sensorlikely
• Damaged, chafed, corroded or broken wiring to the sensor (open circuit, short to earth or short to voltage)likely
• Poor connector contact, water ingress or corrosion at the sensor or control unit pluglikely
• Contamination of the sensor tip with metallic debris or damaged tone ring/reluctor in the transfer casepossible
• Low or contaminated transfer case fluid affecting internal wear or sensor signalpossible
• Fault in the transmission or transfer case control unitrare
• Outdated control unit software where a manufacturer bulletin lists it as a causerare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting speed, gear and drive mode when the fault set, and check for related wheel speed or output speed codes
2. Confirm the code definition against the manufacturer data for the exact make, model and year, as the meaning of P1836 differs between manufacturers
3. Visually inspect the sensor, its wiring and routing for chafing, heat damage, oil contamination, and impact or corrosion damage
4. Check the connector at the sensor and control unit for bent, pushed-out or corroded pins and water ingress
5. Check the transfer case fluid level and condition, looking for metal particles or a burnt smell
6. Using live data, compare the front shaft speed reading with wheel speed and output speed while driving or on a lift, as the maker permits
7. Test the sensor circuit for supply, signal, earth, continuity and shorts, and check the sensor resistance or output against specification
8. Inspect the sensor tip and tone ring for damage or debris, and check for any applicable software update or technical bulletin

How to fix

• Replace the transfer case front shaft speed sensor if it fails electrical or signal tests
• Repair or replace damaged wiring and terminals, and secure the harness away from heat and moving parts
• Clean, repair or replace corroded or loose connectors and seal them against water
• Correct the transfer case fluid level or renew the fluid with the correct specification, and repair any cause of wear or contamination
• Repair or replace a damaged tone ring or transfer case internals if found
• Update the control unit software only where the manufacturer lists it as the fix, or replace a confirmed faulty control unit

Can I keep driving?

This code for other makes

• P1836BuickKick-Down Switch Failed Open
• P1836CadillacKick-Down Switch Failed Open
• P1836ChevroletKick-Down Switch Failed Open
• P1836GMKick-Down Switch Failed Open
• P1836GMCKick-Down Switch Failed Open
• P1836OldsmobileKick-Down Switch Failed Open
• P1836SaturnKick-Down Switch Failed Open

Nearby codes

• P1835OtherTransmission Transfer Case Differential Lock-Up Solenoid Short Circuit To Ground
• P1837OtherTransmission Transfer Case Rear Shaft Speed Sensor Circuit Failure