C1150 — Two Speed Rear Axle Input Switch Circuit Short to Vbatt #

Note: The description of DTC C1150 may vary depending on the vehicle manufacturer (OEM).

• Ford: Two Speed Rear Axle Input Switch Circuit Short to Battery Voltage
• GM: Two Speed Rear Axle Switch Circuit Shorted High
• Chrysler: Rear Axle Range Switch Circuit Short to Voltage

Summary of code C1150 #

C1150 indicates a fault in the electrical circuit related to the two-speed rear axle input switch, specifically a short to battery voltage (Vbatt). This switch allows the vehicle’s control module to detect or change between different gear ranges in the rear axle, particularly in trucks or vehicles equipped with dual-range axles. When the circuit is shorted to battery voltage, the system detects an abnormally high signal where it expects a low or variable input, triggering the code. This can lead to issues with shifting or engagement of the rear axle ranges, potentially affecting drivability and towing capabilities. Prompt attention is recommended to prevent further electrical or mechanical damage.

Common symptoms for code C1150 #

Drivers may notice several warning signs when C1150 is present. These symptoms often revolve around the vehicle’s ability to switch between axle ranges or may manifest as dashboard warnings. In some cases, issues may be subtle, while in others, they can quickly impact performance:

• Warning light illuminated (ABS, traction, or specific axle indicator)
• Failure to shift between high and low axle ranges
• Unusual clicking or relay noises from the axle area
• Reduced towing or off-road capability
• General loss of rear axle function in certain modes

Likely causes for code C1150 #

The most common causes of a C1150 code are related to electrical faults or component failures within the rear axle switching system. Here’s what technicians typically find, in order from most to least frequent:

1. Shorted wiring or harness connected to the rear axle input switch
2. Faulty two-speed rear axle input switch
3. Corroded, loose, or damaged electrical connectors at the axle switch
4. Short to power inside the vehicle’s power distribution box or fuse panel
5. Failure of the control module managing axle range switching

Step-by-step diagnostic process for C1150 #

A thorough and methodical approach is essential to isolate the root cause of C1150. Follow these steps to ensure nothing is overlooked:

1. Verify the code using a professional scan tool and note any related DTCs.
2. Perform a visual inspection of the rear axle switch and wiring harness for obvious damage, chafing, or corrosion.
3. Check the electrical connectors for signs of moisture, debris, or bent pins.
4. Measure voltage at the input switch with a multimeter; compare readings with OEM specifications.
5. If voltage is abnormally high, trace the harness back toward the fuse panel or control module looking for shorts to battery voltage.
6. Test the input switch itself for internal shorts or open circuits using a continuity test.
7. If all wiring and switch tests pass, check the control module for faults or update requirements.
8. Clear the code and road test the vehicle, monitoring live data to confirm repair.

Possible repairs for code C1150 #

Depending on the cause identified during diagnostics, the following repairs are commonly performed to resolve C1150:

• Repair or replace damaged wiring or connectors at the rear axle input switch
• Replace the faulty two-speed rear axle input switch
• Clean and secure all electrical connections at the switch and control module
• Repair or replace shorted wires in the harness leading to the power source
• Update or replace the vehicle’s control module if diagnosed as faulty

Can you drive with code C1150? #

Limited — It is often possible to drive with code C1150, especially if the vehicle remains in a usable axle range. However, you may lose the ability to switch between high and low ranges, which can be critical for towing or off-road driving. Extended operation with this code may also risk further electrical issues or damage to the axle actuators. It’s best to address the issue promptly to avoid being stranded or causing more expensive repairs.

Vehicles most commonly affected by C1150 #

Code C1150 is most often encountered on vehicles equipped with selectable two-speed rear axles, typically found in light to heavy-duty trucks and some commercial vehicles. The following models are frequently reported:

• Ford F-Series Super Duty (especially F-250, F-350 with dual-range axles)
• Chevrolet Silverado HD (models with two-speed rear axles)
• GMC Sierra HD
• Ram 2500/3500 with two-speed rear axle options
• Some Isuzu and International medium-duty trucks

Common mistakes & best practices for code C1150 #

Working with rear axle electrical systems can be tricky. Avoiding these frequent errors and following best practices will save time and prevent repeat failures:

• Overlooking visual inspection: Many skip checking for visible wire or connector damage, leading to unnecessary part replacements.
• Replacing the switch prematurely: Always test the wiring and connectors first—faulty wiring is more common than switch failure.
• Neglecting to check for moisture: Moisture in connectors can cause intermittent shorts; always inspect for water intrusion.
• Not clearing the code: After repairs, always clear the code and verify its return before considering the issue fixed.
• Ignoring manufacturer TSBs: Check for Technical Service Bulletins (TSBs) related to C1150 for known issues and updated procedures.

Quick FAQ for code C1150 #

Even experienced technicians and informed drivers have questions about this code. Here are quick answers to common concerns:

• Q: Does C1150 always mean the rear axle switch is bad?
  A: Not necessarily. Most often, the problem is with the wiring or connectors, not the switch itself.
• Q: Can a battery voltage spike trigger code C1150?
  A: Yes, sudden voltage spikes or shorts to battery power in the harness can cause this code, even if the switch is fully functional.