C0750 on 2019-2025 Cadillac XT4: Causes for TPMS, Key Fob, and No-Start Issues

What's Unique About the 2019-2025 Cadillac XT4

On the Cadillac XT4 and similar modern GM platforms, this is not just a simple tire pressure code. The same antennas and central receiver (RCDLR) used to read tire pressures are also used to detect the key fob's presence for keyless entry and starting the engine. A failure setting code C0750 can, therefore, disable the passive entry function on the driver's door and, more critically, prevent the car from starting, triggering a 'No Remote Detected' message and illuminating the security light. This is a known issue documented in manufacturer service bulletins for many GM vehicles.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• "Service Tire Monitor System" message on the Driver Information Center (DIC)
• TPMS warning light flashes for about a minute and then stays on solid
• "No Remote Detected" message on the DIC, especially when trying to start the vehicle.
🎬 Watch this walkthrough for fixing 'No Remote Detected' messages.
• Inability to start the engine (no crank/no start condition).
• Security light is illuminated on the instrument panel
• Passive/keyless entry does not work on the driver's door
• Remote key fob functions (lock/unlock/remote start) may work intermittently or not at all.
• Dashes (---) displayed for the left front tire pressure reading, and possibly other tires as well.

Most Likely Causes

1. Failed Remote Control Door Lock Receiver (RCDLR) 🔴 High Probability This module is a known failure point on many modern GM vehicles, as documented in TSB 16-NA-396. It processes signals from both the TPMS sensors and the key fobs, and an internal fault can cause widespread communication issues, setting multiple TPMS codes and causing keyless entry/start problems simultaneously.
   How to confirm: If you have C0750 along with other TPMS codes (C0755, C0760, C0765) and are also experiencing key fob issues like 'No Remote Detected' or passive entry failure, the RCDLR is the most likely culprit. This is the classic symptom pattern described in GM service bulletins.
   Typical fix: Replace the RCDLR module and have it professionally programmed to the vehicle. The module is typically located behind a rear trim panel.
   Est. part cost: $100-$200
2. Failed Left Front TPMS Sensor 🔴 High Probability TPMS sensors contain non-replaceable batteries that have a finite lifespan, typically 7-10 years. They can also be damaged during tire service or by road impacts. The XT4 uses a 433 MHz sensor.
   How to confirm: If C0750 is the only code present and your key fob functions are working normally, the issue is most likely the sensor itself. A tire shop can use a specialized tool to test the sensor's signal output and battery level.
   Typical fix: Replace the TPMS sensor inside the left front tire and perform the TPMS relearn procedure.
   Est. part cost: $40-$90
3. Wiring Harness or Connector Issue 🟡 Medium Probability The low-frequency antennas and their wiring are often located in or behind the bumper covers or wheel well liners, making them susceptible to damage from road debris, moisture, and corrosion. TSB 16-NA-061 details how disconnected coax cables for the RCDLR antenna can cause these exact symptoms.
   How to confirm: Visually inspect the wiring harness and coax cable leading to the LF low-frequency antenna and the RCDLR module for any signs of chafing, breaks, or corrosion in the connectors.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the corroded connector.
   Est. part cost: $10-$50

Rare But Worth Checking

• Radio Frequency (RF) Interference: Unplug any aftermarket electronic devices, such as phone chargers, dash cams, LED lighting, or toll passes. TSB PIC5650K specifically warns that these devices can interfere with the 315 MHz, 433 MHz, and 125 kHz frequencies used by the TPMS and keyless entry systems, causing intermittent issues.

Diagnosis Steps

1. Verify the symptoms. Check if the keyless entry and push-button start are working correctly. Note if the 'No Remote Detected' message appears. If it does, try placing the fob in the designated transmitter pocket in the center console to start the car.
🎬 Watch: How to start your XT4 with a dead key fob.
2. Scan the Body Control Module (BCM) and Remote Control Door Lock Receiver (RCDLR) for all DTCs. Note if C0750 appears alone or with other codes like C0755/C0760/C0765 or B-codes related to the security system. Look for specific symptom bytes like :29 (Too Few Pulses) or :03 (Low Voltage).
3. If multiple TPMS codes and key fob/starting issues are present, suspect the RCDLR module or its wiring as the primary cause per TSB 16-NA-396.
4. If only C0750 is present and the key fob works perfectly, the left front TPMS sensor is the most likely cause.
5. Use a TPMS diagnostic tool to attempt to activate and read the signal from the left front sensor. If it fails to respond, the sensor is likely bad.
6. Inspect the wiring and connector for the LF low-frequency antenna (often located in the front bumper area) and the RCDLR module for any visible damage, corrosion, or looseness. TSB 16-NA-061 points to loose antenna connections as a possible cause.
7. Check for Radio Frequency Interference (RFI) by removing all aftermarket electronics (chargers, dashcams, etc.) and re-testing, as advised by TSB PIC5650K.
8. If the sensor is good and wiring is intact, the fault is likely the RCDLR module, which will require replacement and programming.

Parts You'll Likely Need

• Remote Control Door Lock Receiver (RCDLR) (OEM #84504723, 84861631 (verify by VIN)) — This module is a common failure point that causes C0750 along with key fob and no-start issues, as documented in GM TSBs.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $100-$200
  Aftermarket price range: $70-$150
• Tire Pressure Monitor Sensor (TPMS) (OEM #13516165, 84961888 (for 2019-2021), 85134222 (for 2022+) (verify by VIN)) — This is the most common fix when C0750 appears alone without any key fob or starting problems. The sensor's internal battery dies over time. The XT4 uses a 433 MHz sensor.
  Trusted brands: ACDelco, Schrader, Continental, Huf
  OEM price range: $60-$110
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• C0755, C0760, C0765 — These codes correspond to the Right Front, Left Rear, and Right Rear tire pressure sensors. When they appear together with C0750, it strongly suggests a failure of the central receiver (RCDLR) rather than all four sensors failing simultaneously, as detailed in TSB 16-NA-396.
• B3055, B3060, B3935 — As noted in TSB #PIC5650M and PIC5650K, these codes relate to the keyless entry and immobilizer system. Their presence alongside C0750 confirms the issue is tied to the vehicle's security and starting system, not just the tires.

Technical Service Bulletins (TSBs) & Recalls

• PIC5650M: Links C0750 and other codes to a no crank/no start/start-stall condition with the security light on, often caused by RF interference.
• 16-NA-396: While not listing the XT4 specifically (released prior), it details the exact same symptoms (TPMS codes, 'No Remote Detected', passive entry failure) on related GM platforms and identifies the cause as an internal RCDLR failure, instructing technicians to replace the module.
• 16-NA-061: Details how poor or disconnected antenna connections for the RCDLR can cause TPMS messages and poor key fob range, another potential cause for C0750.

Platform-Specific Known Issues

• Per NHTSA Technical Service Bulletin #PIC5650M, the 2019-2025 Cadillac XT4 can set code C0750 in conjunction with an intermittent no crank, no start, or a start-and-stall condition, accompanied by the security light.
• Owner Experience: RCDLR Failure: An owner of a 2020 XT4 on CadillacForums.com reported intermittent 'No Remote Detected' messages and failure to start. The dealer found codes C0750, C0755, C0760, and C0765 stored. The fix was replacing and programming the Remote Control Door Lock Receiver (RCDLR) module, which resolved all symptoms.

Mechanic-Grade Diagnostic Values

• TPMS Sensor Signal Strength — expected: A TPMS tool should display a 'good' signal strength, often represented as more than 1/4 of the signal graph on the tool's display.. Failure: No signal or a very weak signal that requires multiple activation attempts.

Hidden / Shadow Codes Worth Checking

• C0750:29: Too Few Pulses. This is a common symptom byte indicating the RCDLR is not receiving the expected number of signal transmissions from the sensor. It's explicitly mentioned in TSB 16-NA-396 and strongly points to an RCDLR or communication issue. (see via GM GDS2/Tech2 or a high-end aftermarket scan tool capable of reading manufacturer-specific symptom codes.)
• C0750:03: Low Voltage. This symptom byte indicates the RCDLR has detected that the TPMS sensor's internal battery is failing. (see via GM GDS2/Tech2 or a high-end aftermarket scan tool.)
• C0750:08: Signal Invalid. This indicates the data being received from the sensor is corrupt or not in the expected format. (see via GM GDS2/Tech2 or a high-end aftermarket scan tool.)

Scan Tool Commands That Help

• GM GDS2: Module Diagnostics -> RCDLR -> Control Functions — This allows a technician to perform bidirectional controls to test the system. For example, using the 'simulate mode' with a TPMS tool to learn simulated sensor transmissions can verify if the RCDLR itself is capable of receiving and processing signals, helping to isolate the fault to the sensor or antenna circuit.
• GM GDS2: Vehicle DTC Information (Full Scan) — To check all modules for codes. The presence of codes in both the RCDLR (C-codes) and BCM (B-codes) simultaneously confirms the problem is system-wide and not just an isolated tire sensor.
• GM GDS2: Module Diagnostics -> RCDLR -> Data Display — To observe live data parameters, such as the 'Pressure Sensor Mode'. A technician can watch this parameter to see if it changes from 'Wake' to 'Drive' or 'Rolling' mode when the vehicle is driven over 25 mph. If it doesn't change for the suspect sensor, it points to a faulty sensor.

Wiring & Ground Locations

• RCDLR Module — On similar GM platforms like the Yukon and Acadia, the RCDLR is located in the rear of the vehicle, typically behind the driver's side (left side) rear quarter trim panel, near the D-pillar.. This is the physical location of the module that is the most common cause of failure. Access is required for visual inspection of its connections (especially the coax antenna cable) and for replacement.
• RCDLR Antenna System — Per TSB 16-NA-061, the system consists of the RCDLR, a coax cable, an antenna amplifier module, and the antenna itself (often in the right rear glass). Key connection points to check are the coax at the RCDLR, the coax at the amplifier, and the amplifier at the glass.. A disconnected coax cable at the RCDLR can cause all TPMS and key fob functions to fail. A disconnect further away, at the amplifier, may only cause issues with sensors farthest from the module, like the left front (C0750).
• GM Ground Numbering (G###) — GM uses a standard numbering system for grounds. G1xx grounds are in the engine bay, G2xx are in the front passenger area/dash, G3xx are in the rear seat area, and G4xx are in the rear cargo/tailgate area.. A faulty ground for the RCDLR (likely a G3xx or G4xx series ground) can cause intermittent operation and communication codes. Knowing the numbering convention helps locate the correct ground point from a wiring diagram.

OEM Part Supersession History

• 13516165, 84961888 → 85134222 — Part update/revision for newer model years.
  Heads up: The TPMS sensor part number appears to have changed for the 2022 model year and newer XT4s. Part number 85134222 is specified for 2022+ models. While they may be physically similar, using the wrong sensor could lead to programming or operational issues. Always verify the correct part number by VIN.

Model Year Variations Within This Range

• 2022-2025: The OEM TPMS sensor part number changes to 85134222 for models from 2022 onwards. Earlier models (2019-2021) use previous part numbers like 13516165 or 84961888.