The Cadillac CTS, produced from 2003 to 2007, marked Cadillac’s entry into the competitive luxury sedan market with its distinctive design, sporty handling, and advanced features. Its electrical system, including the fuse box and relay components, played a crucial role in its overall functionality and reliability.
The fuse box in the Cadillac CTS from 2003 to 2007 contained various fuses designed to protect specific electrical circuits throughout the vehicle. These circuits powered essential components such as the engine control module, lighting systems, climate control, entertainment features, and more. Fuses were essential as they would interrupt the electrical flow in case of an overload or short circuit, preventing damage to sensitive components.
Relays in the Cadillac CTS acted as electrically operated switches that controlled high-current circuits. They facilitated the precise activation and deactivation of functions like the starter motor, fuel pump, air conditioning compressor, and power windows or seats. Efficient management of power distribution by relays contributed significantly to the vehicle’s overall performance and reliability.
Regular inspection and maintenance of the fuse box and relays were necessary to ensure the Cadillac CTS from 2003 to 2007 operated smoothly. This involved checking fuses for signs of wear or damage, ensuring secure relay connections, and promptly addressing any electrical issues that arose. Proper care of these components helped maintain the vehicle’s electrical integrity, enhancing safety and driving satisfaction for owners of the Cadillac CTS from 2003 to 2007.
MUST READ: DYI – How to Check Car Fuses?
(2003-2007) Cadillac CTS fuse box and relay with Diagram
WARNING
- Never replace a fuse with one that has a higher amperage rating.
- A fuse with a too-high amperage could damage the electrical part and cause a fire.
- On no account should fuses be repaired (e.g. patched up with tin foil or wire) as this may cause serious damage elsewhere in the electrical circuit or cause a fire.
- If a fuse blows repeatedly, do not keep replacing it. Instead, have the cause for the repeated short circuit or overload tracked and fixed.
- Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.
Cadillac CTS 2003-2007 fuse assignment
- Cigar lighter / power outlet fuses in the Cadillac CTS are located in the Engine compartment fuse box (see fuses “OUTLET” (Center Console Accessory Power Outlet) and “I/P OUTLET” (Instrument Panel Accessory Power Outlet)).
Year of production: 2003, 2004, 2005, 2006, 2007
Fuse Box in the engine compartment
Fuse Box Location
Fuse box diagram
2003-2004
2005-2007
Assignment of the fuses and relays in the engine compartment
| Name | Description |
|---|---|
| Fuses | |
| RT PARK | Passenger’s Side Taillamp Assembly, Front Sidemarker and Front Parking Lamp Assembly |
| HORN | Dual Horn Assembly |
| LT HI BEAM | Driver’s Side High-Beam Headlamp |
| LT LOW BEAM | Driver’s Side Low-Beam Headlamp |
| RT LOW BEAM | Passenger’s Side Low-Beam Headlamp |
| RT HI BEAM | Passenger’s Side High-Beam Headlamp |
| TOS | Manual Transmission Output Speed Sensor |
| SPARE | Not Used |
| THEFT | ECM (Electronic Control Module), TCM (Transmission Control Module), PASS-Key 111+ Module |
| LT PARK | Driver’s Side Taillamp Assembly, Front Sidemarker and Front Parking Lamp Assembly |
| LIC/DIMMING / DIMMING | Rear License Plate Assembly, Dash Integrated Module (DIM) |
| DIM/ALDL | DIM, ALDL (Assembly Line Data Link) |
| FLASHER | Turn Signal/Hazard Flasher Module |
| MANIFOLD | Manifold Flaps 1 and 2, Air Mass Meter, Canister Purge Valve |
| STRG CTLS | Steering Wheel Control Pad, Headlamp Switch |
| HTR VLV/ CLTCH | Heater Valve, Clutch Switch (Normal Closed), Clutch Switch (Normal Open), Jumper to Start Relay Coil for Automatic Transmission |
| WASH NOZ | Driver’s and Passenger’s Side Heated Washer Nozzles |
| PRE O2/CAM | Driver’s & Passenger’s Side Oxygen Sensors, CAM Phaser, Canister Purge |
| ECM | Electronic Control Module |
| TCM/IPC | TCM, ECM and IPC (Instrument Panel Cluster) |
| IGN MOD / IGN MOD/MAF | Front Bank Ignition Modules |
| ELEC PRNDL | Electronic PRNDL |
| TCC/ET | TCC/ET Brake Switch (Extended Travel), TCC/ET Brake Switch (Cruise Disable) |
| STOP LP SW | Stoplamp Switch |
| IGN SW | Ignition Switch (Power to IGN-3 and CRANK) |
| VOLT CHECK | DIM (Dash Integration Module) |
| ECM/TCM | TCM (Transmission Control Module), ECM (Electronic Control Module), IPC (Instrument Panel Cluster), PASS-Key 111+ Module |
| ODD INJ/COILS | Odd Ignition Coils, Fuel Injectors, Odd Injection Coils |
| WPR MOD | Windshield Wiper Module Assembly |
| INJ | Fuel Injectors |
| COMP CLUTCH | Compressor Clutch |
| WPR SW | Windshield WiperA/Vasher Switch |
| FOG LAMP | Fog Lamps |
| OUTLET | Center Console Accessory Power Outlet |
| POST O2 | Driver’s and Passenger’s Side Oxygen Sensors, LRPDB (Pusher Cooling Fan Relay) |
| I/P OUTLET | Instrument Panel Accessory Power Outlet |
| CCP | Climate Control |
| EVEN INJ/COILS | Even Injection Coils |
| PRE O2 | Driver’s and Passenger’s Side Oxygen Sensors, Transmission Output Speed Sensor |
| Circuit Breakers | |
| HDLP WASH C/B-OPT | Headlamp Washer Motor (Optional) |
| J-Case fuses | |
| R REAR | RRPDB (Passenger’s Side Rear Power Distribution Box) |
| R REAR | RRPDB (Passenger’s Side Rear Power Distribution Box) |
| L REAR | LRPDB (Driver’s Side Rear Power Distribution Box) |
| L REAR | LRPDB (Driver’s Side Rear Power Distribution Box) |
| HI FAN | High Cooling Fan Motor |
| LO FAN | Low Cooling Fan Motor |
| BLOWER | PWM Fan Motor Assembly |
| STARTER | Starter Solenoid |
| EBCM | Electronic Brake Control Module |
| ABS | Anti-Lock Brake System |
| Wiring Harnesses | |
| BODY W/H | Wiring Harness Connection |
| I/P W/H | Wiring Harness Connection |
| ENG W/H | Engine Wiring Harness Connection |
| FORWARD LAMP | Forward Lamp Wiring Harness Connection |
| Relays | |
| LO SPEED FAN RELAY MINI | Low Speed Fan Motor |
| HI SPEED FAN RELAY MINI | High Speed Fan Motor |
| ACCESSORY RELAY MINI | Accessory Power Outlets |
| S/ P FAN RELAY MINI | Series/Parallel Fan |
| PARK LAMP RELAY MICRO | Parking Lamps |
| HORN RELAY MICRO | Horn |
| HI BEAM RELAY MICRO | High-Beam Headlamps |
| DRL RELAY MICRO-OPT | Daytime Running Lamps |
| LO BEAM RELAY/HID MINI-OPT | Low-Beam HID Headlamps (Option) |
| HDLP WASH RELAY MINI-OPT | Headlamp Washer Motor (Option) |
| CIGAR RELAY MINI | Cigarette Lighter (Option) |
| BLOWER RELAY MINI | Front Blower |
| FOG LAMP RELAY MICRO | Fog Lamps |
| MAIN RELAY MICRO | Powertrain/ECM |
| STARTER RELAY MINI | Starter Solenoid |
| CMP CLU RELAY MICRO | Compressor Clutch |
| IGN-1 RELAY MICRO | Ignition Switch (ON) |
Passenger compartment
Fuse Box Location
Two fuse boxes are located under the rear seat.
To remove the rear seat cushion, do the following:
- Pull up on the front of the cushion to release the front hooks;
- Pull the cushion up and out toward the front of the vehicle;
- Slide the cushion out one of the rear doors and set it aside.
Fuse box diagram (Driver’s Side)
Assignment of the fuses and relays in the Rear Underseat Fuse Block (Driver’s Side)
| Name | Description |
|---|---|
| Fuses | |
| L FRT HTD SEAT MOD | Driver’s Heated Seat Module |
| MEM/ADAPT SEAT | Driver’s Power Seat Switch, Memory Seat Module |
| TRUNK DR RELEASE | Trunk Release Motor |
| REVERSE LAMP | ISRVM (Inside Rearview Mirror), License Plate Lamp Assembly |
| SPARE | Not Used |
| POSITION LAMP | Taillamp Assemblies, Front Position Lamp Assemblies |
| AUDIO | Radio, OnStar Module |
| REAR DR MOD | Rear Door Modules |
| BAS | Taillamps, Center High-Mounted Stoplamp, Flasher Module, ABS Module, Trailer Lamps |
| DRIVER DR MOD | Driver’s Door Module |
| HDLP LEVELING | Headlamp Leveling System Chassis Sensors (Export Only) |
| EBCM | EBCM (Electronic Brake Control Module) |
| CCP | CCP (Climate Control Panel) |
| IGN 3 | Heated Seat Modules, Air Inlet Motor, Shifter Assembly |
| J-case fuses | |
| AMP | Audio Amplifier |
| PUSHER FAN | Pusher Fan (Export Only) |
| Circuit Breakers | |
| SEAT C/B | Power Seat Switches, Memory Seat Module |
| Relays | |
| BAS RELAY MINI | Brake Apply Sensor |
| SPARE | Not Used |
| PUSHER FAN | Pusher Fan (Export Only) |
| L POSITION RELAY MICRO | Driver’s Side Position Lamp |
| R POSITION RELAY MICRO | Passenger’s Side Position Lamp |
| IGN 3 RELAY MICRO | Heated Seat Modules, Air Inlet Motor, Shifter Assembly |
| STANDING LAMP RLY MICRO | Control for Position Lamp Relays |
| TRK DR REL SOL RELAY MICRO | Trunk Release Motor |
| REV LAMP RELAY MICRO | ISRVM (Inside Rearview Mirror), License Plate Lamp Assembly |
Fuse box diagram (Passenger’s Side)
2003-2004
2005-2007
Assignment of the fuses and relays in the Rear Underseat Fuse Block (Passenger’s Side)
| Name | Description |
|---|---|
| Fuses | |
| TRUNK DIODE | Trunk Lamp |
| INTERIOR LAMP | Hush Panel Lamps, Puddle Lamps, Overhead Courtesy Lamp Assembly |
| PSGR DR MOD | Right Front Passenger Door Module |
| RIM | 2003-2004: RIM (Rear Integration Module), Ignition Switch, Key Lock Cylinder 2005-2007: ISRVM (Inside Rearview Mirror), Power Sounder, RIM |
| RIM/IGN SW | RIM (Rear Integration Module), Ignition Switch, Key Lock Cylinder |
| REAR FOG LAMP | Rear Fog Lamps (Export Only) |
| SPARE | Not Used |
| NAV | TV Tuner Assembly (Export Only), VICS (Vehicle Information Communication System) Module (Export Only) |
| AIR BAG | SDM (Sensing Diagnostic Module) |
| SPARE | Not Used |
| POWER SOUNDER | Power Sounder, Inclination Sensor |
| ABS | Anti-Lock Brake System |
| TRUNK LAMP | Trunk Lamp |
| FUEL PUMP MTR | Fuel Pump Motor |
| AFTERBOIL | Afterboil Heater Pump |
| R FRT HTD SEAT MOD | Passenger’s Side Heated Seat Module |
| SPARE | Not Used |
| SIR | SDM (Sensing Diagnostic Module) |
| RIM | ISRVM (Inside Rearview Mirror), Power Sounder, RIM, Passive Trunk Release Sensor |
| CANISTER VENT | Canister Vent Solenoid |
| SPARE | Not Used |
| Circuit Breakers | |
| DR MOD PWR C/B | Door Modules |
| J-Case fuses | |
| REAR DEFOG | Rear Window Defogger Element |
| SUNROOF MOD | Power Sunroof Module |
| Relays | |
| RAP RELAY MINI | Retained Accessory Power |
| SPARE | Not Used |
| REAR DEFOG RELAY MINI | Rear Window Defogger |
| SPARE | Not Used |
| AFTER BOIL MICRO | Afterboil Heater Pump |
| INT LAMP RELAY MICRO | Hush Panel Lamps, Puddle Lamps, Overhead Courtesy Lamp Assembly |
| IGN 1 RELAY MICRO | Ignition Switch |
| REAR FOG LAMP RLY MICRO | Rear Fog Lamps (Export Only) |
| FUEL PUMP MOTOR RLY MICRO | Fuel Pump Motor |
Conclusion
For owners and enthusiasts of classic Cadillac CTS 2003-2007, understanding the fuse box and relay systems is essential for vehicle maintenance. Regular inspection and maintenance of these components helped ensure the vehicle’s longevity and reliability, preserving its status as a symbol of Cadillac’s craftsmanship and innovation in the automotive industry during that era.
