Diagnostic Aids
WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
- Any data communication DTCs or related concerns must be corrected before diagnosing DTC P3051, P3053, or P3055.
- Only Replace a Component if the DTC resets during current drive cycle.
- The T19 Multifunction Power Supply Converter is not capable of setting DTCs. The K20 Engine Control Module sets DTCs on behalf of the T19 Multifunction Power Supply Converter. The K20 Engine Control Module and T19 Multifunction Power Supply Converter communicate on the powertrain CAN bus. If the K20 Engine Control Module loses communication with the T19 Multifunction Power Supply Converter for any reason, the K20 Engine Control Module will not be able to monitor the voltages of the T19 Multifunction Power Supply Converter. The K20 Engine Control Module interprets this as a loss of voltage and DTC P3051 and/or DTC P3055 may set as a result.
- If any of the DTCs P3051 thorough DTC P3056 are set inspect the T19 Multifunction Power Supply Converter connector for evidence of Corrosion or loose terminals and replace as necessary, if no terminal issues are found. apply a light coat of Dielectric grease to the terminals, clear DTC's and revaluate after performing 5 stop start events.
- If both DTC P3055 & DTC P3056 are set, the condition may be caused by an internally shorted starter, starter wiring circuits 6 and 4358 may be shorted together, or a lack of voltage on the T19 Multifunction Power Supply Converter Ignition Volage Terminal 6.
- If DTC P3055 is set, but DTC P3056 is not set the condition may be caused by an over-current event on the T19 Multifunction Power Supply Converter Regulated voltage output 1 Circuit 2172, that can cause the module to stop regulating voltage.
- If DTC P3055 is set, verify the ground connection for ground circuit 6151 and ground circuit 2550 are clean, tight, and in the correct location.
- Verify all components and control module powered by the T19 Multifunction Power Supply Converter circuit 2172 are operating properly.
- The T19 Multifunction Power Supply Converter B+ circuit 6340 terminal 11 supplies voltage to the T19 Multifunction Power Supply Converter control circuit 2172 Terminal 10.
- The last 2 digits of the circuit number are significant in identifying its power and ground functions.
- Circuits ending in 42 are primary fused B+ circuits (generally the first fuse in the circuit after the battery)
- Circuits ending in 40 are secondary fused circuits (generally fuses in a fuse block after the primary circuit)
- Circuits ending in 39 and 41 are ignition voltage circuits.
- Circuits ending in 50 are grounds.
- Circuits ending in 51 are low reference (ground) circuits.