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2017 Cadillac CT6 No-Start Issue - Cranks but Won't Catch

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Sarah K. · rep 0 · May 22, 3:56 AM · 1 replies · solved · Question

Vehicle: 2017 Cadillac CT6 Luxury

Hello Cadillac community,

I'm having a major problem with my 2017 Cadillac CT6 Luxury (3.6L V6). This morning, I went to start it, and it just cranks and cranks but won't actually turn over and start. It sounds like it's trying, but it never catches.

I checked the battery, and it seems fine – lights are bright, radio works, and it cranks strongly. I tried both key fobs, thinking it might be a security issue, but no luck. There are no warning lights on the dash other than the usual ones that come on when the ignition is just on.

Has anyone experienced a similar no-start condition with their CT6? What should I be looking for? Could it be a fuel pump, ignition, or something else entirely? Any advice would be greatly appreciated as I'm stranded!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:56 AM

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ClearTheCode admin answer:

A 'crank but no start' condition on your 2017 Cadillac CT6 can be frustrating and points to a fundamental issue with one of the three elements required for an engine to run: fuel, spark, or air (compression). Since it's cranking strongly, we can likely rule out a completely dead battery, but other electrical components could be at fault.

Here are the most common causes and diagnostic steps:

  1. Fuel Delivery Issues:
    • Fuel Pump: The fuel pump might not be sending fuel to the engine. Listen for a faint whirring sound from the rear of the car for a few seconds when you first turn the ignition to the 'on' position (before cranking). If you don't hear it, the pump might be failing or its relay/fuse is bad.
    • Fuel Filter: A severely clogged fuel filter can restrict fuel flow.
    • Fuel Pressure Regulator: A faulty regulator can prevent proper fuel pressure.
  2. Ignition System Problems:
    • Spark Plugs/Coils: While less likely to cause a complete no-start across all cylinders suddenly, a widespread failure of ignition coils or spark plugs could prevent ignition.
    • Crankshaft Position Sensor: This sensor tells the engine control module (ECM) when to fire the spark plugs and injectors. If it's faulty, the ECM won't know when to initiate the combustion process.
  3. Security System (Immobilizer):
    • Even though you tried both fobs, a fault in the vehicle's immobilizer system could prevent the engine from starting. Look for a security light or message on the dash that might indicate this.
  4. Engine Control Module (ECM) or Wiring:
    • A rare but possible cause is a faulty ECM or damaged wiring to critical sensors.

What to do:

  • Check Fuses: Consult your owner's manual for the location of the fuel pump fuse and relay, as well as any relevant ignition system fuses. Check them for continuity.
  • Listen for Fuel Pump: As mentioned, listen for the fuel pump prime when turning the key.
  • Check for Codes: Even if no dash lights are on, a pending or stored code might exist. A professional scan tool can often retrieve more specific diagnostic trouble codes (DTCs) related to starting issues.

When to see a shop:

Given the complexity of modern vehicle systems, if basic fuse checks and listening for the fuel pump don't reveal an obvious cause, it's highly recommended to have your CT6 towed to a qualified mechanic or Cadillac dealership. They have specialized diagnostic tools to check fuel pressure, spark, and sensor readings, which are crucial for accurately pinpointing the problem.

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