can a bad interlock cable make the car not start

[DiEliana]

Yes, a faulty interlock cable can absolutely prevent your car from starting. This cable is a critical safety component, often connecting the transmission shifter or clutch pedal to the ignition system. Its primary role is to ensure the car is in "Park" (for automatics) or the clutch is fully depressed (for manuals) before the starter motor can engage. If the cable snaps, becomes stretched, or the switch it activates fails, the car's computer receives no signal, effectively blocking the starting circuit. It's a classic case of the vehicle's safety system working as intended to prevent an accidental lurch forward, but leaving you stranded.

Diagnosing this issue involves a few steps. First, try moving the gear shifter firmly into Park and then back to Neutral to see if it starts. Sometimes, a misaligned cable can be temporarily jiggled into working. For a manual transmission, check if the clutch pedal feels different or has excessive free play. A more definitive test involves locating the neutral safety switch (typically on the transmission or shifter assembly) and checking for voltage with a multimeter. If power is present on one side of the switch but not the other when the key is turned, the switch or its cable linkage is the culprit. Replacing the cable or switch is generally a straightforward repair, but accessing the component can sometimes be labor-intensive. It's important to note that a no-start condition can also be caused by a dead battery, a faulty starter motor, or a bad ignition switch.

Common Symptom	Likely Problem Area	Quick Check
Car starts in Neutral but not in Park	Misadjusted or failing interlock cable/switch on automatic transmission	Firmly cycle the shifter through all gears.
No crank at all, brake pedal feels stiff (automatic)	Brake-transmission shift interlock (BTSI) cable or switch failure	Ensure brake pedal is depressed fully.
Clutch pedal feels loose or has no resistance	Broken clutch interlock cable or failed switch	Visually inspect the cable connection at the top of the pedal.
Dashboard lights illuminate but no engine crank	Faulty neutral safety switch or its wiring	Test switch with a multimeter for continuity.
Intermittent no-start condition	Stretched cable or failing switch	Issue may come and go depending on pedal/shifter position.

[LaMiguel]

Oh, for sure. My old truck had that exact problem. I'd turn the key and get nothing—just a click. After replacing the battery and starter for no reason, a mechanic friend figured it out. The little cable from the clutch pedal had snapped. He rigged up a temporary bypass switch under the dash just so I could get to work. It’s one of those cheap parts that can cause a huge headache.

[VanNevaeh]

As a mechanic, I see this often. The interlock is a simple safety device. If its cable breaks or the switch malfunctions, the vehicle's computer is essentially told the car is in gear, so it disables the starter circuit. The repair isn't usually complex, but diagnosis is key. We first rule out the battery and starter, then check for voltage at the safety switch. It's a common and often overlooked cause of a no-start.