Is it the ignition switch or starter?

When a car won't start, the culprit is typically either the ignition switch or the starter. If the engine cranks, the problem is usually not the starter; if there is no response at all, the ignition switch or its circuit is often involved. This article walks through how to tell which component is at fault and what to do next.

Ignition switch: role and common symptoms

What it does

The ignition switch controls power to the starter and to many of the car’s essential systems. Turning the key (or pressing the start button in modern cars) routes battery power through the switch to the starter relay and other circuits. In vehicles with push-button start, the switch is replaced by a start sensor, but the electrical role is the same.

Common symptoms indicating ignition switch problems

Look for signals that the switch or its wiring may be failing rather than the starter itself. The following are typical indicators:

• No electrical response when turning the key or pressing Start (no dash lights, no radio, no gauges).


• A key that sticks, feels loose in the column, or requires jiggling to get power to the accessories.


• Accessory functions (radio, lights) behave inconsistently or drop out when attempting to start.


• Security/immobilizer light staying on or flashing, suggesting an anti-theft issue rather than the starter.


• Intermittent starting behavior that seems to depend on the key position or wiring movement.

Diagnosing ignition switch problems involves checking for power at the switch, the ignition lock cylinder, and related wiring, and verifying that the anti-theft system isn’t preventing the engine from starting.

Starter motor: role and common symptoms

What it does

The starter motor is the engine’s starter: it engages the crankshaft with a solenoid and uses battery power to turn the engine over until combustion begins. The starter relies on a healthy electrical circuit, a good battery, and proper engagement from the ignition switch or start button.

Common symptoms indicating starter problems

Typical signs that point toward the starter rather than the ignition switch include:

• A single loud click or a series of quick clicks when turning the key or pushing Start, with little or no crank.


• The engine does not crank at all, even though the battery appears healthy and the lights are bright.


• The engine cranks slowly or labors to start, suggesting a weak battery, weak starter, or poor electrical connections.


• Starter motor or solenoid overheats after repeated attempts (requires cooldown).

If you observe these signs, the issue is more likely tied to the starter circuit, battery condition, or the solenoid rather than the ignition switch itself.

How to diagnose and differentiate: practical steps

Follow these steps to determine whether the ignition switch or the starter is at fault. Each step builds on the last to isolate the likely cause without unnecessary part replacement.

• Check the battery: verify a healthy voltage (about 12.6 volts with the engine off) and ensure the terminals are clean and tight.


• Inspect wiring and connections: look for loose, corroded, or damaged cables at the battery, starter, and relevant relays.


• Test for power at the starter relay: with the key in Start, confirm whether the relay is receiving battery voltage (and that the starter motor is getting current).


• Check the neutral/gear selector interlock: in automatic transmissions, try starting in Park and Neutral; in manual, depress the clutch to the floor.


• Listen for symptoms: if you hear a click but no crank, suspect the starter solenoid or high-current wiring; if there is no response at all from the ignition system, the ignition switch circuit may be involved.


• Consider the immobilizer/anti-theft system: if a security light is on or flashing, the system may prevent the engine from starting; consult your owner’s manual or dealer.


• For further confirmation, have a professional test the starter motor and related relays with specialized tools and test stands.

These steps help distinguish between ignition switch and starter issues. If you’re uncertain or uncomfortable with electrical work, seek professional help to avoid damaging wiring.

When to involve a professional

Because starting systems involve high current and safety-critical interlocks, consult a qualified mechanic if you cannot safely perform these checks or if the vehicle is under warranty. A technician can test the ignition switch, starter, battery, fuses, and immobilizer system with specialized equipment and diagnostic codes.

Summary

The ignition switch and the starter motor play different but connected roles in starting an engine. The ignition switch provides power to the starter and other systems, while the starter physically turns the engine over. By noting whether the car cranks, listens for clicks, or has electrical issues in the cockpit, and by methodically checking the battery, connections, and relays, you can distinguish between ignition switch and starter problems and decide whether a DIY check or professional diagnosis is appropriate.

Is the starter the same as the ignition switch?

No, the ignition switch and the starter are not the same thing; they are two different components that work together to start a car. The ignition switch is the electrical component, often on the steering column, that controls power to the car's electrical systems and sends a signal to the starter. The starter is a powerful electric motor under the hood that physically turns the engine to get it running. 
This video explains the function of a starter motor and ignition circuit: 59sDIY Potentials: Projects & IdeasYouTube · Jun 2, 2022
Ignition switch

• Function: The ignition switch acts as a central control for the car's electrical system. When you turn the key or push the start button, it sends power to the starter and other systems like the dashboard, radio, and fuel injection. 
• Location: Typically on the steering column, but can also be a push-button on the dashboard. 
• Problem indicators: If other electrical components like the radio or lights don't work when the key is turned to the "on" or "start" position, it could be a sign of a bad ignition switch. 

Starter

• Function: The starter is a motor that is responsible for cranking the engine. When the ignition switch sends a signal, the starter motor engages and spins the engine's flywheel, which in turn starts the combustion process. 
• Location: Under the hood, usually at the bottom of the engine near the transmission. 
• Problem indicators: If you hear a single click or a rapid clicking sound when trying to start the car, but the engine doesn't crank, the problem could be with the starter motor or the starter solenoid (a part of the starter system). 

How they work together

1. You turn the key to the "start" position. 
2. The ignition switch receives this signal and sends a low-current signal to the starter solenoid. 
3. The solenoid then uses a large electromagnet to complete the circuit from the battery to the starter motor. 
4. The starter motor receives power and begins to crank the engine. 
5. Once the engine starts, you release the key, and the ignition switch cuts power to the starter motor. 

How to tell if an ignition switch or starter is bad?

A bad ignition switch often prevents the key from turning or dashboard lights from coming on, while a bad starter usually causes a clicking noise or slow cranking even if the lights and radio work. If the engine cranks but won't start, it could be either, but if you can't turn the key or accessories don't power on, the ignition switch is the more likely culprit. 
This video explains how to test the starter, neutral safety switch, or ignition switch: 56sBleepinJeepYouTube · May 22, 2013
Ignition switch

• Key won't turn: This is a primary symptom. The key may be completely stuck or difficult to turn. 
• No power to dashboard: The instrument panel lights do not come on when you turn the key. 
• No power to accessories: The radio, wipers, or other electrical components don't work, or they may turn off randomly. 
• Engine stalls unexpectedly: The engine may start but then shut off after a few seconds, or stall while driving, because the switch is cutting power to the fuel pump or engine control unit. 

Starter

• Clicking noise: A single loud click when you turn the key can mean the starter solenoid is trying to engage but the starter motor isn't spinning. A series of rapid clicks can point to a weak battery, which is different but related. 
• Engine cranks slowly: The engine turns over slower than usual, which can indicate the starter is struggling. 
• Engine doesn't crank: The lights and radio work, but nothing happens when you turn the key, even though you hear a single click. 
• Whirring or grinding sound: The starter motor may make a high-pitched whirring or grinding sound, but the engine doesn't start, which can happen if the starter gear is not properly engaging the engine's flywheel. 

This video explains symptoms of a bad ignition switch, including difficulty starting the vehicle: 1mHonest Mechanic ColoradoYouTube · Apr 7, 2024
How to differentiate

• Check the lights and radio first: If they work fine when you turn the key, the problem is more likely the starter. If they don't come on at all, the problem is more likely the ignition switch.
• Listen for sounds: A clicking or grinding sound points to a starter issue, whereas silence when turning the key could be either but is a stronger indicator of a bad ignition switch if the lights are also out.
• Test the key: If the key is difficult to turn or won't turn at all, it's almost certainly the ignition switch. 

This video demonstrates how to test the ignition switch: 33s8020 AutomotiveYouTube · Jul 7, 2024

How to start a car with a bad ignition switch?

USE JUMPER CABLES

1. Open the car hood.
2. Locate the battery and ignition coil.
3. Use a jumper cable to connect the positive terminal of the battery to the coil's positive side.
4. Get a hold of the starter solenoid and connect it to the battery's positive terminal.
5. Remove the ignition wiring from the solenoid.

Will the starter click if the ignition switch is bad?

A clicking sound when turning the key, despite a good battery and starter, often indicates a faulty ignition switch or starter relay. First, test the starter relay by swapping it with a similar one if available. Inspect wiring connections at the ignition switch for corrosion or looseness.