“But the lights work” is one of the things we hear most often on the phone. It feels logical: a battery that can run the dashboard ought to start the car. Very often it cannot, and the reason is simple.
Lights need a trickle, the starter needs a flood
Dashboard lights, the radio and the courtesy light use very little power. The starter motor needs an enormous amount for a few seconds to turn a cold engine over. A battery can have plenty for the first job and nowhere near enough for the second. That is how a car can light up as normal and then only click when you try it.
Watch the dashboard as you try to start it
- The lights dim sharply or go out: the battery is too weak. A jump start usually sorts it.
- Rapid clicking while the lights flicker: the same story, a low battery.
- One single clunk and the lights stay bright: the battery may be fine. It can be the starter motor or a poor connection, and a jump may not fix it.
- The engine turns at its usual speed but never fires: not the battery. Fuel, ignition or a sensor is more likely, and a jump start will not help.
- Nothing at all, with the lights staying bright: go through the simple checks below first.
Simple things worth checking
- Automatic gearbox: most will only start in P, and some in N. Push the selector firmly into P and try again.
- Push-button start: most cars want your foot on the brake, and a manual usually wants the clutch pressed right to the floor as well.
- Steering lock: if the key will not turn, move the steering wheel gently from side to side while you turn it.
- Keyless fob: a “key not detected” message can mean the fob battery is flat. Many cars let you hold the fob against the start button, or rest it in a marked spot, to start anyway. The handbook shows where.
Do not keep trying
Every attempt on a weak battery takes a bit more out of it. Two or three goes, a minute apart, is plenty. Past that, you can drain it so far that the alarm or the immobiliser starts to misbehave, and on some cars the starter motor gets hot. Switch off the lights, the fan and the radio, give it a minute, try once more, and then call.
A loose or crusty battery terminal
White or green crust on the terminals, or a clamp that moves when you push it, can stop the starter getting current while the lights still work. Do not go at it with tools or bare hands. When we arrive, we check the connections before anything else, because now and then a clean, tight clamp is the whole fix.
Hybrids and electric cars
On a hybrid or an electric car, lights that come on while the car refuses to go to ready usually point at the small 12V battery. Read jump starting an electric or hybrid car before you connect anything.
When to ring us
If the lights dim or the car clicks, a jump start is very likely the answer: €120 for the call-out, with no distance charge, anywhere we cover in Dublin, Meath and Wicklow. If it is the single clunk, or an engine that turns without firing, ring anyway and describe it. We will tell you honestly if we think a jump will not help, before anyone sets off.
Want to know what we do on the day? See our jump start service.
If the car has died somewhere busy, get everyone out and away from the traffic before you try anything else. Anyone hurt: ring 112 first.
Call 085 783 9202