My car's flashers does not work anymore. They started being inconsistent few days ago - but now are completely dead (except in rare cases where I manage to get 1 fast flash).

Using my basis knowledge, I suspect the relays (I've checked my fuses and they are fine).

I'm running off of time these days, so I thought I'd pay myself some luxury and bring the car at Honda - but they said they don't want to repair it as there is too many modified electronics (though all that was changed is the radio). If it can help to the diagnosis, my dash is also inconsistent (not the light - it just turns completely off), but I'm planning another question for that. All the lights works fine.

So I'm planning on diagnosing this during the week-end, but I thought it might be a good idea to get a list of possible causes if it happens that my relays are working properly.

What are the common causes for such problem? Any tips for the diagnosis?

2 Answers 2


If they work inconsistently, it may indicate bad electrical contact. In older cars the technique used for the on/of nature of flashers, is based on heat caused by current. If there's not enough current, due to too much resistance in the wiring, or in the switch, the flashers may continuously light, or not at all. Resisitance in the switch at your dash, or in the relay itself, or oxidated wiring may be the cause in that case.

When you use them and they do work, are they also more dim than usual, or just as strong? If the former, i'd suspect the relay, if the latter, i'd suspect the switch. I doubt it is a fuse though. Those things rarely cause bad contact. Only maybe if they're really really old. If you can reach it, try to spray some contact spray in the switch, and swap the relay with another one if you can. That way you can rule out the relay.

If the problem still persists, check if there's proper connection to the elctrical ground. Bad earthing is a common and often overlooked cause of electrical problems.

  • I did not notice any difference on the dim - so that would be the switch. If I understand well, both my flashers and dash are probably not working for the same reason ? Which "switch" are you refering at? Nov 3, 2016 at 20:19
  • 1
    I'm sorry i confused flashers with flashing your bright lights. It translates about the same in my language. Flashers, or blinkers, as i know them, are whole another thing. I'll update my answer.
    – Bart
    Nov 3, 2016 at 21:06
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    @Jean-FrançoisSavard with switch i referred to the lever that you use to control your flashers. The contacts you control with that lever are at the steering column. See if you can reach to it, so that you see the bare metal contacts and spray some contactspray or WD-40 on them. This dissolves oxidation, and may solve the problem.
    – Bart
    Nov 3, 2016 at 21:19

Common Issues -

Poor Grounds Moisture either in the bulb housing (causing a short) Moisture around the fuse box (or where ever the flasher relay is located) Incorrect bulb type/material (some older cars do not play well with new bulbs as the material used to make the connection in the socket is different)

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