Odd Bulb Issue...

[Toms306]

Ok, this is for the Focus, basically the reverse light doesn't work.

I've tested the bulb - it has continuity and about 0.5 Ohm resistance.

I've tested the bulb holder - it gets 12 volts in reverse with ignition on.

Yet the bulb doesn't light up in the holder, wtf is going on there??

Tom

[1616six]

Could still be a knackered bulb, have you tried changing it?

If it's not the bulb, take it back, it's under warranty..

[vincent1]

yes as above change the bulb for a new one as maybe going open circuit under load failing that go back under warranty at least you can then say you have swopped the bulb for a new one.

[Toms306]

Not worth the hassle taking back for a bulb lol. Not tried changing the bulb yet, but if theres continuity through it I don't see why it wouldn't work?

[Eeyore]

wrong way round? put in a new bulb?

[1616six]

Not worth the hassle taking back for a bulb lol. Not tried changing the bulb yet, but if theres continuity through it I don't see why it wouldn't work?

Somehow, bulbs can still show continuity when they're 'half blown' so to speak, I've had car and household bulbs even where the filament looks perfectly fine but it's knackered.

Sam, the bulbs fit one way.

[Toms306]

Ah ok, fair enough then. Will see if I've got another to fit, still got rear lights from 306s and Golfs....whats the betting they use a different size though lol.

[Toms306]

Tried a new bulb, no difference.

Seen there could be corrosion between the bulb holder and plug though from googling. Will check tomorrow but its all pretty clean outside so I cant imagine that'll be the issue.

[Niall]

Don't forget Tom bulbs do also rely on the gas inside them to light. No gas, no light. That said if you have tried a new bulb and still nothing, you sure the bulb is making proper contact in the holder? No bent pins etc?

[Toms306]

That's true, hadn't thought of that! But yeah, brand new bulb as I was passing Halfords and made no difference.

The bottom pin is still very springy so I'm sure that's making contact. Side one looks ok as well.

[vincent1]

my next check would be too have ignition on and in reverse with new bulb in holder with multimeter if you can check on the back of bulb holder if possible the voltage on the wires if you can get to anything metal to place probes on im just wondering if the voltage disapears with a good bulb in there maybe a wiring issue if it does

[Toms306]

Turns out it was the switch. First proved by the lack of automatic rear wiper when reversing. Then proved by bypassing the switch with a jumper wire.

The 12 volts I was reading was actually 12 millivolts...I'll put my spec's on next time, silly small screen.

[Piggy]

Haha

Other thing I was guna say was check the earth. But simple enough fix being the switch.

How much is a switch then? Bet its a pig to get at

[Toms306]

It's a complete arse to get at in all honesty, I don't know how I'm gonna get a socket down there! Was bad enough getting a hand there to unplug it lol, and I'm not removing the battery to lose all the settings lol.

Brand new switch is only about a tenner I think so not too bad but there are a few types so not sure which it is yet.

[Grant]

If you're that hell bent on not losing your settings (will probably be quicker to re set everything and gain access to the switch) then why not use jump leads on the battery to keep the power and remove it.

[Toms306]

Hmm, that's not a bad idea tbh!

I've changed quite a few settings in the various modules so would take a while to change them all back if I did lose them (they may not revert back to factory though, not sure). But then theres radio settings and the ECU would have to relearn my driving etc...think it'll be easier not to lose all that lol.

Looks like I may have bigger issues to look into first though.

[Piggy]

If you're that hell bent on not losing your settings (will probably be quicker to re set everything and gain access to the switch) then why not use jump leads on the battery to keep the power and remove it.

This is a top tip.

Did this all the time at the garage when people didnt have radio codes etc

[Niall]

Tom generally modern cars don't revert back to standard when the battery is removed. I know with the kia i just loose radio station text (the frequencies are still stored) and they come back as soon as you scroll through the stations. All other settings remain.

[daddyfixit]

as long as the radio is turned off and keys are out of the ignition you wont lose the code......but if its an older ford radio and you do lose the code then pm me .

[Toms306]

Keys have to be out to open the bonnet anyway, but I didn't realise that....surely that's a bit pointless as if someones gonna nick the stereo they're not likely to do it with the keys in and turned on?

And thanks for the offer but I already have a Ford radio code source. I do have the handbook pack though, so the radio code should be in there hopefully.

Niall, now you mention it, I don't remember losing any settings on the 206 when changing batteries on that. Though there was a weird 'soft reset' to do so as not to scare the BSI lol, not sure if Fords are the same, will have to look into that.

[Connor]