Rear foglight not working MK1 Yaris

[Yaristotle]

The fuse can be inserted into its housing without problem. It only blows when the light is switched on.

I certainly do have a digi dash but the panel bulb itself has never blown. Indeed, when the new fuse was replaced but prior to inserting bulb in RFL the connection worked, showing the illuminated bulb on the panel and gave 12v on the multimeter at the RFL fitting. Only upon inserting the 21w buld into the light did the fuse blow.  

It has occurred to me that there could be an issue with the loom - perhaps the rear section. Never experienced this sort of thing before.

 

 

[stantheman1]

That sounds unlikely as you say you have 12 volts at the empty bulb holder. As a matter of interest, where exactly did you connect your multi-meter to read 12 volts?

[Yaristotle]

To the two 'sprung' electrodes that the bulbholder engages with when turned slightly clockwise to secure it in place.

[Derek.w]

Maybe it will blow the fuse without replacing the bulb suggesting a short on rhe wiring.

[stantheman1]

11 hours ago, Derek.w said:

Maybe it will blow the fuse without replacing the bulb suggesting a short on rhe wiring.

The fuse doesn't blow without the bulb in place as he wouldn't be able to confirm the voltage if it did.

[flash22]

It's a bad socket by the sounds of it

Remove the other bulbs from the rear light and test the fog light - all lamps share a ground - if that works it's the wiring on the rear light cluster its self

[bathtub tom]

14 hours ago, Yaristotle said:

To the two 'sprung' electrodes that the bulbholder engages with when turned slightly clockwise to secure it in place.

As a single filament bulb, I don't see why there should be two 'electrodes' in the bulb holder. Has the bulb a single contact on the base and could that be bridging the 'electrodes'?

[flash22]

31 minutes ago, bathtub tom said:

As a single filament bulb, I don't see why there should be two 'electrodes' in the bulb holder. Has the bulb a single contact on the base and could that be bridging the 'electrodes'?

the bulb holders have contacts you twist the holder in and the contacts line up with the terminals built in to the lamp housing

Later type p10 tail light

Bulb holder (brake light)

eg. https://www.ebay.co.uk/itm/321809676737

 

[Yaristotle]

Continue to be confounded further by the non-functioning foglight. Having replaced a new fuse I tried to setup a little rig whereby the bulb was connected to the backlight terminals via some cable clips. But upon turning the FL switch the RFL bulb did not illuminate and thus no 12v at the rearlight terminals. At lease yesterday, following Bob's enlightening info re the RFL having its own dedicated protection, I was getting the 12v at the socket. 

[flash22]

Because a circuit has voltage doesn't mean it can carry current, try using the 12V but pick up the ground from the body/exposed bolt

can you post pics of the plugs, holders and back of the light

[Yaristotle]

Please dismiss my last post as I must have been having some sort of aberration - I actually had NO fuse in said holder. GormRFL bulb to lless, or what?

Anyway I have currently got the RFL bulb to light when hardwired (as shown below). When I fix the bulb into place in the socket I now get nothing - which is obviously an improvement on blowing the fuse. I guess I will have to get the bulb fixed in place  as best as possible with wiring similar connected as photo, though, hardly an ideal solution..

[flash22]

See what you may have done - green croc clip grounded to the body ? try connecting green croc clip to the stud

the fault is on the rear light or the plug and socket

[Yaristotle]

1 hour ago, flash22 said:

See what you may have done - green croc clip grounded to the body ? try connecting green croc clip to the stud

 

See photo below (similar to what you are asking for) with the black lead to the terminal and the green lead to a suitable earthing point.

 

1 hour ago, flash22 said:

the fault is on the rear light or the plug and socket

It certainly is. Most expedient resolution would be to obtain replacement light - either new or one from the scrappers perhaps.

[flash22]

Pop the light off, there can't be much wrong if it's just the ground

see the above image of the light i posted for tom (bob)

As the indicator and tail/brake light works, it can only between the T-junction and the negative terminal

 

[flash22]

Silly question, you can't get these bulb folders 180 degrees out, can you ?

Can you post a pic of the bulb holder without the bulb in it

[Yaristotle]

Sorry, but do you mean bulb holders? 180? Excuse my ignorance.

Further to the point about the failed section are you saying that it is the area that I nave marked in green?

 

[flash22]

nope, just the top rail i arrowed, the bottom rail is 12v RFL

15 minutes ago, Yaristotle said:

Sorry, but do you mean bulb holders? 180? Excuse my ignorance.

 

lol my fat fingers, yes bulb holders, and they only go in one way, correct

 

[Yaristotle]

Voila:

[flash22]

Can you do one more test, I think I know the issue

put the fog light bulb and holder back in, but leave the indicator bulb out (holder not in the light) and see if the RFL works

[Yaristotle]

No, still no sign of light, sadly. Thanks for the idea, though.

[flash22]

Your indicator bulb holder has a broken tab and the negative is a bit crushed, swap it with the other side and see if the RFL works

[Yaristotle]

Can you just confirm whether you mean to actually remove the nearside rear light and connect it with the offside multi-plug? Presumably the offside RFL supply will then turn on the reversing light in this case which would confirm the offside rear light is defective...at least in part?

The reason that I need to check is that if both light units are removed I will require to replace the sealing gasket - at least I had to do this when I once removed the light unit previously. 

[flash22]

Just swap the indicator bulb holders (part that holds the bulb) nice and simple

[Yaristotle]

Swapped the indicator bulbholders but still no light from RFL.

 

[stantheman1]

20 hours ago, Yaristotle said:

Voila:

The bulb holder on the right is badly worn and needs replacing but can be fixed as a temporary measure by prying out the contact points so that a physical connection can be made.