Rear foglight not working MK1 Yaris

[Yaristotle]

Hi all

I am not sure if I am hijacking the thread here but, if so, I will restart anew. The links provided have given some cause for concern regarding my own electrical issues.

The car is a Yaris Mk1 2004 1.3 Colour Collection (I never did know what that meant), which has just hit a rather meagre 40k. Everything works fine on he vehicle with one exception: the rear foglight. I have tried several bulbs and a couple of different bulb holders but the light remains dead. So I started thinking that there was perhaps a problem with the light switch, which is sited on the indicator stalk – the rear foglight requires four separate items to be switched on: 1. sidelights, 2. headlights, 3. front foglights and then 4. rear foglight.

I have removed the upper and lower shroud to obtain access and, in conjunction with the leccy diagrams from Mr Haynes and an screwdriver tester, tried to determine what cable is supplying which component. From doing this I thought I might be able to conclude whether the switch had failed. Generally I find the Haynes diags pretty perplexing as they appear to show the layout re logical connections rather than physical. What would be useful for me would be a diagram (better than photo) of the said stalk depicting each connecting cable and its component.

But the problem is confounded further. My 2004 model is slightly different from the earlier models in that they were fitted with a few supplementary items like the front FLs and a couple of minor internal trinkets. (The front Fls did not seem to be an available option on the Yaris prior to 2004 so are not shown on any of the Haynes diagrams). As a result, the cabling has changed in certain areas increasing the difficulty in following the diagrams.

One thing I have not checked are the fuses. I avoided this because the Haynes shows the said fuse as protecting side, tail & number plate light, rear foglight & switch illumination. As the other items operate correctly the fuse did not present an issue. To complcate matters further though the Haynes also shows.

I thought initially that the fuse location diagram provided by Flash22 initially looked to add a little clarity to the matter. Yet even this shows the front FL as protected by fuse no 4 (7.5amps) plus other circuits and also shown as covered by fuse no 8 (15amps). Maybe there are alternate specs for different markets?

I would greatly appreciate any advice from anybody re the non-functioning foglight.

[FROSTYBALLS]

Split into new topic.

[flash22]

rear fog light, do you have multimeter ?

rear fog light - headlights or side lights on, turn the rear fog on

Does the fog light symbol come up on the dash ?

are the fog lights on the stalk or a button on the dash ?

[Yaristotle]

6 minutes ago, flash22 said:

rear fog light, do you have multimeter ?  Yes...and have used it.

rear fog light - headlights or side lights on, turn the rear fog on? Side and heads have to be on for the fog light to work.

Does the fog light symbol come up on the dash ? No. But it did when working previously.

are the fog lights on the stalk or a button on the dash ? Stalk.

 

[flash22]

ok i will look up the oem diagrams

 

[Cyker]

Colour Collection was just the trim name, like e.g. T-Spirit or Design.

As the name suggests, its main draw was a massive selection of colours compared to the handful available on the normal trims.

I remember one of the previous mods had one in a specific blue and was obsessed with it  At least until she changed to... an Aygo IIRC?

[flash22]

Check the B-ecu fuse 7.5 amp and/or the fog light relay

Oh, dear cyker 😉 only if there was a random website with the colour collection info on it.........................

http://cyker.net/Public/CarStuff/Yaris-Colour-Collection-February-2005.pdf

 

[Cyker]

 

Edit: Oh that's weird, it seems to be corrupted...!

[Derek.w]

The reversing light  is a seperate fuse but its marked up as gauge fuse in passanger compartment fuse box.

Note Power from ignition switch.

[flash22]

12 hours ago, Derek.w said:

The reversing light  is a seperate fuse but its marked up as gauge fuse in passanger compartment fuse box.

Note Power from ignition switch.

Do you have the wiring diagrams ?, the fog light uses multiple fuses you have a relay, main power and control side

No light on the dash either

[Yaristotle]

20 hours ago, flash22 said:

Check the B-ecu fuse 7.5 amp and/or the fog light relay.

 

You are absolutely correct, it is indeed the ecu-b fuse (7.5 amp). Upon removing it I could clearly see that it had blown. So I fitted another 7.5 amp fuse from the engine compartment. I will obviously need to obtain a replacement. Annoyingly the Haynes does not show a 7.5 amp fuse in its engine compartment fusebox so I need to promptly find out what items this protects.

Unfortunately the replacement fuse has blown also, so I suspect I have an issue with the switch or perhaps the wiring. One thing I did notice, though, was that when the replacement fuse was fitted the rear foglight symbol on the instrument gauge came on and the multimeter showed that there was 12v available at the fitting, so good news there.

Oh yes, and they are only 21w bulbs that I am trying. All rather annoying, really, as the MOT is imminent. 😔

 

[stantheman1]

I would try a different 21 watt bulb and since you have a multimeter compare both for resistance making sure you don't mix them up as the one blowing fuses could be faulty internally(not unheard of).

[Derek.w]

My diagram is not specific for Colour Collection but it falls unto the Year category for Yaris.

 

[Yaristotle]

1 hour ago, stantheman1 said:

I would try a different 21 watt bulb and since you have a multimeter compare both for resistance making sure you don't mix them up as the one blowing fuses could be faulty internally(not unheard of).

Good move. Tried this and found the existing bulb had a 2 ohms res and another had 2.4 ohms. Was expecting a shade below 7 ohms. Should this raise alarm bells? These bulbs are part of a batch of Lucas (P o D) obtained from the bay. 🤔

[flash22]

21w/12v = 1.75a

21w/1.75a = 6.8 ohms

 

2 ohm - 5w ??

It should be a single element bulb 382 P21W

I will have a look at the diagrams again but im not at that machine atm

 

Anything else on the car not working ??

 

[Yaristotle]

Well the next step is to remove the 7.5 amp fuse (passenger fusebox) which covers the OBD circuit and pop this into the engine fusebox removed earlier - still not sure what it protects. I will be heading to our Toyota dealers tomorrow to obtain some replacement fuses and will also get a couple of 21w bulbs (382 as recommended) - hopefully a better bet than the Lucas. Thanks greatly for all the suggestions and any further advice. 👍

[flash22]

Toyota dealer for fuses and a bulb, are you feeling rich

Halfrauds will be cheaper, or even ECP if you have one nearby

[bathtub tom]

3 hours ago, Yaristotle said:

found the existing bulb had a 2 ohms res and another had 2.4 ohms. Was expecting a shade below 7 ohms. Should this raise alarm bells?

It wouldn't bother me, as the resistance would rise as the element heats up and unless you measure the current with the bulb working, it's onlytesting if the filament's intact.

[Yaristotle]

2 hours ago, flash22 said:

Toyota dealer for fuses and a bulb, are you feeling rich

Halfrauds will be cheaper, or even ECP if you have one nearby

Both of those are within reach but will either do the same type of spade fuse as Toyota?

8 minutes ago, bathtub tom said:

It wouldn't bother me, as the resistance would rise as the element heats up and unless you measure the current with the bulb working, it's onlytesting if the filament's intact.

Good thinking. Thanks for this.

[flash22]

Most places carry the fuses, often called the wrong name - Micro - They are actually called Low Profile Mini or LP Mini

 

 

[Yaristotle]

Actually, I went with your recommendation and headed to Halfrauds. They did, indeed, stock the Toyota type flat-blade fuse so I picked a small bag of 7.5 amp jobs. The link you provided showing the fuses/relays details appears substantially more relevant than the Haynes versions (which I have relied on previously) though not completely accurate. For instance re Fuse no 7: ECU-B - Headlight, Rear fog light - headlights are protected by a different circuit - this is the fuse that has been blowing. Also I do not believe that there is a front fog light relay as shown in the diagram though this matters not as the FFLs are fine. Also I could not see any sign of a circuit/fuse re the reversing light but , again, this poses no practical issue.

What I intend to do next is set up a rear fog light circuit of my own using a switch separate from the existing control but still wired into the prevailing cables. Presumably this would require a switched live supply via the headlight circuit? Additionally, the switch would need a panel light supply. I will need, then, an inline fuse rather than using the existing arrangement - could not see anything like this available earlier. Any probs with this idea? Thanks again for any thoughts. 🙂

[stantheman1]

Try a bulb from a different batch or use one from the indicators before delving too deep.

[Yaristotle]

13 minutes ago, stantheman1 said:

Try a bulb from a different batch or use one from the indicators before delving too deep.

I will try this. Might also try said bulb in the indicator. Thanks.

[flash22]

Replace the switch ? Sounds like a dead short somewhere if it blows the fuse immediately if it only does it after moving the switch that could be of the loom to the rear/rear light connector

do a resistance check using the body ground and output side of the fuse (fuse removed)

[flash22]

Hay

Just a thought, do you have the Digi dash ? Have you checked the bulb if that bulb has blown it may have blown dead short, that would put a dead short on the switch