Heated Rear Screen/mirror Heaters Not Working

[johnan]

My turn to ask for assistance.

This morning is the first time I have needed the rear screen de-icer and mirror de-icers to work and they didn't!

According to the manual pressing the rear screen heater button should put both systems on for 15 minutes. (I have the IQ2 automatic heating and A/C option)The warning light comes on but nothing else.

I have checked the fuse no. 18 (heated mirrors) in the under bonnet fuse box and it looks OK, and the book says there should be a fuse in bay 20 controlling the rear screen but it is absent in my fuse box which is odd but obviously meant to be like that as there don't seem to be connectors in that fuse bay to take a fuse.

It is booked in for Friday but I would like to fix it myself before then if anyone has any good suggestions.

As it is not a fuse fault, I presume, I have my doubts as to whether they will have any idea of what to check next anyway.

I suppose a relay could have failed but will they know which and where?

[tarquin]

There is one thing to try but will need either a multi volt meter or a 12 bulb with 2 wire on it or a 12v tester from the likes of halford. ! am not sure which part of the de-fogger is not working. They are fed by two different fused circuits. The mirrors as you say fed by fuse 18 7.5A and Fuse 20 a 30A fuse feeds the heating element. If its the mirrors you are speaking of then I have not seen mine work that I can notice and is difficult to voltage measure without un-clipping the glass to get to it. If its the rear heater then you can first check the push on spade connectors where the cable connects to the element, then with the aid of either a multi meter or a 12v bulb on two wires check to see if there is any voltage reaching the element.If there is then the element is faulty, if there is no voltage I would check the 30 A fuse holder by pushing the fuse in and out a few times in case the pins have gone high resistance. Fuse 20 is not next to fuse 19 there is a gap then its after that.

Let me know how you get on

David

David

[johnan]

There is one thing to try but will need either a multi volt meter or a 12 bulb with 2 wire on it or a 12v tester from the likes of halford. ! am not sure which part of the de-fogger is not working. They are fed by two different fused circuits. The mirrors as you say fed by fuse 18 7.5A and Fuse 20 a 30A fuse feeds the heating element. If its the mirrors you are speaking of then I have not seen mine work that I can notice and is difficult to voltage measure without un-clipping the glass to get to it. If its the rear heater then you can first check the push on spade connectors where the cable connects to the element, then with the aid of either a multi meter or a 12v bulb on two wires check to see if there is any voltage reaching the element.If there is then the element is faulty, if there is no voltage I would check the 30 A fuse holder by pushing the fuse in and out a few times in case the pins have gone high resistance. Fuse 20 is not next to fuse 19 there is a gap then its after that.

Let me know how you get on

David

David

As ever David thank you for your very helpful advice.

I could tell neither the rear screen nor mirrors were heating up today as the screen and mirrors were both covered in ice after I had been for a 20 minute drive having switched the de-icer on before I left.(I scraped the rear screen before I set off so I could see out the back first.)

After fiddling a bit, I have one of those Maplin IR temperature guns, which I find quite useful, and I aimed it at the mirror surface and it was minus one degree after being on for about 5 minutes . So I reckon the heated mirrors, and screen, still ain't working.

I will have another prod around if it not too cold tomorrow.

One thing though, as I said before, in my manual it says that fuse 20 is for the heated rear screen and as you say there is a gap after fuse 19 before fuse 20......in actual fact in the car's fuse box fuse 18 and 19 are in position then there is a gap as in the manual, but then there is NO fuse in position 20. And I don't think there are receivers or prongs into which the fuse would fit either.There is a hole for a fuse however.

Perhaps my manual , probably earlier IQ, is not quite relevant to my car, later IQ, but in any event the mirrors are supposed to be fed from fuse 18 which IS in position and intact.So fuse 20 not being there wouldn't solve that one!

I will certainly keep you informed and I will do a bit of multi-metering and see what I find out.

John

[johnan]

Checked voltage on connectors on rear screen and reading was 0 volts, when switched on.

Tried a 30amp spare fuse in fuse position 20, which does have connectors (I was mistaken) and power but still no voltage at the screen. This fuse is missing in my fuse box but according to the manual should be there. This is the rear screen fuse.

Fuse 18 does not have any power to its connectors whether ignition is on or off or the demist button is on or off. This is the heated mirror fuse.

All very strange.

David, do you have a fuse in position 20 in your car in the under bonnet fuse box? I know the manual says there should be but mine has never had a fuse in that slot.

John

[johnan]

Sorry, duplicate post.

John

[tarquin]

Sorry john been out all day. Will check in the mornimg. The thimg is there has to be a fuse of large capacity i.e 30a due to the low resistance of the rear heater. I also have a laser temp sensor so will give you all the voltages and temp i have in the morning

David

[johnan]

Sorry john been out all day. Will check in the mornimg. The thimg is there has to be a fuse of large capacity i.e 30a due to the low resistance of the rear heater. I also have a laser temp sensor so will give you all the voltages and temp i have in the morning

David

That will be great David, thanks.

John

[Guest]

You'll be pleased to know, that having read this post yesterday, I decided to test my heated rear screen and I am pleased to say it works fine. I have not looked at the position of fuses however, it was way too cold for me to be outside. Hope you get your's sorted out soon, and at least Mr. T. should be able to discover the mystery of the missing 30amp fuse... or whill he?

[tarquin]

Hi John

well i braved the weather this morning. My wing mirrors started out at 7.4deg C and reached 38deg C in about 30 sec.After about 4min all the water formed on them had disappeared . The rear again started out at 7.4degC and increased to 25degC.

looking at it from the rear, the right hand side is 2degC hotter. The whole thing auto turned off and the indicator turned off after about 15mins. Looking in the fuse box in the engine bay, It is not easy to see which fuse is what in the numbering scheme. In the fuse box lid each fuse has written under it, its function. I have included a pic of mine showing the 3 fuses in question and all obviously have 12v on them. The weather is too bad to peruse taking them out to see which direction the supply is coming from and if indeed they have supply when the call for heat is off. will try later. from my understanding of the circuit all three have to be present. If you have no supply to either of these fuses then it is even more sinister.When I get a min I will look on the workshop manual to see if it has a useful flow chart. If the button on the A/C unit illuminates it suggests it accepted the command and data was sent to the ECU or sub module to activate that bus. Hope this helps til I can make more detail measurements.

P.S the fuses in question are vertical in the centre of the pic, not the one's at the top.

David

[johnan]

Thanks Bob for checking yours, if it is a "later" IQ I would be interested to know if your fuse box has the same fuses in it as David's.

David, thanks too for all your efforts, I am jealous of your system working as it should!

From your picture the difference in mine is that there is no fuse in the "20" position, 2 places below the two 7.5 amp ones.

I did try putting one of the spare 30 amp ones in there but it didn't help so maybe they have changed the wiring in some way for the later models.

I need to find out if all later IQs have that fuse missing by design, or is mine missing in error.

I will try to take a pic of mine later and fiddle a bit more.

I am really not keen on taking it in on Friday to have it come back with other things wrong, so to fix it myself is a priority if I can.

[johnan]

Here is a pic of my fuse box as it always has been. (No 30amp fuse below the 2, 7.5 amp ones)

Looking at your pic again David it appears that there is a gap of 2 fuse positions between the lower 7.5 and the 30 rather than the one position that the manual would suggest.

I'll go and have another look outside.

[johnan]

Further report:

Having spotted that the 30 amp defogger fuse in David's box is two places below the 7.5amp fuse and mine didn't have any 30 amp fuses in any of those positions, I took my spare 30 amp fuse and put it where David's picture indicated it should be.....Lo and behold all the defoggers, screen and mirrors, are now working.

This is surely not up to Toyota standards of quality control to leave fuses out of the fuse box?

Anyway I rang up MrT to say it is fixed and he has asked me to take the car in anyway to have it checked, but I have a feeling it is just so he can claim time off MrBigT as otherwise he will just have a cancelled booking and no income.

They can give me a spare, spare 30 amp fuse at least seeing I have used the one that came with the car.

Once again David thank you very much for going out of your way, and getting frostbite, to take a picture which made all the difference.

Good forum this!

John

[tarquin]

No problem mate. Like i said the user manual is a bit ambiguous. Look in the lid / cover of the fuse box it lists thw fuses, locations and purpose. Might help in the future

David

[Guest]

Johnan, here is the very difficult to take picture of the fuse box in question. I don't know how the hell Mr. T. thought it would be a good idea to put the damn thing in such close proximity to the Battery -where at least there is a gap- and the damn headlamp gubbins! Sheesh!

Okay, so the picture is a little out of focus even on the macro option -plus I shrunk it by 75%- but I was trying to hold back the cover and take the picture in the blind. I couldn't see what I was taking. Still, I managed to avoid any nipped fingers or other hand related skin. <_<

[tarquin]

Hi Bob

I am not sure we are looking at the same area. The fuses in question are to the left of 2 blue relays

David

[johnan]

Johnan, here is the very difficult to take picture of the fuse box in question. I don't know how the hell Mr. T. thought it would be a good idea to put the damn thing in such close proximity to the battery -where at least there is a gap- and the damn headlamp gubbins! Sheesh!

Okay, so the picture is a little out of focus even on the macro option -plus I shrunk it by 75%- but I was trying to hold back the cover and take the picture in the blind. I couldn't see what I was taking. Still, I managed to avoid any nipped fingers or other hand related skin. <_<

Thanks for the pic Bob, but as David says it doesn't quite cover the area in question which is below the two 7.5 amp fuses in the line of slots runnning towards the front of the car.

I went up to MrT this morning and asked to have a look at the latest IQ in the showroom to check it's fuse box and confirmed that the fuse in mine was missing on delivery.

Much soul searching and buck-passing ensued with the service manager being suddenly unobtainably away on a test drive (though he was there when I arrived) and paper work produced to show a PDI had been done but no-one knew by whom.

I cancelled my appoinment for Friday and they gave me a replacement fuse for the spare I had to use, so all is well and maybe someone will be more careful in future.

John

[tarquin]

John

Its the same everywhere, As I I have said and ranted about on here. NO ONE in these company's will take responsibility. I recently had a run-in you may recall regarding not being able to fit a xmas present of the lower garnish because my iQ and Toyota badges were fitted too low to the edge. What ensued was a complete joke. With them moving the badges half way up the door and fitting the garnish nearly 1/2 inch from the lip. Answer from them "Sorry sir, we don't have a template for fitting them" No but you do have 3 of them on the forecourt you could have taken a ruler to. Total incompetence. There is even an on-line installation guide which I left with them.

David

[johnan]

John

Its the same everywhere, As I I have said and ranted about on here. NO ONE in these company's will take responsibility. I recently had a run-in you may recall regarding not being able to fit a xmas present of the lower garnish because my iQ and Toyota badges were fitted too low to the edge. What ensued was a complete joke. With them moving the badges half way up the door and fitting the garnish nearly 1/2 inch from the lip. Answer from them "Sorry sir, we don't have a template for fitting them" No but you do have 3 of them on the forecourt you could have taken a ruler to. Total incompetence. There is even an on-line installation guide which I left with them.

David

That is just so inept, how can anyone be so stupid?

Did they have to "steam off" the misplaced trim and lettering and try again?

I have sent a communication to Mr BigT Customer Services describing what has gone on.It will be interesting to find out their take on it.

John

[tarquin]

They claimed they ordered new badges in but i know the guys in the spares dept. Who said they have NEVER orfered those parts in. So my guess is they heat gunned them off. Be interesting to see what MR T say. Was your car new when you bought it?

David

[johnan]

They claimed they ordered new badges in but i know the guys in the spares dept. Who said they have NEVER orfered those parts in. So my guess is they heat gunned them off. Be interesting to see what MR T say. Was your car new when you bought it?

David

Yes, I loved my previous IQ so decided to buy the updated version before the 3 year warranty ran out on the first one, and I find the newer one so much improved in subtle ways over the original (still dim dome light though!).

I ordered it in February last year and got it in August.

The wait was due to the colour (red) and spec that I wanted, and the awful Tsunami.

Just got an e-mail from MrBigT saying they have passed my information to head office Customer Relations, who will be in contact very shortly.

We shall see what they have to say.

John

[tarquin]

If they send you chocolates, their mine lol

PM me and I will be able to do you a very good deal on a dome light swap out

David

[johnan]

If they send you chocolates, their mine lol

PM me and I will be able to do you a very good deal on a dome light swap out

David

As long as I can keep the caramels!

A good result would be a shot across the bows of the local service manager who frankly is a bit of a glib chancer and needs a reality check.

I have followed developement of the Tarquin Innovations interior light upgrade with interest, but I have never used the current (no pun intended) one as I tend not to use the car when it is dark, otherwise I would ask you for one straight away.

Keep me informed of any new TI inventions!

John

[tarquin]

No problem John. I know what you mean about not using the car at night. Noticed something strange this morning. Early about 7am tipping it down this morning. The headlights were like i didnt have them on. Then i noticed looking out the RHS lamp was kinda being diverted to the left and was lighting up the fence on the motorway just like beam mis alignment. So not much forward light. Checked them out later and they are fine. Very odd. Can i interest you in a round thing with a hole in the middle

David

David

[johnan]

No problem John. I know what you mean about not using the car at night. Noticed something strange this morning. Early about 7am tipping it down this morning. The headlights were like i didnt have them on. Then i noticed looking out the RHS lamp was kinda being diverted to the left and was lighting up the fence on the motorway just like beam mis alignment. So not much forward light. Checked them out later and they are fine. Very odd. Can i interest you in a round thing with a hole in the middle

David

David

A loo seat?

Or a Polo mint?

Is it possible that rain droplets on the light's outer surface could form a kind of secondary lens which could distort the beam direction?Doubt it, but you never know!

John

[tarquin]

It is weird. You can actually see the beam point to the kerb and there is more light to the left than in front. In dry conditions its straight , not brilliant but normal. Maybe a lens issue thats been missed. Have PM'd you

David