Still Can't Trace Door Mirror Fuse Problem

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Lancsbob
Joined: Fri 15 Aug, 2014 17:35
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Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Mon 29 Feb, 2016 10:55

Fuse 24 still blowing which covers door mirrors & unfortunately heater
blower and its b****y cold.
Have stripped drivers door & wiring looks to be OK. What i want to
know is if i leave the mirror switch removed/unplugged does that isolate
the circuits to the 2 mirrors? which will save stripping the passenger door & checking it out.
Why i'm asking is that the fuse still blows
without the switch plugged in & am trying to narrow it down.
My next move will be to look at where the wiring passes from body
to door near the hinges to see if there is a break as in the boot lid problem.
Anyone have any experience of this problem?

Anyone know of a connection i can pull between the fuse box & the door?

Cheers Bob

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BladeRunner919
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by BladeRunner919 » Tue 01 Mar, 2016 08:01

If you leave the switch unplugged that does isolate everything from the switch to the actual mirrors. Under what circumstances does the fuse blow exactly?

Do you have a multimeter? If not, I'd suggest you get one as that will make fault finding a lot easier. They're not expensive - Screwfix have one for £7.99 at the moment.

Lancsbob
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Tue 01 Mar, 2016 19:07

If what you say is right then the fault is between the plug & the fusebox.
Trying to trace the route of the wiring is difficult, am working from door back to fusebox.
If i need to strip out footwell panels i will leave it untill warmer weather as
i have to do it in the open.
The fuse normally blows when i turn on ignition but sometimes it will last a couple of days then blow.
At the moment i'm driving round with the door panel off & switch unplugged, can't find any chafeing of wires inside door.
I swapped over a relay that works the heater blower, i noticed when i plugged in the fuse (with ignition on)the relay clicked.
Its worked all day OK but thats happened before. Will see how it goes, don't know if a relay can cause such a problem.
Yes i have a DVM but have limited knowledge of its use.

Cheers Bob

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BladeRunner919
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by BladeRunner919 » Tue 01 Mar, 2016 20:14

Are you sure it's not the heater that's the problem?

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Brian H
Joined: Tue 16 Dec, 2008 19:55
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  Z3 roadster 3.0i

Re: Still Can't Trace Door Mirror Fuse Problem

Post by Brian H » Tue 01 Mar, 2016 20:23

If your car has the winter pack on it, it will also have heated mirrors and heated washer jets, can you confirm if you have heated washer jets?

Can you confirm that it is not the blower motor that is taking out the fuse? i.e. replace the fuse then turn the blower on?

As Blades has said, if you leave the mirror switch off then this discounts the mirror motors and or heated mirrors as no voltage current will pass too them. I have know the switch loom the tucks in the handle to short out on the door handle retaining screw.

Edit: Blades beat me to it with the heater question!

Lancsbob
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Tue 01 Mar, 2016 22:20

Brian H wrote:If your car has the winter pack on it, it will also have heated mirrors and heated washer jets, can you confirm if you have heated washer jets?

Can you confirm that it is not the blower motor that is taking out the fuse? i.e. replace the fuse then turn the blower on?

As Blades has said, if you leave the mirror switch off then this discounts the mirror motors and or heated mirrors as no voltage current will pass too them. I have know the switch loom the tucks in the handle to short out on the door handle retaining screw.

Edit: Blades beat me to it with the heater question!
I asked the question earlier regarding heater & was told its almost certain to be mirror circuit.
Heater blower is covered by fuse 30. Blower works fine on all 4 settings when fuse 24 not blown.
Difficult to understand why blower stops when fuse 24 blows. I think someone earlier said it covers
the relay for the blower.
I disconnected the water jet heater but had no effect.
All is working at the moment allbeit with no trim on door.
Could there be a short inside the loom & not visible or does it have to short to bodywork?
Definately not shorting at screw as iv'e had loom hanging out of door with no switch attached & no bare wires in door at all.
Thanks for all your input if i find anything i'll let you know.

Cheers Bob

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BladeRunner919
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by BladeRunner919 » Wed 02 Mar, 2016 07:58

Just to rule the blowers out, can you remove the blower relay from inside the fuse box and then see if you still get the fuse blowing?

To answer your question about why the blowers depend on two fuses in order to work, relays need two power supplies - there's the main supply (provided by fuse 30) and that get's switched on and off by the relay. The actual 'switching' is carried out by a current that is supplied by fuse 24. So you need both fuses 24 and 30 to be operational otherwise you either get no switching (if fuse 24 is blown) or you are switching a dead circuit (if fuse 30 is blown - a bit like using a light switch during a power cut).

Lancsbob
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Wed 02 Mar, 2016 08:16

At the moment the fuse is not blowing & all is working, whether thats because iv'e
swapped the relay or that the wires are hanging loose as door is stipped i don't know.
Will put it all back together & see how it goes.
If it starts blowing again i will try without relay.

Cheers Bob

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pingu
Joined: Fri 30 Apr, 2004 17:01
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by pingu » Wed 02 Mar, 2016 19:13

As with ALL electrical problems, you need to let us know what year and model your car is.

Pre-facelift: Fuse 24 (10A) supplies the Jet Heater Thermoswitch and the Mirror Control Switch

Post-facelift: Fuse 24 (10A) supplies the Jet Heater Thermoswitch, the Mirror Control Switch and the Blower Relay

The Blower Relay is in the fusebox, closest to the bulkhead in the row of relays closest to the engine (the light green one behind the one I am pointing to)...

Image


Disconnect each in turn to isolate the fault.

You can use a dummy fuse to save on fuses. I have made one using a blown blade fuse with two wires soldered to the back of the blades. The wires can be joined together with a short length of household fusewire. You can also easily put an ammeter in the circuit instead of the fusewire.
Pingu

Lancsbob
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Thu 03 Mar, 2016 08:19

Thanks for that.
Its an 02 plate.
ATM iv'e swapped the rear relay with the front relay both light green & all is working.
Am using car very little in Winter so will have to wait a while to see how it goes.

Cheers Bob

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pingu
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by pingu » Thu 03 Mar, 2016 13:15

It could be the relay. Page 7100.0-09 shows most of the relays. If you swapped with the front relay (K2), does your horn work?

I suspect your washer jet heaters or thermoswitch.

The thermoswitch is permanently live when the engine is running.

http://www.porterbility.co.uk/Files/PDF/e36z3_01.pdf

Start at 0670.3-07. That is the page with Fuse 24 on it.
Pingu

Lancsbob
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Sat 05 Mar, 2016 17:39

pingu wrote:As with ALL electrical problems, you need to let us know what year and model your car is.

Pre-facelift: Fuse 24 (10A) supplies the Jet Heater Thermoswitch and the Mirror Control Switch

Post-facelift: Fuse 24 (10A) supplies the Jet Heater Thermoswitch, the Mirror Control Switch and the Blower Relay

The Blower Relay is in the fusebox, closest to the bulkhead in the row of relays closest to the engine (the light green one behind the one I am pointing to)...

Image


Disconnect each in turn to isolate the fault.

You can use a dummy fuse to save on fuses. I have made one using a blown blade fuse with two wires soldered to the back of the blades. The wires can be joined together with a short length of household fusewire. You can also easily put an ammeter in the circuit instead of the fusewire.


Went out today & fuse blew again so now i have removed the blower relay (do i need to remove fuse 30 also?) & will see if it still blows. ATM the mirror's are working.

I tried disconnecting washer heater at the connector under the bonnet a while back but it still blew.

Are the wing mirror heating wires on a separate circuit?

IF it proves to be the heater blower circuit what could be the cause? It seams to work perfectly when fuse isn't blown.

Can you explain how a DVM would help apart from proving i have a short which i already know. How does it show
there is a fault? :puzzle:

Cheers Bob

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pingu
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by pingu » Sat 05 Mar, 2016 22:08

Page 44 of the pdf shows you the circuit for Fuse 24.

Fuse 30 is Right High Beam
Pingu

Lancsbob
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Re: Still Can't Trace Door Mirror Fuse Problem

Post by Lancsbob » Sat 05 Mar, 2016 22:31

pingu wrote:Page 44 of the pdf shows you the circuit for Fuse 24.

Fuse 30 is Right High Beam
Oops i meant fuse 20 @ 30amp.

Will removing the relay isolate the blower or do i need to remove fuse also.

Can you think of any problems with blower that could blow fuse 24.
I thought it would only blow fuse 20 as 24 is to activate the relay.

Will run it for a while without relay & see what happens.

Cheers Bob

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