The Door Mirrors on my XJS had not been working for sometime but did start working when I replaced the Fuse.

Though after using them only a couple of times, the fuse just blows again, for no apparent reason that I can think off and I have replaced that fuse quite a number of times.

Although I am using the correct fuse, I was wondering if I ought to try a heavier duty one?

Ideas guys

 

OB,

Don't put a higher rate fuse in there! The circuits are rated according to the expected load of the equipment. If you're blowing fuses, you have a problem with the mirror motors, the wiring or the connectors. Putting a bigger fuse in could mean that it won't blow at the expected overload and you'll get a heat buildup somewhere in the wiring circuit. Not good news!

Do the thorough thing and check the quality of connections at the switch, mirror wiring plug and both sides of the fuse terminals. You may have some corrosion buildup which means that more current is being drawn and blowing the fuse. With luck, you'll find the issue there and hope it isn't somewhere in the wiring loom.

Good luck

Paul

 

OB
PJTS' advice 100% spot on. The fuse rating should be 3A, though I think (subject to correction PJTS !) trying 5A could not hurt. The same fuse does the door locks too.

If a 5A blows, then finding the culprit can be a bit of a fiddle. First be SURE it is the mirrors. There is a common feed to the switch stalks and various separate wires to each mirror from there. The fault could be a short in the live feed TO the mirror FROM the switch, or in the mirror itself, or in the switch.

To do the test you have to isolate one mirror at a time, to do this you have two options: (i) remove the door cards and unplug the loom, or (ii) unscrew the mirror from the outside and with luck, you can pull out enough cable to unplug it from the loom, but put some string on the loom end to keep it from falling in the door!

So having isolated one of them, work the other and see if the fuse still blows. If yes, you have narrowed it down. If NO, reinstall the isolated one and isolate the other one and try again. Once you know which circuit is faulty the next thing is to find out if it is the mirror or the wiring.

One way to do this is to plug the mirror from the NON-fuse blowing side into the plug of the fuse blowing side, and work it again. If the fuse blows, you know it is the circuit, if it does not, you know it is the mirror !

Greg

 

Hi Paul

Thanks for replying but when Greg mentioned the door locks, its suddenly got me thinking!

So as you are on the same page, I'll reply to you both together.

 

Greg,

I'm sure you're right that a 5a fuse won't set the car on fire! And that's a neat description of isolating and testing the mirrors!

It's just a guess OB, but my money would be on corrosion in fuses, switches, wiring connections or earths, rather than motors. But that's just a guess!

Paul

 

Hi Greg

You've come up with something, that I didn't know.

I didn't know the 'door locks' both run off the Same fuse as the Mirrors!

But the Electric Door Locks don't work either and I have to lock each one up separately with a Key.

So maybe its the Door Locks that are Blowing the Fuse, instead of the Mirrors!

Do you think that this could be the problem.

Thanks Greg@PJTS

 

Hi Paul

Thanks but I think you mean 'Won't set the Car on fire AGAIN!'

re: (past stuck Caliper problem)

 

Ouch. Low blow. Lol

 

No it wasn't a Low blow at all!

Paul is always one of the first, to jump in and help me with sorting out problems like this.

'Greg in France' = 'Legend!'

 

OB
Could be. I suggest you test for it in this order:

5A fuse, and clip your test light to the 'downstream' side of the fuse holder, the other end to earth,

Work the mirrors, one at a time, and see if the fuse blows (ie the test light goes out)

Work the locks key in one side and then in the other, and see if it goes out. If it is the locks that do it, remove one side's front ankle panel and disconnect the loom plugs to one door. Then try the locks again, using the key in the door that is connected. If the fuse does NOT fail then test the other door the same way reconnecting the first tested door and using the key in this reconnected door. If the fuse fails when testing one or other of the doors, you know the short is in the door.

If the fuse fails whichever door is worked, you (probably) know the problem is in the loom before the doors !

Greg

 

Hi Greg

Thanks for showing me how to do the 'Test' I'm thinking that it could be the doors, because the 'Central Locking' isn't working and whatever locks the doors,

probably has more electrical resistance to overcome.

Than just a Couple of Mirrors.

So I put in a 'Fuse' adjust the Mirrors (everything is ok)

Then when I lock the doors with the 'Key' there may be some Mechanical Resistance to overcome, which then 'Blows the fuse'

Once that fuse has blown, it then takes out the Mirrors by default.

Maybe not one of the Best ideas that Jaguar ever had, as I would think that something like door locks could have done with a 'heavier fuse'

With this in mind, I'll do the Test as you suggest, before reporting back.

 

OB,

One of the reasons that the locks may not require a particularly high fuse is that the circuit is "just" passing current to a couple of solenoid / actuators which themselves are opening the locks which then push the rods back on the chrome levers. The current draw to the solenoids won't be massively high.

I'm with Greg on the theory that if it's a lock problem that is blowing the fuse, it will probably be somewhere before the solenoid. Even when the solenoids or lock rods get lazy they don't tend to blow the fuses.

A nice little job for the weekend, OB, and you won't get oily or wet!

Good luck

Paul

 

Hi Paul

Something else I didn't know!

But I've done a few tests and I have found, that its not the Mirrors, that are blowing the fuse.

The Mirrors will work all day long but as soon as you lock the doors it blows the fuse.

So it looks like the door Cards will have to come off or else get the Mirrors lined up then continue to lock each door with the key.

 

Dont forget the lock in the trunk lid.

 

That's an interesting thought!

Maybe the Trunk/Boot lock is the problem!

And the only one I haven't checked!