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Author: Subject: Oh c**k!
speedyxjs

posted on 27/12/09 at 12:45 PM Reply With Quote
Oh c**k!

So much for finishing the wiring today, iv fried the electrics

I was wiring the brake warning using a relay (due to this).

I unscrewed the cap to make sure the light came on, it did but when i put the cap back on, the light didnt go out. If i unplugged the relay and put it back in again, the light was off so i decided the problem must be that i needed something connected to the 5th pin so (stupidly) i connected it straight to ground.

Switched the ignition on and have fried all the ignition wires

Im off to look for a new steering column

Any idea's why it has fried?

[Edited on 27-12-09 by speedyxjs]

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speedyxjs

posted on 27/12/09 at 01:07 PM Reply With Quote
This is how i have wired the relay:





How long can i resist the temptation to drop a V8 in?

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meany

posted on 27/12/09 at 06:42 PM Reply With Quote
this maybe of help.
scroll down to "The Famous Bosch Relay".

http://www.bcae1.com/relays.htm

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dinosaurjuice

posted on 27/12/09 at 07:40 PM Reply With Quote
quote:
Originally posted by speedyxjs

Any idea's why it has fried?

[Edited on 27-12-09 by speedyxjs]


was it fused?

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Dave Bailey

posted on 27/12/09 at 10:19 PM Reply With Quote
Sorry but I thought that the brake warning lights illuminte by switching to gnd... either through:-

Hand Brake switch
Brake Fluid switch
Test Switch.

These should all normally open...

Is this not how things work? All should be fused to protect the wiring.....

Dave B

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SteveWalker

posted on 27/12/09 at 11:53 PM Reply With Quote
Dave's right. The handbrake light is fed from the switched live from the ignition switch, via a fuse, to the bulb and the negative side of the bulb is grounded by the handbrake/fluid level/test switches when they operate.
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iank

posted on 28/12/09 at 04:41 PM Reply With Quote
I agree with Dave and Steve. Flak posted a diagram on the other thread about how it is normally wired. I've never seen a relay be required, and it's not ideal as these things are designed to fail safe and a relay adds a failure mode.

Maybe this diagram will help.

Description
Description






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Anonymous

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David Jenkins

posted on 28/12/09 at 04:50 PM Reply With Quote
^^^^^^

That's how mine is wired... except the 'test switch' is attached to my handbrake. Handbrake on, or low fluid, lights the lamp.






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iank

posted on 28/12/09 at 05:08 PM Reply With Quote
quote:
Originally posted by David Jenkins
^^^^^^

That's how mine is wired... except the 'test switch' is attached to my handbrake. Handbrake on, or low fluid, lights the lamp.


The handbrake switch is the legally required warning light bulb test switch (and has the good point of being automatic* since 'ordinary' punters don't remember to press the test switch). Its secondary function (not required legally) is to indicate you may have forgotten to take the handbrake off for people who can't tell why they are going more slowly than usual and there's a strange smell coming from the back of the car

* it also has one very bad point, Consider how many people not seeing the brake fail warning at ignition time would ignore the blown bulb as 'it's just a handbrake reminder!'





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Anonymous

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twinturbo

posted on 28/12/09 at 05:39 PM Reply With Quote
Since when was it a legal requirement to have a brake warning light?

TT

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flak monkey

posted on 28/12/09 at 05:40 PM Reply With Quote
quote:
Originally posted by twinturbo
Since when was it a legal requirement to have a brake warning light?

TT


Since about 1970, possibly earlier.





Sera

http://www.motosera.com

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twinturbo

posted on 28/12/09 at 05:45 PM Reply With Quote
That's strange as many production cars at least up to the mid 80's had no fluid warning, and some had not even progressed to the handbrake warning light.

TT

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David Jenkins

posted on 28/12/09 at 05:52 PM Reply With Quote
Not sure that I agree with Ian's "legal requirement" bit - but a switch attached to the handbrake is a quick and easy way to meet the IVA requirement for a way to test the "low brake fluid level" circuit & lamp.

If you're driving along and the light comes on - check the handbrake. If that's off, then pull over 'cos you're running out of brake fluid!






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boggle

posted on 28/12/09 at 06:19 PM Reply With Quote
early landrover defenders had no handbrake warning light......





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flak monkey

posted on 28/12/09 at 06:25 PM Reply With Quote
Fair enough. It was a guess. The mk1 escort loom I had had a dash mounted test switch.





Sera

http://www.motosera.com

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iank

posted on 28/12/09 at 06:36 PM Reply With Quote
quote:
Originally posted by twinturbo
That's strange as many production cars at least up to the mid 80's had no fluid warning, and some had not even progressed to the handbrake warning light.

TT


That "handbrake warning light" is actually the low fluid light! Which plays to my point about people not knowing what that light actually means.





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Anonymous

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iank

posted on 28/12/09 at 06:53 PM Reply With Quote
I'm struggling to find the original legal requirements in the construction and use regulations as HM Govt only puts acts post 1987 on their website.

Needless to say both the SVA and IVA regulations are clear on the requirement for a brake fluid warning lamp with a test switch of some kind (can be via the ignition switch and a timer, a switch on the dash or a handbrake switch), and have no requirement for a handbrake warning lamp.





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Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous

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twinturbo

posted on 28/12/09 at 07:32 PM Reply With Quote
Strange..

Anyway, as seems to be the case with lots of things it's not covered under the MOT.

TT

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speedyxjs

posted on 28/12/09 at 09:53 PM Reply With Quote
Cheers for the replys guys. No it wasnt fused so that would explain it.

Im not using a sierra master cylinder which is why mine works differently.





How long can i resist the temptation to drop a V8 in?

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iank

posted on 29/12/09 at 01:05 AM Reply With Quote
quote:
Originally posted by speedyxjs
Cheers for the replys guys. No it wasnt fused so that would explain it.

Im not using a sierra master cylinder which is why mine works differently.


Yeah, we are aware it's a Jag item, but afaik all manufacturers use the same method as it's the most simple. They don't tend to go around requiring relays as that's a couple of quid off their profit margin and a another thing to go wrong at some point.

Do you have a wiring diagram for the MC or the Jag it came from?





--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous

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02GF74

posted on 29/12/09 at 03:49 PM Reply With Quote
quote:
Originally posted by speedyxjs
I unscrewed the cap to make sure the light came on, it did but when i put the cap back on, the light didnt go out. If i unplugged the relay and put it back in again, the light was off so i decided the problem must be that i needed something connected to the 5th pin so (stupidly) i connected it straight to ground.

Switched the ignition on and have fried all the ignition wires





dude, never do stuff like that i.e. connect wires ad hoc.

there are a number of peeps that have good understanding of electrics that will provide advice so a little bit of patience would have saved a lot of hassle.






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