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+--- Thread: That inertia switch again! (/showthread.php?tid=2489)
That inertia switch again! - matclarke - 02 Oct 2009
Hi everyone!
I thought I'd reposition and rewire the inertia back into where it should be, but it came to testing it, nothing happened!
Thought the engine might stop!?
Anyway, here's a picture that pretty....
![[Image: th_inertia.jpg]](http://s191.photobucket.com/albums/z251/matclarke01/?action=view¤t=inertia.jpg)
Tested them electrically:- the double wired lighter coloured one has about 0.06 DC volts, and the two dark wires, (that were wired together since I bought Frenchy!) work nicely as an earth....
Any clues?
Ta, Mat
Re: That inertia switch again! - stunned_monkey - 03 Oct 2009
They're all ground.
Black = Permanent Ground
Black/Purple = Fuel pump -ve
Brown/Pink x2 = Central lock module "unlock"
The idea is that under normal circumstances the fuel pump -ve is connected to ground, but if you crash, the fuel pump is cut and a ground is put on the central locking making the doors automatically unlock.
The reason the inertia switch was relocated was that the driver could accidentally kick it, and also with a large enough mallet, the car could be unlocked by thumping the inside of the wheel arch to trip the inertia switch and pop the locks.
The wiring to the fuel pump goes through a 9-way multi plug that's accessible by removing the washer bottle cowling.
Re: That inertia switch again! - matclarke - 04 Oct 2009
Thanks for that, I now understand the principle, but still slightly confused...
As nothing happens to the doors or fuel pump when I trip the switch,
are you saying I need to find this 9-way multi plug and make sure the wires still tally up
with the ones I find in the footwell?
Ta, Mats
(Thanks for the adhesive advice as well!)
Re: That inertia switch again! - stunned_monkey - 04 Oct 2009
Well firstly the doors would have to be locked for the inertia switch to trip them... in case that wasn't obvious!!!
You almost certainly need to replace your switch - the chances are that Frenchy is one that "slipped the net"
http://www.dmcnews.com/bulletins/SC-06-7.82.html
Re: That inertia switch again! - matclarke - 04 Oct 2009
Oh, err yes, of course! I knew that! :oops:
Will try that again with the doors locked....
But the engine definetely didn't stop like I thought it would....and it's a brand new switch...
Watch this space about the doors....
Cheers again, Mat
Re: That inertia switch again! - stunned_monkey - 04 Oct 2009
matclarke Wrote:But the engine definetely didn't stop like I thought it would....and it's a brand new switch...
Oh! well I'm a bit stumped then. Next step for me would be to continuity test the switch to see if it swaps as it should.
Re: That inertia switch again! - matclarke - 05 Oct 2009
Good plan...will test the switch...
Although I remember in a fit of confusion I unplugged it (with engine running)
and touched the wires together in different orders to no avail....
I thought that that might be a tell tale sign that all's not well within the wiring?
Cheers, Mat
Re: That inertia switch again! - stunned_monkey - 05 Oct 2009
If you un-plugged the switch and the engine still ran, then the fuel pump must be getting a ground some other way...
Re: That inertia switch again! - matclarke - 05 Oct 2009
Great Scott...
Martin, you're a genius!
I've just remembered a little while ago I was having a few bad weeks with the fuel pump not working, until a stray wire literally just came floating by, which turned out to be a very good earth, earthing itself close by onto the chassis.
The original black wire I taped up and forgot about.
HENCE why the inertia switch doesn't do its job!
Mmmm this sounds like a serious rewire to get it to back through the inertia switch.....
Cheers again Martin....
Re: That inertia switch again! - stunned_monkey - 07 Oct 2009
You've got me mightily puzzled too cos I fitted your pump....... :?: :?: :?:
Re: That inertia switch again! - matclarke - 07 Oct 2009
Yes I know... :?
Less than a year ago I was having trouble starting the D and with bits and pieces off/bonnet open I just happened to notice the deathly silence coming from the fuel pump.
It was getting the right voltage, and I experimented with grounding it to the chassis, which seemed to work, which led me to the duff earth lead that's normally plugged into it....
There happened to be a black wire tied neatly close by - screwed into the part of the lower left front chassis - not doing anything, so I connected that one in instead and that was the end of the starting problem!
I assume that if I use the new wire to somehow route through the inertia switch, all will be well!?
Cheers,
Mat
Re: That inertia switch again! - stunned_monkey - 07 Oct 2009
It depends if the problem in the original loom is between the inertia switch and ground (in which case yes) or between fuel pump and inertia switch (in that case, no)
I'd put money (maybe 50p
) on it being a problem with the multi-way up where the washer bottle is.