N19's fleet - Mondeo brake warning light excitement

[N19]

The diagram posted does miss out the handbrake switch itself which is earthed on the right, just out of view. However, you're correct that I think I have misunderstood. Unplugged the multi plug today and it's still permanent on. I guess the next check is to short all 3 pins together (the opposite condition to open circuit) and see if that has any effect. 

I have parked the Mondeo up behind my own flats in the wider of the parking bays, as there's actually some space there to work, and I'm intending on replacing the foglights too (they've fallen to bits with corrosion, as I discovered when untwisting to change a bulb) and do a bit of wire brush and paint job on the underside. 

[Andrew353w]

The brake warning is wired on a "fail safe" system, which means that the light will illuminate if there's a problem with the brakes (low fluid and/or handbrake on) AND/OR there's a problem with the wiring. This is to alert the driver to a brake problem and/or a wiring problem.  It's better to be safe rather than sorry, and that's why the system's wired in this way. A good analogy is to think about air brakes on trucks & trains; if there's a problem with the vacuum the brakes are automatically applied, hence the 'fail-safe' phrase.

 D.M. me if you want more help-happy to pop round chéz vous sometime.  

[N19]

Yes, I assume it's logical to 'fail safe'; which is presumably what it is actually doing - so it's doing its job well!

May give you a shout later in the week @Andrew353w when I've a bit of time to look at it - thanks!

[N19]

I had ordered a decently-priced m/c and brake fluid reservoir, just in case, last week. I had a look today - I think when I drew off the brake fluid previously, it took off only half of the circuit's fluid, leaving some in the other half of the reservoir, hence the switch was reading ok as, err, it was. The reservoir (empty) which I have here has continuity between all pins, which is how it 'should' be according to the diagram in its condition... I think. Anyway, if you plug the multi plug into it, the brake light glows bright red rather than just the mid-dull it is stuck on. So it's definitely something wiring related.

New foglights due in the next couple of days, I'm sorting out a few bits and pieces where trim (e.g. the front grille) has snapped clips and fixing points. I've glued a replacement bit of metal in, to replace the cable tie that kept one half of the grille sitting in position for the last year, and have tiger-sealed the outer surround back on as the original adhesive was falling apart.

[N19]

A couple of bits done at lunchtime. I think the next thing to do will be to test the link between the brake fluid reservoir and the dash, based on the diagram, so a start made in taking the dash apart.

I also tested every fuse in the fusebox, just in case something had blown. The only thing blown is the heated seats.

Also had a look at the bumper, which the spray paint has flaked off in a couple of places, to see about re-doing that while I'm at it.

The paintwork in general is in pretty poor nick with laquer peel and scratches everywhere. I don't know the first thing about polishing and all the like. Is it worth having a go with some t cut or something else?

[danthecapriman]

T-Cut and polish etc will probably help a bit with ingrained grime and light marks but anything down through the paint or lacquer peel it won’t do a thing. The polish will help keep moisture out but that’s it.

Anything that’s gone through the paint will need either spraying or a touch up paint, then you wet sand it down with progressively finer grades of paper, then polish over that. 
Lacquer peel is a pain to sort too. You could wet sand the loose damaged bits then respray with new lacquer but if it’s peeled in places the chances are it’ll just start going all over sooner or later. My Volvo roof started off with just odd tiny bits of peeling and within a couple of years it now has barely any lacquer left on it. Ideally it needs the whole roof flatting back and re-lacquering but it’s not a job I really fancy!

 

[N19]

To do a bit of testing, I used a highly advanced* method, connecting the connectors via test leads and, err, bent paperclips. Frustratingly, it seems the only circuit diagram in the Haynes book is from a Mk1 Mondeo - trying to find the pinout at dash end, since the fault seems to lie between the brake reservoir and the dash. More after lunch.