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Author: Subject: MSA master switch issue ?
gixermark

posted on 14/5/12 at 10:53 AM Reply With Quote
MSA master switch issue ?

another snag i have......

after a few laps my dash display disapears... and with it my transponder (direct wired) which seems to upset the officials somewhat...

i had the transponder wired into the ignition switch initially.... but then gave it its own feed direct off a spare circuit on the fuse box.... and same thing happened. I also replaced the fuse box (easy thing to try)

am now thinking it may be the master switch ? i've never had the pleasure to investigate the wiring of a master switch, but i guess it must connect to all positive feeds on the carm and maybe the feeds going to the 'accessories' end of things is a bit tempermental ? although not sure why it works every time in the paddock/garage... and only fails after a number of laps.

thankfully the engine keeps singing - its got an elec water pump/fuel pump... injectors etc so it keeps doing its thing while the rest of the car goes to sleep..

any ideas ??

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HowardB

posted on 14/5/12 at 11:54 AM Reply With Quote
if as I suspect the master switch should kill everything, then the fact that the engine still works suggests that the fault lies elsewhere. My initial thoughts are that you have a vibration/heat induced earth fault. An easy test would be to run a separate wire from the battery neg to the dash/transponder and see if this fixes it?

hth





Howard

Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)

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gixermark

posted on 14/5/12 at 12:44 PM Reply With Quote
good point........

the heat one sort of makes more sense... although it could just be a bad connection somewhere as you say.

possibly one step in the right direction is to give the transponder a new (direct) earth feed next time out, and see if it at least behaves... if the dash still goes out - them we most likely just need to feed it a new earth too.....

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procomp

posted on 14/5/12 at 06:04 PM Reply With Quote
Hi

Mark the switches are notoriously crap. The main problem is that the two brass contact inside eventually make less pressure as a contact and results in various problems. A quick bodge fix / conformation off the switch or problem else where is to increase the pressure on the contacts by sticking a packer ( 2mm thick washer ) in the hole then the key, that significantly increases the pressure. If that cures the problem replace the switch as the brass terminals are buggered.
If problem persists obviously problem else where.

Cheers Matt






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gixermark

posted on 14/5/12 at 07:15 PM Reply With Quote
fine suggestion Matt - I will try that next time... I woudl have thought if the master key was a bit dodgy, then all circuits would fail - but like you say, they ain;t the most reliable bits of kit - and thats definately worth a punt

[Edited on 14/5/12 by gixermark]

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