Jump to content
Click here if you are having website access problems ×

Faulty master switch


martyn

Recommended Posts

Just went down to the garage to run the car for a bit as it hasn't been used in a while.  Everything was completely dead. A quick poke around showed 12v on the battery.

Some further investigation showed that I could get power by pushing the master switch key in and wiggling it about a bit.

Up until now, I've never had a problem, including the last time I started it up - about 4 weeks ago.

However now, if I just casually insert the master switch and twist (like I always did) it doesn't work.  I need a concerted effort to push the master key in so I can feel the contact/spring compress before twisting.   Once powered up, I can let go of the key and it seems to stay powered - although I haven't tried driving like this.

Is this common?   Is it likely to be some fault internally with the switch or a bad connection/earth on the back?

Car is 8 years old – I presume the switch is also.  Switch is mounted in the usual location of the driver’s side scuttle.

I'm tempted to spray some ACF50 into the switch to see if that improves things, but if the switch is on the way out, I'd prefer to just replace it as I don't want it cutting out while I'm driving.

Link to comment
Share on other sites

I chased this exact fault around for AGES and it did my head right in. It'd normally manifest itself half way through a trackday when I lost most of the electrics. And then a pal casually said screw a very short screw into the end of the FIA key so that it makes better contact and bottoms out harder in the socket. Lo and behold, 5 years later, my bodged up key still works perfectly.

I have a few spare red FIA keys if you want one to have a play around. I'll also send you a picture of my modified key if you like, as the description above may not make complete sense without seeing the modification.

Link to comment
Share on other sites

Thanks, that's interesting.  I can visualise a screw in the end so that only the head protrudes, effectively making the key longer.  I guess I'd need one with a fairly shallow head - a millimetre or two?

Could this be caused by wear to the switch's internal "screw thread" - meaning that the rotation doesn't cause enough forward pressure? Otherwise, if its wear to the key itself then presumably a new key would fix it?

Link to comment
Share on other sites

It's a common problem

It's a switch where the contacts don't "wipe" over each other when activated, they just press together. Over time the contacts then get dirty/oxidised and break down. I super glued a small washer onto my key when it happened to me

Link to comment
Share on other sites

  • 1 year later...

Does the suggested bodge (screw or washer) add a milimetre or two to the insulated length of the key? If so is the aim to shift the metal part of the key a millimetre or two away from the car/bulkhead and nearer to the person using the key so it applies pressure to a slightly different part of the contacts?
 

Link to comment
Share on other sites

Can you please clarify where the screw/washer needs to be fitted to push the contacts closer? There is just a small piece of metal that sticks out from the side of the key so I'm not sure how contact can be improved. The only thing I can think of is to make the central plastic core a bit longer with a screw or washer which may cause the pressure area on the contacts to shift slightly.

Link to comment
Share on other sites

  • 2 weeks later...

I did the screw in the end and it worked well. It did cause the plastic core to swell so it did not fit but filing  overcame this. I'm not sure if this is a good long term solution as all it does is slightly shift the main pressure area on the contacts so it may fail again but it has given me a good spare. I have bought a new APS switch from JJC via Ebay for £10something.

P1020336.JPG.3986f105a25d6e5a2b7d80bce7f3853b.JPG

P1020337.JPG.5609ad3d7fe8f835a329c7ee41e6dc7c.JPG

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...