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MG TD TF 1500 - Signal turn / flasher failure

I have been working on fitting some separate turn signals on my MG TF.

All looked good on the test fitting but on tightening the new signal in ( it is a motor bike signal - pod on top of a stalk ) I pinched the live wire and create a short.

Burnt out the fuse ( 25A). Replaced fuse.


The only fuse left was a 35A from my MK2 Jag (there weren't any obvious labels on it)

Gave one flash and failed again. I stripped it and yes I had pinched the live wire.

This time though the fuse didn't burn out...Looking at it more closely (glasses on and magnifying glass to hand) the metal strip is pretty thick and it reads F35AL250VLAC. Doesn't sound good. Reads like it would work on a domestic power supply ( we are 220-240v power supply in Ireland


Now when I turn on the indicators the front side lights come on ( brightly) and stay on. The rear doesn't light up at all. Neither does the indicator light on the dash.

The dimmer running lights function front and back work on their own. Brake lights work so bulbs are fine. Car starts. Head lights work etc etc


So :

If I have burnt out the flasher unit ( most obvious failure ) then why do the front side lights come on?

Surely the circuit should be either stuck off ( neither front or back lights work) or on ( both work and stay on)

Confused...and hoping I haven't brunt out something more expensive...

Dave
D Moore

Dave,

Just a thought after a quick read through your story. Could one or more sets of points on the regulator box be burned or pitted or fused together.

Pull the box cover (it comes off without having to remove the box from the car)and check out each set of points. Look carefully as there are five sets on each electromagnet, as I recall from dealing with the box years ago. Perhaps someone else more up to date can give you more.

Gene
G Burgess

I have been mulling over the same possibility myself. I hope not / that they are easy to repair for the non expert...somehow I don't think so...

Dave
D Moore

Think I would try disconnecting the "new lights" and see if they still function correctly.
Been a long time ago ...but believe I had a similar problem years ago when I added extra lamps.
A different flasher cured it for me.
(The old one could not take the extra load.)

Let us know...I can see if there is a part number on mine.

Is your car still positive ground?
Mine has been changed to negative ground.
Could be a short in the new fixtures dependent on how they are wired?
David Sheward "IZZY" TF 7427

Dave M. (we are getting entirely to many Daves around here) - "This time though the fuse didn't burn out...Looking at it more closely (glasses on and magnifying glass to hand) the metal strip is pretty thick and it reads F35AL250VLAC."

The MKI eyeball is the absolute worst diagnostic tool for checking a fuse (even with glasses and a magnifying glass). Get yourself a cheap multimeter and learn how to read the the ohms (resistance) scale, then check your fuses with that. Fuses can come detached under the end caps where you can't see with any vision aid, of it can become partially blown, developing a high resistance, neither that can be seen. Cheers - Dave D.
David DuBois

Dave ( Sherwrad) : I disconnected the new lamps - no joy :-(

Dave (DuBois ) : Excellent advice on the short comings of the MK1 eyeball. I have a multimeter - it just never occured to me to test the fuse :-( Should have known better - and do now.

Thanks

Dave
D Moore

Dave Moore

Other place I would be inspecting is the brake/flasher relay box, you may have contacts welded together.

Flasher units are very subject to failure if exposed to any form of short circuit.

Graeme
G Evans

"Flasher units are very subject to failure if exposed to any form of short circuit."

My thoughts exactly...also very cheap to replace!
See if a new one corrects the problem with "new lamps" still disconnected.

Many "MC" type lamps I have seen are grounded to the mount. If the car is still positive ground...that could be the source of a short.
David Sheward "IZZY" TF 7427

I did some research and found a very good book ' Classic British Car Electrical Systems'

Gave a simple test for flasher failure. Put a jumper between the power X and lamp L terminal and put the indicator on.

If the lights go on ( they won't flash) then he flasher has failed.

Mine had. By a miracle one of the local auto stores had exactly the same model as mine. Not a surprise perhaps in the US - but in Ireland... well I was stumped.

So flashers back in action :-)

I have another problem now... when the brake is applied the indicators come on - but not the brake lights...

Time for separate thread.

Thanks gents.

Dave

D Moore

My wife bought that book from Amazon or Ebay for me a couple of months ago. It's an excellent resource that I refer to regularly. I keep it right next to the WSM.

Jud
J K Chapin

Dave ...sounds like your on to the brake light switch now!
Suspect something in the new lamps caused a serious short at some point.
Before you hook them back up...maybe put an in-line fuse in the circuit to test first.
David Sheward "IZZY" TF 7427

This thread was discussed between 10/02/2014 and 12/02/2014

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