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MG TD TF 1500 - TF 1500 Flasher Wiring

Having a problem with the dash panel flasher indicator light and no matter how hard I stare at the TF wiring diagram in the WSM page N29, I can't find any sign of a flasher unit. Can anybody explain this to me? Archives on flasher problems have lots of good info but no mention of this (perceived) issue.
T W Moore

Operation Manual P71:
"Direction Indicator Warning Light" in the instruments group.

Matthew.
M Magilton

About an inch to the left of "fog lamp SWITCH" is the "DIRECTION INDICATOR WARNING LIGHT" with a #66 wire (Light green) leading down to the "P" terminal of the flasher. Bud
Bud Krueger

My question concerns the wiring of the turn signal indicator system. The flasher unit ( a Tungsol 550 ) is located under the hood(bonnet) on the side of the battery box. The "PLX" unit which IS shown in the wiring diagram is under the dash and feeds the direction indicator warning light with a light green wire.
What puzzles me is that I can't find the flasher unit on the WSM wiring diagram anywhere.
What is the function of the PLX unit? The PLX and the flasher presumably have different functions. And what represents the flasher on the wiring diagram, or is it just missing, like the windshield wiper switch.
T W Moore

The PLX unit is the flasher can, just to the right of the DIRECTION INDICATOR RELAY UNIT on the wiring diagram. Bud
Bud Krueger

This help? N.29


David Sheward 55 TF1500 # 7427

I would also have thought that the PLX unit was the flasher, but if so, why is there another flasher (the Tungsol cylindrical) unit in the engine compartment.
And, at the risk of appearing repetitious, where is it on the wiring diagram.
T W Moore

PLX ("FLASHER" marked above) is the unit attached to side of battery box.
David Sheward 55 TF1500 # 7427

OK with that. The box under the dash looks like a relay installed by a previous owner. I thought it was in lline from the signal flasher switch.
Thanks for straightening me out.
T W Moore

The extra relay may be part of an anti-theft set up. Or a PO has tried to get round the brake/indicator lamp connection
Any chance of a photo.
Ray TF 2884
Ray Lee

TW, with the help of Rick Astley's Electrical Systems book (see schematic attached)I have deduced the following:

There is both a relay box AND a flasher module (the PLX can is shown as item 25). The sole function of the PLX can is to cause the circuit to pulse by heating a coil to open a relay contact. When the coil then cools the contact is remade and the circuit is again energized. That's all it does though - just turns on and off so long as electricity is supplied to it through the directional indicator switch. What's done with that pulsing electricity is determined by the relay box (item 51 in the attached schematic). The beauty of this is that a single PLX can provides pulsing electricity to either the left or the right turn signals - there is no need for a left turn PLX can and right turn PLX can.

On my TD (see image attached to next post) the relay box is located way up under the scuttle near the steering column. The PLX can was attached to the battery box but I felt that the raw aluminum can looked hideous so I relocated it under the scuttle out of sight near the relay box.

The Astley explanation of how all of this works together goes on for a page or two so I won't describe it all here but I recommend his book if you want to know the nitty-gritty of how electrons and TDs coexist.

Jud


J K Chapin

Here's my relay box up under the scuttle.


J K Chapin

This thread was discussed on 06/04/2015

MG TD TF 1500 index

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