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Lada Indicator/Dash Lighting Interaction

Posted: Sat Sep 09, 2017 11:47 pm
by Zelandeth
Now my background is in electronics and electrical engineering...so I'd not expected this sort of thing to send me on such a merry old dance...

When you first turn the ignition on in my Riva, the indicator tell tale on the dash blinks once, accompanied by a click from the flasher unit. Nothing happens with the actual indicators outside (which you'd expect given that they're "downstream" of the flasher unit in circuit)...it's just the flasher and dash lamp.

Thereafter the indicators/hazards behave completely normally. Until you turn on the headlights - when you get another blink from the indicator light on the dash. At some point...It can be immediately, half an hour or not at all...the flasher unit and light on the dash will start blinking rapidly as though you're indicating but there's a failed lamp somewhere. Turning down the dash lighting rheostat sometimes (but not always) will stop this madness...which usually quits itself after a while. It may then come and go until you either get to your destination or turn off the headlights.

Now I'm pretty sure that this is an earthing issue, which is causing power to back feed into the flasher unit from somewhere it's got no business to be doing. However I've so far been utterly unable to figure out *where" it's happening. It's not a complicated wiring system so there's only so much to go wrong!

I've had both headlights out and have cleaned up all the earths around them, likewise the tail lights, pretty much every accessible ground behind the dash and down by the rheostat. Cured several squeaks while I was at it as several were loose - and two of them double up as attachment points on the bulkhead for the dash...which unsurprisingly was moving as the nuts holding it on were only finger tight.

The only thing I can think that it might be that I've not tried anything to resolve is potentially a dodgy indicator switch itself...though that doesn't explain the interaction with the headlights.

Before this drives me any further to distraction, what really stupid, blindingly obvious thing have I missed.

Re: Lada Indicator/Dash Lighting Interaction

Posted: Sat Aug 04, 2018 2:19 pm
by Zelandeth
Just to close this off, the fault turned out to be a problem with the flasher unit itself.

It was obviously a later replacement (albeit still of Russian origin), and I stumbled across one of the huge old Lada flasher units (they're about the size of a cigarette packet) so gave it a try.

Immediately resolved the problems I'd been having and also restored a loud enough tick that I can actually hear it above 20mph now.

Moral of the story...new parts aren't always good parts!

The usual failure of the old units is the braided copper supply lead coming adrift of the moving contact on the relay itself. With a decent soldering iron this is easily fixed.