How the hell does this happen?
Discussion
I've got a right odd gremlin that is actually bordering darn right weird. In short, on occasion my right indicator blinks at double speed. Nothing to weird about that I hear you thinking. The weird this is, it only does at one particular junction (two corners from my house)! Regular as clockwork! Beats the hell out of me!
Edited by srebbe64 on Friday 16th March 22:23
Phil C said:
Sounds a stupid suggestion - and it's a long shot- but try replacing the bulb(s). I've had all sorts of problems over the years with bulbs that haven't completely blown - but are playing up....
Many years ago I had such a problem with a bulb on my (then) Golf Gti - bulb had a filament that was detached at one end, but worked when it fell against the metal support, and not otherwise. Took a while to suss that one out. As bulbs are cheap, and darken with age, try replacing just to eliminate that as a cause.
Just to add a different angle to this :-
I believe that some traffic light control systems use an inductive loop buried in the road surface to detect waiting vehicles. My guess is that they work rather like big metal detectors, where AC energy is driven into a coil of wire and the amount of that energy that is inductively transferred to a second coil detects the presence of a vehicle. The large metal mass acts a pole piece and changes the inductance between the coils triggering the sensor.
So could be that if the wiring on the indicator circuit in question just happens to be a resonant length at the frequency used by the sensor it could be finding it’s way into the timer. This would seem particularly valid with a fibreglass car.
Diagnosing and fixing these sort of issues (if it is RF interference) is a bit of a black art but a starting point would be to connect some low value capacitors across the circuit, perhaps 0.1 uf or so, or / and fit a small inductor in line here and there.
I believe that some traffic light control systems use an inductive loop buried in the road surface to detect waiting vehicles. My guess is that they work rather like big metal detectors, where AC energy is driven into a coil of wire and the amount of that energy that is inductively transferred to a second coil detects the presence of a vehicle. The large metal mass acts a pole piece and changes the inductance between the coils triggering the sensor.
So could be that if the wiring on the indicator circuit in question just happens to be a resonant length at the frequency used by the sensor it could be finding it’s way into the timer. This would seem particularly valid with a fibreglass car.
Diagnosing and fixing these sort of issues (if it is RF interference) is a bit of a black art but a starting point would be to connect some low value capacitors across the circuit, perhaps 0.1 uf or so, or / and fit a small inductor in line here and there.
steve-v8s said:
Just to add a different angle to this :-
I believe that some traffic light control systems use an inductive loop buried in the road surface to detect waiting vehicles. My guess is that they work rather like big metal detectors, where AC energy is driven into a coil of wire and the amount of that energy that is inductively transferred to a second coil detects the presence of a vehicle. The large metal mass acts a pole piece and changes the inductance between the coils triggering the sensor.
So could be that if the wiring on the indicator circuit in question just happens to be a resonant length at the frequency used by the sensor it could be finding it’s way into the timer. This would seem particularly valid with a fibreglass car.
Diagnosing and fixing these sort of issues (if it is RF interference) is a bit of a black art but a starting point would be to connect some low value capacitors across the circuit, perhaps 0.1 uf or so, or / and fit a small inductor in line here and there.
I believe that some traffic light control systems use an inductive loop buried in the road surface to detect waiting vehicles. My guess is that they work rather like big metal detectors, where AC energy is driven into a coil of wire and the amount of that energy that is inductively transferred to a second coil detects the presence of a vehicle. The large metal mass acts a pole piece and changes the inductance between the coils triggering the sensor.
So could be that if the wiring on the indicator circuit in question just happens to be a resonant length at the frequency used by the sensor it could be finding it’s way into the timer. This would seem particularly valid with a fibreglass car.
Diagnosing and fixing these sort of issues (if it is RF interference) is a bit of a black art but a starting point would be to connect some low value capacitors across the circuit, perhaps 0.1 uf or so, or / and fit a small inductor in line here and there.
Interesting theory, but it has a fundamental flaw. Specifically, the junction in question is nowhere near traffic lights.
Still could be RF interference, have a look around the site and see if there is any obvious local source of RF energy. Is it line of site to the local taxi dispatcher, TV/ Cellphone / local radio mast or the like? Loads of things radiate RF and if you happen to have a resonant tuned length of wire (typically a quarter wave length at the interfering frequency will do it) hooked up to a high impedance point, it only needs a fairly small RF field to generate a surprisingly high voltage. The effect can be particularly pronounced if there is a bad connection that can act as a diode (just like the old cat’s whisker radios), to turn the RF into DC.
Your indicators will go double-time if there is a problem with the circuit. There was a broken circuit to my off-side front indicator which meant it wasn't working, so when I indicated right the other bulbs in the same circuit (side repeater and rear indicator) went double-time. Weird as to why it would happen at a particular junction though.... Does it definitely only happen at that junction?
I'm thinking it's perhaps something to do with a dodgy connection somewhere that only materialises when the car is at particular angle (e.g. the blub filament theory mentioned above)?
With no other cars about try indicating left instead of right at the exact same spot - could possibly help to rule out/confirm the RF theory? I'm assuming the RF would have the same effect even though the indicators are a few feet apart?
I'm thinking it's perhaps something to do with a dodgy connection somewhere that only materialises when the car is at particular angle (e.g. the blub filament theory mentioned above)?
With no other cars about try indicating left instead of right at the exact same spot - could possibly help to rule out/confirm the RF theory? I'm assuming the RF would have the same effect even though the indicators are a few feet apart?
Edited by jamiet on Monday 19th March 16:21
In my experience with older cars, fast winking flashers is always as a result of a dodgy earth somewhere. usually fixed by replacing the indicator unit, bulb, wiring, relay, solenoid etc. etc. until finally you rough up a bit of metal somewhere with emery paper and it's all OK again!
The reason for that effect is that the older systems used a BiMetallic strip timer. The current to the lamps passed via a strip of metal that was two different metals bonded together. As the current heated it one metal expanded more than the other and it flipped to the open circuit position. When it cooled down it then flipped back to the closed position. The problem with this system (or arguably a benefit) was the flash rate was determined by the load. As stated, if a lamp is open circuit or the wrong lamp is fitted the flash rate would change.
Could be wrong but My guess is that all Griffs will have a solid state timer fitted rather that the BiMetalic type. Last encountered one of those on an early 70s MG.
Could be wrong but My guess is that all Griffs will have a solid state timer fitted rather that the BiMetalic type. Last encountered one of those on an early 70s MG.
steve-v8s said:
Could be wrong but My guess is that all Griffs will have a solid state timer fitted rather that the BiMetalic type.
Nice theory, but many modern solid state flasher units are load sensitive by design ~ as a warning of bulb failures
Its probably alien abduction causing the problem.
Dave
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