Author Topic: Accelerating = turn signal?  (Read 3938 times)

batman

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Accelerating = turn signal?
« on: August 23, 2015, 09:21:43 »
Help - I have a turn signal light problem caused by using the gas pedal!!

I have replaced various dash lights with assorted LED's as per the threads on the forum and both turn indicator lights are now green 4-LED.

However, when I first accelerate and each time I depress the gas pedal but only after having my foot completely off it - I get a tiny flicker of both the green turn indicators at the same time, maybe for 1/4 of a second.

Why is this occuring - what could be causing it???

All other LED lights work OK, in the central cluster, tacho & speedo, including the turn signal indicators when I actually put them on to turn a corner!

Cees Klumper

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Re: Accelerating = turn signal?
« Reply #1 on: August 23, 2015, 11:01:07 »
All I can think is that it must be related to the mircoswitch that is activated when depressing the gas pedal from rest, that has some function controlling the three position solenoid on the auto transmission. That, and 'check the grounds' but I don't know how tou would go about diagnosing this. Others I'm sure will chime in with more helpful suggestions.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

michaelgread

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Re: Accelerating = turn signal?
« Reply #2 on: August 24, 2015, 12:45:50 »
Hi Mark,
LED's are fast acting and fire at a much lower voltage than a globe, and are generally current limited by resistors within the product housing.
The flicker is almost certainly caused by a voltage spike from the very large solenoid on the auto trans which is activated by the micro-switch on the throttle body when the gas pedal is pressed.
However looking at the wiring diagrams, the turn signal indicators on the dash are wired in parallel with the main turn globes, and those circuits are isolated from the ignition circuit until the turn switch is physically operated, so they should not see the spike unless the indicators are on.
Like Cees, i'm leaning towards a bad ground.
Mark are you aware that each instrument has a brown grounding wire that is connected to the instrument under one of the two thumbscrews which hold the instrument in place.
When working from the outside, it is easy not to notice those ground wires are there ??
I think this might be your problem....

66andBlue

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Re: Accelerating = turn signal?
« Reply #3 on: August 24, 2015, 17:31:13 »
...
Mark are you aware that each instrument has a brown grounding wire that is connected to the instrument under one of the two thumbscrews which hold the instrument in place.
When working from the outside, it is easy not to notice those ground wires are there ??  ...
I know that both the tachometer and speedometer have a ground wire under the thumbscrew but not the center cluster instruments. That one has its own ground wire within the cable bundle.
Could it be the charging circuit that creates the voltage spikes?
BTW, my green indicators do not flicker when I step on the petal and accelerate.
Alfred
1964 230SL manual 4-speed 568H signal red
1966 230SL automatic 334G light blue (sold)
1968 280SL automatic (now 904G midnight blue)

batman

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Re: Accelerating = turn signal?
« Reply #4 on: August 26, 2015, 22:59:21 »
Thanks Alfred, thanks Mike.

I took the car for a small night run last night (to test the power of my new LED's! and they do look fantastic) but also noticed that the red "door open/brake fluid" light is also faintly flickering as well on initial acceleration and gear change from second to third (although not to fourth which is odd.
So further investigation needed.