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> How common is the clutch cable becoming the ground?, My present clutch cable malady may be this issue....
second wind
post Nov 16 2023, 10:50 PM
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Hello all....I have been tackling a clutch cable problem and finally closing in on a solution....but my existing failed cable is so stubborn upon removal that it seems that the inner cable is welded to the outer housing....I have heard about the clutch cable becoming the ground for the car and I wonder how often this occurs and what are the symptoms?? I would like to prevent this from occurring while I am in clutch cable repair mode....thank you very much!!
gg
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second wind
post Nov 19 2023, 11:23 AM
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Thank you all....so is there a way to test the ground strap to see if it is any good? What makes it deteriorate anyway? Why and how does this negative phenomenon occur anyhow? Thank you again...
gg
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Superhawk996
post Nov 19 2023, 11:46 AM
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QUOTE(second wind @ Nov 19 2023, 01:23 PM) *

Thank you all....so is there a way to test the ground strap to see if it is any good? What makes it deteriorate anyway? Why and how does this negative phenomenon occur anyhow? Thank you again...
gg

Test ground strap by measuring voltage drop across the strap while cranking the engine. Should be very near to 0 volts - like 0.1 - 0.2 volts.

This can be done with a remote start switch or the help of a friend. I prefer to use a remote start switch and to have the DMM visible so I don’t have to be under the car. Something about not trusting other people when I am under a car. (IMG:style_emoticons/default/huh.gif)

Trying to measure the resistance directly usually won’t work due to limited resistance sensitivity of cheap meters. I have a couple that will read 0.1 ohms measuring just the resistance of the meter leads when shorted together.

Here’s the quick math per ohms law
Voltage = current draw x resistance

We want resistance in the ground strap = 0 ohms, therefore even when drawing lots of starting current, the voltage drop across the ground strap is 0 volts.

Example:

Let’s say we actually have 0.02 ohms of resistance in the degraded ground strap. Doesn’t seem like much. (IMG:style_emoticons/default/confused24.gif) using a cheap DMM - you likely can’t even discern this from the resistance of the meter itself.

Most DMM’s cannot directly measure this low of a resistance accurately.

But by measuring voltage drop across it when cranking, we can measure small voltages accurately - even with an El’ Cheapo meter.

So let’s say the starter motor draws 50 amps (could easily be higher).

Now voltage drop across the ground strap is:
Voltage = 50 amps x 0.02 ohms = 1 volt (easily read by any cheap DMM)

This is a lot of voltage to drop across a ground strap and would not be a good thing. It would not be good for the dreaded hot start issue. Likewise, if the resistance in the ground strap gets high enough (missing strap or severely degraded) the starter will try to pull current though a lower resistance path if one is available - which can be the clutch cable or sometimes the accelerator pedal cable as the Doctor alluded to.
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