What did you do to your XJ today? 1M Views

[Roler]

Ok, but my question remains: How do I check if a certain point in the trunk (or anywhere out of reach from the neg battery terminal using my multimeter) is a good ground/earth?

[Billnick]

I think you are looking for a problem that wont be there after following the advice from fellow posters. If the leads are too short, extend them. Shiny up the metal, fit your ground terminal then run a temporary wire from the neg battery terminal back to the rear of the car. With the scale on OHMS touch the meter leads together and note the reading in case of any error in the meter (my dodgy meter shows an error of 1.2ohms) then touch one lead to the wire coming from the battery, the other lead to the cable attached to the car ground that you just fitted. The reading shouldn't be any more than 1 or 2 ohms difference. Alternatively you can attach your temporary lead to the positive terminal of the battery, change the scale on the meter to DC VOLTS and check the reading which should be very near the same as the battery voltage ie about 12.5v with the engine off, 13.75v engine running.

The temporary wire doesn't have to be special wire, you can use a 240v extension lead, fencing wire, clothesline wire or even the heavy positive wire you ran for the second battery.

[Roler]

Aaaah, I now see the light (halleluja) .
It was likely my nightshift brain that could not follow. Thanks Billnick, it made it clear what Oldon, JJ and others already tried to tell me so, thanks to all.

[junglejuice]

Originally Posted by Roler

Ok, but my question remains: How do I check if a certain point in the trunk (or anywhere out of reach from the neg battery terminal using my multimeter) is a good ground/earth?

Roler, with the equipment that you have (most likely) you're not going to be able to tell really the difference between a great ground and a reasonable ground as most DMM's can't read low ohms accurate enough to show the difference, what will happen is when the higher currents are applied like what is used to charge the battery then this will show up an average or poor ground with voltage drop across the ground connection but you won't know until you try it.
So yes you can extend the probe cable and yes it may show continuity but realistically it won't really tell you much.

So, remove the trim, find an existing hole in the metal work, clean off the paint, connect you ground, vaso it, and try it, save yourself some time and give it a go, you're going to get voltage drop anyway but at least you can measure where it is and then work out how to sort it....

[Roler]

Originally Posted by junglejuice

Roler, with the equipment that you have (most likely) you're not going to be able to tell really the difference between a great ground and a reasonable ground as most DMM's can't read low ohms accurate enough to show the difference, what will happen is when the higher currents are applied like what is used to charge the battery then this will show up an average or poor ground with voltage drop across the ground connection but you won't know until you try it.
So yes you can extend the probe cable and yes it may show continuity but realistically it won't really tell you much.

So, remove the trim, find an existing hole in the metal work, clean off the paint, connect you ground, vaso it, and try it, save yourself some time and give it a go, you're going to get voltage drop anyway but at least you can measure where it is and then work out how to sort it....

(I think we were typing at the same time)
Yep, got it.

[oldon]

Originally Posted by Roler

(I think we were typing at the same time)
Yep, got it.

wall:

[darksidecustoms]

Wrapping this job up today. Will be great to get rid of the torque steer

In other news, I never want to deal with drum brakes again...




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