XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

Where to connect the earth on the back of the instrument cluster?

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Old Nov 22, 2020 | 10:10 PM
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Default Where to connect the earth on the back of the instrument cluster?

Attached is the back of my 1992 instrument cluster. I am wanted to add an extra earth wire(have read a lot on these forums that it’s a good idea) while I have it pulled out. Are the screws that I a pointing at with the pliers in the photo a good spot to start? If not where would you recommend? I can’t find any exposed metal/steel on the cluster.
 
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Old Nov 23, 2020 | 01:25 AM
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If you rotate the cluster, as the photo shows the rear vertical surface, and post a photo of the top surface ( hardly visible in the photo) we can show you where to place the earth. The screw you point to will NOT do the job.
 
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Old Nov 23, 2020 | 08:02 AM
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Greg in France, thank you for the feedback. Here are two photos of the top of the cluster.



1992 XJS V12
 
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Old Nov 23, 2020 | 06:32 PM
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Gee what's the yellow hoop on the oil pressure gauge? My 93 doesn't have one, looks homemade, possibly a ground?
 
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Old Nov 23, 2020 | 07:25 PM
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Timeisrelative I have no idea what it is. Must be from when the other guy had it. But the Oil pressure gauge seems to be working fine. That is, until the car heats up to temperature and the the pressure indication drops very low (dont know if its just a pressure sensor issue, the car seems to idle fine)?
 
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Old Nov 24, 2020 | 12:34 AM
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SD
The later cluster in your car (I only have experience of pre-facelifts) does not have an obvious earth bar running along the top of the cluster. This means that all the earths are running along the copper traces back to the plugs. So I am sorry to say i cannot see where an extra earth wire can be easily fixed to. Perhaps other facelift knowledgeable guys can help?
What specific problem are you trying to cure?
 
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Old Nov 24, 2020 | 07:45 AM
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PLEASE DOUBLECHECK MY DIAGRAM

The following shows you which points are grounds. There are two more, not included in the picture. The two three hole clusters, also protected with rubber caps, well the upper one has a ground point on the right-most hole. (three o'clock) The lower cluster has a ground on the top hole of the cluster. (12 o'clock)

What I did, was run a heavy gauge copper wire to connect all of these points together, with a pigtail, which connected to yet another point behind the dash. I can't recall exactly where, but I checked it with a multimeter, and it showed a solid ground.

It was tough because the rubber caps no longer seated properly and it was a challenge to find a point to get that 16ga wire out to the ground post behind the dash, but I did it.....and it did not fix my fuel gauge cluster unfortunately.

The ground post I found was at the door side of the drivers side of the car. Somewhere close to where the lower part of the dash met the frame. It was kind of difficult to get the bolt back on, but I was able to get it on.

 

Last edited by Vee; Nov 24, 2020 at 07:48 AM.
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Old Nov 24, 2020 | 08:19 AM
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I thought I had a picture of what I did!


 
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Old Nov 24, 2020 | 06:33 PM
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Greg in France thanks. Trying to get my speedometer to keep from dropping off. It will loose power intermittently and seems to happen when the voltage meter drops low (around 10). When the speedometer is working the voltage meter is reading good about 12-12.5 volts.
 
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Old Nov 24, 2020 | 06:38 PM
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Vee, thats awesome thanks for the picture! As I was telling Greg in France, I have noticed my speedometer will drop down to zero when the voltage meter gets around 10 volts but then when its up to 12-12.5 volts it starts working again. Not sure if its not getting a good connection to provide the instrument cluster with the proper amount of power and just needs those extra ground wires. Or the alternator is about to crap out on me. Were you experiencing a similar problem?



1992 XJS V12
 
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