As a long term British car owner (MGs, Triumphs, Rovers, Healeys, Wolsleys, TRVs and even Jags), I've come to know the value of having good ground (earth) connections. All sorts of seemingly unrelated issues and gremlins can be traced back to bad grounds and I'm sure my '03 XJ8 is no exception. The X308s seem to be particularly sensitive to battery condition and electrical connections.

As part of the PM I will be doing on this new-to-me car, I want to go through all the ground points and redo them, just for good measure. Can any forum member please let me know where they are? (I haven't received my manuals yet).

Thanks for the help!

 

Go to jagrepair.com and download the manual for your car, free. It will show you exactly where the ground points are.

 

jimbov8: Thanks for the excellent resource. Hadn't seen this one before. I fear I might just burn up my printer, but that's cheap compared to fixing a broken kitty.

Now let me rephrase my question...

Of the 23 Ground Point Locations illustrated in the XJ Series Electrical Guide, which are the most critical and troublesome and should be cleaned and made secure??

Thanks!

 

The one leading from the bellhousing to the underbody
is often cited because it is exposed to underspray.

When you remove the underbody end you will find that
contact is mostly through the star washer and bolt. The
area around the bolt hole is still covered in primer.

I prefer to consider the ground side as a ground plane.

One of the most important paths that is almost always
forgotten is the path leading from the alternator through
the alternator bracket and then to the engine.

I took it all apart, shined up the contact points with
emery paper and then reassembled with conductive
grease bought from Home Depot.

As for "critical", take a look at the wiring diagram and
see what circuits they serve, and consider their physical
location. A ground point within the cabin is less likely to
give trouble than one that is exposed to the elements.

But, you did say ALL ground points. So, why ask which
ones are critical?

 

LeLimoMan,

In addition to plums' excellent advice regarding the engine ground strap and alternator bracket, I would suggest you then clean all the other engine bay ground studs, plus any others used by the ECM and TCM, which you will find in the Electrical Guide.

Note that in the Guide the page before each schematic lists all the components (modules, lamps, sensors, switches, etc.), relays, electrical connectors, and grounds associated with that system. It also gives a brief description of the location of each item. Over the years I have found the information on these pages to be just as helpful as the schematics themselves.

For example, on the Engine Management System schematic you'll see that the ECM uses three grounds. Referring to the previous page, you'll find that two are located on the firewall/bulkhead (left and right) and one is at the "EMS LH Ground Stud." Now refer to the ground location diagram (pdf page 23 in the 2001 version of the guide, which probably applies to your '03 as well). The diagram shows the EMS LH Ground Stud is on the left front inner fender/wing.

Check the schematic for the TCM to find its ground(s), but if you'll do all the grounds in the engine bay plus the ones at each A-pillar you'll cover most of the critical circuits. Add to those the grounds in the trunk/boot and the battery terminals, and you'll avoid most ground-related gremlins for the next few years.

Any time you're working on the car and notice a ground stud or battery power connection you haven't cleaned before, go ahead and clean it preemptively (disconnect the battery before touching battery power connections).

In addition to all the documents available at jag-repair.com, courtesy of our forum member Gus, also download this excellent Electrical Troubleshooting Guide created by our forum member avt007, aka Rob:

http://www.mediafire.com/download/qq...leshooting.pdf

And please take a moment to send a message of thanks to Gus and Rob!

Cheers,

Don

 

Don: Thanks for the excellent advice and the resources. This is why I belong to forums like these. Great people, shared experiences, invaluable resources and a wonderful sense of community. I have just such a forum for my motorcycle (Suzuki Volusia) and it's the same over there.

I'll indeed check out the link for the troubleshooting guide and will be sure to drop the fellows a big thanks. While I'm sure that they are handsomely compensated for their efforts (Right!), it never hurts to say thanks.