Hi folks,

I have been traveling a lot and my Jag has been sitting for a week or two at a time. I was not surprised when it cranked slowly, figuring the battery was getting weak.
I swapped out batteries with another car of mine, and the problem persisted.
With the car running the voltage at the battery was 12.2 volts. Great, the alternator, I thought. But when I checked the false bulkhead connector, the voltage there was 14.3 volts. Hmmmm.

Yes, I'm another victim of the engine ground strap. 10 minutes of fiddling under the car had the ground strap cleaned up and problem solved! So if your Jag is slow to crank, check the voltages at the battery and the engine. I had 2.5 volts difference between the engine block and the chassis while it was running.

I hope this saves someone some time and money in the future. Thanks for all the helpful hints I've taken from this site.

 

Thanks for the update, good to see it was that cheap and easy fix

 

Rob,

Great diagnosis. I'm new to this forum, but, not new to electrical mysteries on cars and trucks. I've seen many parts changed and time/money wasted chasing what turned out to be a voltage drop problem like yours.

A voltage reading taken from the negative post to the negative battery terminal, body ground, and engine block can indeed save headaches. A cranking test can help find less extreme problems that can be repaired before they cause bigger problems.

Thanks for sharing,
Joe

 

Just to shortcut some fumbling around, where IS the engine-to-chassis ground strap on these cars?

 

The strap on my 99 VDP naturally aspirated is on the passenger side from the frame rail to one of the transmission to engine mounting bolts.

If you look on the left side of the transmission in this picture you can see the strap dangling there between the transmission bellhousing and the frame of the car.

 

On mine it is on the right hand side, just behind the front wheel. It goes from the transmission to the frame rail, it's hard to miss. Scotchbrite and a brass brush cleaned up the surfaces and all is well for zero cost.

 

I'm unable to completely remove the bolt that connects the ground strap to engine/transmission as the head of the bolt makes contact with the passenger side catalyst when attempting to remove it. Have any of you encountered this and if so, do you have any suggestions/tips on how I might be able to get this bolt out without having to resort to a sawzall?

 

The bell housing bolt on my 98 XJ8 is too long to extract also. I just cleaned the contact points the best I could with emery clothe and greased them up.

 

I cut my cable off, and installed the new cable on a different bolt.

 

did that fix it avt007??

 

Yes, it did. Look in my signature, and you'll see a link to an electrical troubleshooting presentation that I made. It will walk you through all of the possible problem areas for this kind of a snag. Let me know if you need any help.