Hi 49Markvman,

On our '04 with HID headlamps, the lower ground stud on the right side was not easily accessible, due to the proximity of the headlamp housing to the end of the stud. See my discussion a few days ago with plums and my photos in post #9. Does your car have HID lamps or standard Halogens? I wonder if those headlamp housings are not as deep as the ones for the HIDs? If not, that may have an impact on one of our members who plans to install HID lenses and burners in standard housings...

Cheers,

Don

 

The car has performed flawlessly with regard to electrical operation, so I am feeling confident the loose ground connection was indeed the problem.

Today I purchased zinc plated standard steel replacement bolts along with zinc plated steel nuts to replace the SS ones. I could not find aluminum bolts anywhere. I DID however find aluminum washers. The aluminum washers will be in direct contact with the frame on either side of the hole.

Zinc is a sacrificial metal so I expect the bolts and washers to corrode first, and then hopefully the un-coated aluminum washers will take the bulk of the damage following that. I will keep a close eye on things over the next couple of years and if I see any corrosion beginning in the vehicle frame I will immediately come up with a different plan.

If there is any glaring flaw in my current plan please feel free to educate me, otherwise...thanks for all the input and advice.

Jeff

 

Jeff,

I think you should be fine based on what we've read in that document about galvanic corrosion, but I would recommend that you check the stud and parts again next spring after the car has been through winter, especially if they use road salt or brine in your area, since galvanic corrosion occurs "in the presence of an electrolyte," such as saltwater, acid rain, and various salt solutions that can form as humidity and moisture attack common metals found in automotive alloys, like magnesium, copper and iron.

And if you think of it, please report back to let us know how things are holding up.

Cheers,

Don

 

************ LIFETIME SOLUTION! **************************

The best solution to solve this problem is NOT to repace the original screws or nuts with steel or aluminium. The solution I prefere on my X358 is to use a strong isolated extension cable copper 10mm² . Mount the other end at a dry place. I used one of the two M10 screws of the upper stabilizer.
This location is always dry, so no oxidation/corrosion will occure. For the other end use a messing screw and nut (size M8) and put all four cable ends together (G1 and G2 grounding points). Let this end hang in the air.
Regards Thomas Kaltenstadler. FYI: Data Recovery in Germany is my profession.
************ LIFETIME SOLUTION END :-) ********************

 

I would strongly recommend, to prevent corrosion and oxidation in all ground connections, is to use Gardner Bender OX-Guard. It is specifically designed for use with aluminum, and the electrolysis that happens between dissimilar metals like copper and steel. However, never use this product in snap together electrical connectors, like body harness or sensors, since it is conductive.

 

Hi Thokal,

Welcome to the Jaguar Forums. It's great to have you with us.

The ground points behind the headlamps are well protected from rain, car wash water and road splash by the hood, upper radiator cover and lower splash guard. Humidity is probably the real culprit in corroding the ground studs, terminals and nuts. In our area the average humidity is 84% in the morning and 54% in the afternoon, so no part of the car that is exposed to ambient air is ever truly dry.

While we're on this topic, it's worth a reminder that the torque specification for the ground stud nuts is just 6.5 ft. lbs./9 Nm, or just a little more than hand tight.

When you get a chance, please visit the New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and post an introduction so we can learn something about you and your Jaguar and give you a proper introduction.

Cheers,

Don

 

Dear Don, nice to meet you.
I want to give you a more detailed answer.
You are right at your location, but in Germany we drive much faster than 55mph. So if it rains a lot or you are driving very fast during rain or in winter when salt ist used to keep the roads free from snow and ice this location near the head lamps is wet not dry! So galvanic corrosion happens and the aluminium bolt will be destroyed during this process. Normal humidity will not result to this problem. BTW: A bad grounding of G2 (this is the lower grounding pin) may result in bad canbus signals and disturb the hole ecu. On my car motor stopped after turning on the wipers!!!!
The wiper electronic was ok but in combination with the bad signals from DSC the ECU could not work proberly resulting in engine stop.

The corrosion of G2 is the same as putting an resistor between ground of DSC and ground pin G2. So the ground potiential of DSC will not be zero voltage and ECU will not see a correct low signal from DSC-Modul. This effect is called ground bouncing!

!!!!
So my conclusion is: Always check G2 ground Pin at first if any DSC or ABS messages occure in display! And to get rid of this problem use my solution mentioned above.
!!!

 

Hi Thokal,

Thank you for your expanded explanation, but I'm still not certain I can agree with your reasoning. Galvanic corrosion occurs between two dissimilar metals in the presence of an electrolyte. Your use of a copper extension cable to connect the aluminum ground wire terminals to the aluminum body of the car is likely to cause galvanic corrosion, not prevent it. The document at this link shows that aluminum and copper don't necessarily play well together:

https://www.fastenal.com/content/fed...0Corrosion.pdf

Since the original ground stud, wiring eyelet/ring terminals and nuts are all made of aluminum, it is not galvanic corrosion that causes the interruption of current flow. It is the formation of aluminum oxide, which occurs spontaneously whenever aluminum is in the presence of water and/or air, regardless of whether the water or water vapor contains sodium or any other electrolyte. Here's some information from a website dealing with corrosion of metals and the link to the site:

"Aluminum being the most abundant metal in the earth’s crust (at 8.2% of the total metals) is never found free in nature. Aluminum is reactive and will react spontaneously with water and/or air to form aluminum oxide. Aluminum oxide, Al2O3, forms a stable passive layer that protects aluminum from corrosion or further oxidation. This layer is about 4 nm thick and will provide corrosion protection as long as this oxide layer is stable."

The Oxidation of Aluminum


That's great information, and supports the idea that it only takes a very slight layer of aluminum oxide to cause problems. The natural layer that forms is just 4 nanometers thin, so owners who have visually examined their ground studs, nuts and terminals and determined that "they look clean" are failing to grasp how little corrosion it takes to inhibit the flow of electrical current. The aluminum oxide is a very thin, whitish layer that may only be visible on very close examination.

I am anxious to hear more about your knowledge of the Mechatronic. We've had plenty of questions about it, so when you come across threads on the ZF 6HP26 please contribute! Also, please don't forget to post an introduction in the New Members Area at the link I posted earlier. Posting an introduction is a requirement of the forum.

Cheers,

Don

 

So after accidentally breaking off our studs... (They were pretty badly weakened by corrosion) I removed the headlights, Drilled out the studs ground off the paint and made a smooth clean surface. I over sized the holes a little. They I used aluminum washers I made from aluminum bar stock. I put the aluminum washers on both sides of the hole. Inserted a stainless steel bolt which does not contact the actual car frame. Then I torqued the heck out of the bolts from both sides to sandwich the aluminum washers really tight against the clean metal. (deoxit of course) Then I put on the wires...
logic? The bolts will corrode the aluminum but not my frame. The home made aluminum washers will fail first and since I over sized the hole my bolt is not in direct contact with the car. I can replace the aluminum sacrificial washers when ever I want. Then I painted the whole thing.
not permanent but easily repaired next time.