Bonnet earthing

chrisvine · Post by **chrisvine** » Wed Dec 11, 2013 12:00 am

I'm just adding the bonnet wiring loom but I'm not sure how it should be earthed. There is an eyelet earth connection, approx. 10" from the bonnet mounted junction 'box', where should this be connected?

I've seen some where it is attached to the triangular 8-pin bracket but I don't think this will give a good earth connection.

Also, on the other side of the bonnet, what is the correct earthing for the lighting. There's only one earth terminal in the 5-pin socket (which I think should be connected to the headlight). How are the side light/indicator earthed? Does it use the bonnet as Ground?

ChrisC · Post by **ChrisC** » Wed Dec 11, 2013 12:21 pm

From memory and I stand to be corrected... doesnt the 8 pin plug have a negative connection within it which will run to earth somewhere...

On my car there isn't another wiring connection between the car and the bonnet just that plug.

Post by **Heuer** » Wed Dec 11, 2013 1:25 pm

Eyelet should go to one of the two bolts in the headlamp area - it is a 'fail-safe' earth path. The 10 way connector has space for 4 earth connections (2x2) - one bullet from the 8 pin socket and space for 3 bullets to serve a) the loom b) side/indicator and c) head lights. On the other side you have a 5 way connector block. Loom earth goes to one side, jumper lead goes to separate double bullet connector to serve a) headlamp and b) side/indicators. The side/indicators are actually earthed through the housing but Jaguar put another 'fail safe' bullet connection on the casting. Dave Kerr sent me this picture:

The wiring is slightly wrong though as he has omitted the side/indicator fail-safe. In this picture the earth only supplies the headlamp harness and relies on the housing>bonnet earth. To be correct the headlamp earth bullet needs to be removed and connected to a double (2 way) bullet. You then need two black jumper bullet leads - one goes from the earth connector on the housing to the double bullet connector, the other goes from the double bullet connector to the 5 way.

Dave K · Post by **Dave K** » Wed Dec 11, 2013 4:52 pm

David,

On each of my side lights there is a eyelet for a bullet connector so I ran an earth from each one and put a double copper spade rivet into the cross member on the bonnet underpan on both sides.
I then ran the earth on the side nearest to the plug to a double connector into the main earth.
While not technically correct it is a belt and braces approach. You can't have enough earths I was told.

Dave

chrisvine · Post by **chrisvine** » Wed Dec 11, 2013 10:15 pm

Thanks all. I think I've worked it out now.

The bonnet loom has three earth wires:
1) for LHS lights, via the 5-way connector
2) for RHS lights
3) to the 'fail-safe' eyelet

I think a PO may have rearranged the wiring, using 2) as a jump lead to make the top two terminals earth and then plugged the LHS headlight and side/indicator directly into the connection block:

I'll use double bullet connectors on 2) and from the 5-way connector.

Thanks,
Chris

rossbraithwaite · Post by **rossbraithwaite** » Sun Apr 12, 2015 6:53 pm

How can this wiring be accessed on a complete car? Which panels need to be removed to investigate earthing in the bonnet? I have a headlight problem whereby my full beam lights work but dipped beam don't. I have established that the eyelet was not connected so have earthed this direct to the battery but the problem remains unchanged. Should that eliminate an earthling issue inside the bonnet?
Thanks,
Ross

chrisvine · Post by **chrisvine** » Sun Apr 12, 2015 10:10 pm

Ross,

The ten pin connector is mounted to the inside of the bonnet underpan. It's accessed by removing the LH headlight scoop.

The best thing to check is the wiring upstream if the 8-pin Bonnet plug. Are you getting 12v to the dipped beam wire (Blue/Red)? Worth checking fuse 2 if not.

rossbraithwaite · Post by **rossbraithwaite** » Mon Apr 13, 2015 7:30 am

Hi Chris,
Thanks for your response. I am pretty sure that I am getting 12v upstream of the 8 pin bonnet plug although found that it wouldn't light a test lamp. I think I traced this to very high resistance in the dipped beam switch which I have now replaced. I have checked by shorting out both the dipped beam switch and the headlamp switch. As the full beam lights work the only thing I haven't checked yet is continuity between the dip switch and the 8 pin plug. I have removed the LH headlight and all of its trim but the scoop is retained solidly. I assume this is likely to be stuck in place with mastic sealant so will take brute force and ignorance to remove?
Thanks,
Ross

chrisvine · Post by **chrisvine** » Mon Apr 13, 2015 2:50 pm

Hi Ross,

The sugar scoop is attached to the bonnet with rivets with a special head. The two chrome strips around the perimeter of the scoop snap onto these rivet heads. To access the 10-pin connector you need to drill out the rivets, so only advisable as a last resort once everything else has been checked.

The reason I thought it might be an issue with the supply rather than ground is because the headlights share a common earth. Therefore as your main beam is working it's unlikely to be the earth.

If you could get a multi-meter (negative lead connected to known good earth) to confirm voltage at 8-pin socket and then at the headlamp it might trace problem and whether it's within the bonnet loom.

Chris

rossbraithwaite · Post by **rossbraithwaite** » Mon Apr 13, 2015 4:01 pm

Hi Chris,
Thanks. Yes, I thought it might be a common earth and as removing the scoop seems like a big job I will revert to double checking the supply.
Thanks,
Ross

Link:
BBcode:
HTML:
	Hide post links

Link:
BBcode:
HTML:
	Hide post links

Link:
BBcode:
HTML:
	Hide post links

Link:
BBcode:
HTML:
	Hide post links

Link:
BBcode:
HTML:
	Hide post links

The 'E' Type Forum

Bonnet earthing

#1 Bonnet earthing

#2

#3

#4

#5

#6

#7

#8

#9

#10