Late Griffith 500 Earth points...

[briantvr350i]

Hi all,

Looking to trace an earth fault which is bothering the instruments in the dash...

I've run a separate earth from the "bunch" in the dash wiring loom direct to the battery, which has gone some way to solving the problem, but not solved it completely. So now I intend working around as many of the earth points as I can...

These are the ones I know of...

2 earth points under the front end of the whale tail, in the vicinity of the door release handles.

1 under the drivers side wheel arch (goes from engine to chassis IIRC)..

1 behind the petrol tank where the body is bolted to the chassis.. (can anyone confirm which side bolt this is?)

1 behind the radiator grill where the body bolts to the chassis.. (again can anyone specify which side bolt is used?)

Are there anymore? Any more engine to chassis links? my old wedge had one underneath at the side of the gearbox.

Regards,

Brian and a Green Griffith 500

[lancelin]

This cold be a useful topic. A diagram showing the locations would be great. Many TVR running issues are associated with bad earth and even earth loops!

[phazed]

My 95 chim had a gearbox to chassis earth.

Also should be one from offside front outrigger to engine.

[Hedgehopper]

This is the earth at the front of the car, it's on the lower o/s chassis rail.

[v12.24v]

Mine has also an ground point on the backside from the left cylinder head. But it is an 94 lhd. You can See it with an good light, but you can reach it only with dismounted exhaust.

[phazed]

That is correct. I think they will have an earth from the nearside head at the rear.

[Sardonicus]

The grounds on the N/S cylinder head are all ECU related IIRC

[Steve_D]

EARTH POINTS
E1 = O/S Front of Chassis.
E2 = Engine Timing Cover. below alternator near oil pressure senders
E3 = O/S Chassis Outrigger Strut.
E4 = Rear of N/S Cylinder Head.
E5 = N/S Tunnel Top.
E6 = O/S Tunnel Top.
E7 = N/S Rear of Chassis Hidden behind fuel tank.

E3 is the main engine to chassis earth.
E2 is primarily the ECU earths
E4 is Lambda sensor earths and one from ECU

Steve

[briantvr350i]

Thanks for all the replies boys...

Update on progress...

Swapped out link under drivers wheel arch, this didn't change anything...

Started work and removed whale tail..

Drivers side bolt, cleaned up nice and shiny, cleared the threads out in the chassis with a tap.. new bolt... this shows slight improvement..

Passenger side bolt, can't get it out while dash in in...

Measured up and obtained a replacement main battery earth (which connects to the bolt you cant extract) long enough to reach to the drivers side bolt... Installed that... Result... struggled to see the resistance on meter now and no change when ignition turned on..

1 thing left to do, using the "old" main battery lead, provide a link between the two dashboard bolts...

Conclusion...

When I went to have the new lead made up I asked what size of cable to use.. Specialist Auto Electrical opinion, 25 mm2 or 35 mm2 cable... (went for 35 mm2) TVR had used 16 mm2...

I wonder if this has anything to do with the "hot start" issues that have prompted a variety of "fixes", should we now add, "upgrade the main battery earth" as another one of them...

Regards,

Brian and a Green Griffith 500

[Hedgehopper]

There are a variety of Hot Start issues. My particular problem was that after, say stopping to refuel, the starter would crank but too slowly to restart the engine. This indicated that there was no problem with the starter or its solenoid, just a lack of power getting there.
I changed the TVR negative and positive cables for 40mm ones and the problem was immediately solved. At the same time I also ran a negative cable from the o/s chassis outrigger earth point direct to one of the two starter motor fixing bolts.

[Sardonicus]

Waste of time using ohms test for high voltage circuit far more reliable results measuring for voltage drop in said circuit

[Penelope Stopit]

Ohm y god, such an easy mistake to make if not knowing better

As above, it's all about the VD when under cranking load