Dash mounted switch grounding?

[bronco italiano]

Are the switches (lights/flashers/wiper/ignition grounded via the metal dash?
My buddy wants his dash powder-coated and I don't want to powder-coat the under-dash (using a dash overlay) portion if the switches rely on the dash for grounding.
I could always grind away a small section of the powder-coat but any moisture risks corrosion.

 

[DirtDonk]

Yes, and no.
The ignition switch grounds to the dash, but the only function of that is to illuminate the brake warning lamp.
None of the other switches need a ground, because they are simple, pass-through switches.
The primary beneficiary of a grounded dash is the instrument cluster.

You can still powder coat, and do what you suggest and grind a bare spot.
Once you attach any grounds to it, put a spritz of paint over it.
With a well applied powder coat (note that I say “well applied“ in that regard) any rust should not be a problem in your lifetime.
Even surface rust would be minimized, and probably eliminated with a spritz of paint over the ground point.
You could make that permanent too, by mounting a ground stud or block, grounding that to this bare spot, painting over the bare spot and ground connection, then attach any future grounds needed to the grounding block or stud.

It’s doable.
Do you live in a an extremely rust prone area?

 

[904Bronco]

I have powder coated one dash with success, I did add grounds to the instrument cluster, Aux power ports, and Cig lighter. I am guessing some of the minor filing I had to do to the holes probably opened up grounding methods, but as Paul has stated most switches are pass throughs...

 

[ba123]

if you have to grind, just put a little dielectric grease and all good. That'll keep the corrosion out and all I would do if a ground is needed.

 

[bronco italiano]

if you have to grind, just put a little dielectric grease and all good. That'll keep the corrosion out and all I would do if a ground is needed.

Oh yes. I am a nut with the electrical contact grease!!!
My Uncle was a 20 year USN sonar/electronics Chief and he would use Vaseline to protect the electrical from corrosion.

 

[Torkman66]

Gents, done this many times. Here is the best way that I have found. Works great. Assuming you have not yet powder coated the dash, prepare a nice spot on back of dash down to metal and then attach a copper grounding bar. Get one about 2 inches long about 3/8” wide. Attach it so screws pass through inconspicuous location. Then tell you PC guy to tape over the grounding bar. Just the top edge of the bar where the 4 or five grounding screws are. Have them powder coat everything including up the sides of the grounding bar but not the top where grounding wires will attach. Use that for all your grounding needs. HOWEVER, if you PC the dash then the attaching bolts may not actually ground the dash where of course the grounding bar is located. Whether I PC dash or paint it, I ALWAYS run a ground from engine ground thru firewall to back of dash. That provides great ground for all your grounding dash needs. No such thing as too many grounds…ok, maybe.

 

[Steve83]

A better solution is to simply NOT use grounds - use return wires that go back to the B- post, or that connect to cables that already go there at other larger ground bolts (like the frame or block ground bolts).

 

[bronco italiano]

I ended up buying a ground bus and will mount on the firewall/ run all interior grounds to the buss, then the large lug will have a cable to the frame where the engine strap is at. Thank you all for the guidance/assistance.

 

[Torkman66]

Good call! Consider adding your own grounding system. Run ground from battery down to one of the bolts mounting the starter. Starter pulls greatest amps and having ground inches away from hot at starter is excellent in terms of ohms drop. I also run a ground strap from block to the frame, 10 Gauge from front frame where engine ground strap mounts to the rear of body by fuel tank, another from frame to alternator mounting bolt, from frame to front grill, and from frame to behind dash. Never had a single grounding problem and all components work as intended.

 

[jamesroney]

Good call! Consider adding your own grounding system. Run ground from battery down to one of the bolts mounting the starter. Starter pulls greatest amps and having ground inches away from hot at starter is excellent in terms of ohms drop. I also run a ground strap from block to the frame, 10 Gauge from front frame where engine ground strap mounts to the rear of body by fuel tank, another from frame to alternator mounting bolt, from frame to front grill, and from frame to behind dash. Never had a single grounding problem and all components work as intended.

Interesting. I have never attached a ground to the frame. The only factory circuit that grounds thru the frame is the rear fuel tank sender and the brake imbalance lamp. The frame carry’s no other current. Whenever I put an electric fuel pump in the tank, I run the ground to the body.

The dash carrys current for the ground on the brake lamp test circuit, the dash lights, and the instrument voltage regulator. So the gage cluster needs to be grounded. This is typically done with a single star washer under one attaching screw to the dash, and the dash grounds to the body. Otherwise the courtesy light, cigar lighter and the radio won’t work.

 

[Torkman66]

Agree, in most cases, simple stock grounding will work fine. But I have responded to dozens of threads on multiple car and truck forums where folks were having electrical issues. Lights, gauges, sporadic behavior, even buzzing in radio. In at least half of those cases it was a ground problem.

About 25 years ago and at least 10 restorations back, I started building a simple ground system into every resto. Run battery ground to starter mounting bolt and then from that bolt run 10 gauge back, up, and forward. Easy to do and I’ve found all electrical works well.
Likely overkill, but easy especially when body off.

 

[Madgyver]

run a seperate ground lead.

 

[bronco italiano]

"Mad", Thank you for the inspiration to try this "Mad-mod"!!!
I really like how it is going to turn out.