instrument cluster ground

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RedFish said:
A daisy chain of parts and hardware isn't a conductor when compared to an actual copper wire. For that reason, If a wire was attached at only 1 screw that grounds a bulb socket, that bulb wiil glow a little brighter or a lot brighter than all others. A ground wire added at the headlight switch is a fairly level/equal ground when are the parts are new or renewed.
Click to expand...

True, but RedFish, aren't we approaching the realm of the theoretical here? Wouldn't the conductivity from one end to the other of the pot metal cluster housing, compared to the same length of copper wire, or silver or gold wire be too small to measure?. When I put one lead from my Amprobe DVM at each end of my cluster housing, it reads .04 Ohm. When I short the two meter leads together, it shows .04 ohm.

Perhaps it would be "better" to attach the ground wire to a screw that does not provide ground to one of the bulbs, maybe one that mounts the speedometer, or drill and tap a new grounding point somewhere away from any of the bulbs. I might be wrong, but any ground is better than NO ground. Debating the best point on the cluster chassis to attach the ground wire is like debating how many angels can dance on the head of a pin, isn't it?

ATB

BC
 
The factory engineers added the single ground at the headlight switch which is the same result as speedo. The problem is over time the screws loose their connection to the copper pad and to the pot metal threads so the total resistance accumulates and varries from one point to another. A tinned ring terminal against the copper pad is taking a more secure , direct, dependable path. Soldering the wire to the copper trace would be optimal only if vibration and the yank factor were eliminated.
Not so much electrical theory or proof from a ohm meter, just attempting to improve upon the next 45 years service while renewing.
A lot of ground wires that aren't routed in a proper manner might repeatedly break the plastic bulb sockets when yanked too so... Who knows whats the best plan.
 
RedFish said:
The factory engineers added the single ground at the headlight switch which is the same result as speedo. The problem is over time the screws loose their connection to the copper pad and to the pot metal threads so the total resistance accumulates and varries from one point to another. A tinned ring terminal against the copper pad is taking a more secure , direct, dependable path. Soldering the wire to the copper trace would be optimal only if vibration and the yank factor were eliminated.
Not so much electrical theory or proof from a ohm meter, just attempting to improve upon the next 45 years service while renewing.
A lot of ground wires that aren't routed in a proper manner might repeatedly break the plastic bulb sockets when yanked too so... Who knows whats the best plan.
Click to expand...

It almost seems like we're barking up different sides of the same tree (and I'm pretty sure that's the most mixed metaphor that I've ever posted).

Since the pot metal chassis of the cluster is the common ground point for all the lights and anything else that draws power from the cluster positive (hot) it seems to me that soldering to the metal of the chassis would be the ideal, but soldering to pot metal is mighty difficult.

The point of the ohm meter reading was to show that the resistance of the cluster chassis is low enough that it makes no practical difference exactly where the ground wire we're adding is connected. Wherever we put it, the connection should be as low resistance as possible.

What I have been doing is just a ring terminal under the head of any screw that threads into the cluster chassis. I might sand the chassis and add an internal tooth lock washer and some grease to improve the connection, but any improvement would be very small. The treatment of the other end of the new ground wire should be similar and its routing and length need to be thought out to avoid problems down the road.

ATB

BC
 
The ground is right after the bulb, exactly oposite the positive. The current could leave the same way it arrived if desired. The factory used what compares to a flashlight in circuitry. Beating on a flashlight works for me. I dont want to beat on the dash.
I'm not barking though. I really really dont care. Unsubscribed
 
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