Important Grounding Points

[TomoHawk]

If having good grounding connections is so important, can anyone give a list of which ones, and about where are they located?

Such as

Headlights

Taillights

Instrument lights

Engine

Any others?

thx

[TomoHawk]

Now that I'm thinking about ground connections, how would you test them to see how good they are? Would you go with the restance accross the ground point? How would you test the ground connection for something like the headlights, or the gauge lights (highest on my wiring l'debug' list).

thx

[hls30.com]

Measuring the voltage drop across them is a quick way with a VOM. Measure from the negative terminal of the battery to the block, then to the chassis, then from the chassis to the block, then from the chassis to what ever connection you want to check. anything more than 0 means there is something happening, anything more than .5v means you should take care of the connection before it causes you grief!

Follow the FSM diagram and measure across the ground before and after switches, plugs, and the driven item.

WIll

[TomoHawk]

You mean 21/2 Ohm, Not 1/2 volt? If you're getting voltage from the battery Neg. terminal to the chassis, you definitely have a problem.

thx

[hls30.com]

No, I ment voltage-well actually voltage drop. 1/2 a volt drop is usually the beginning of a problem, I would still fix that problem, but if you have that, you probably have more, and the largest voltage drop is the one to fix first.

If you have a 2&1/2 ohm problem across a ground, you are probably going to have smoke or something that doesn't work at all help you find the problem! An approximately 5amp difference (approximately 12v/2.5ohms) across a ground is not a good thing!

Will

[TomoHawk]

I saw a show from Two Guys Garage where they were checking the cables on the starter & battery, and what they did was to measure with a digital voltmeter, using the lowest volts range, the difference in millivolts across a connection. Then they determined that one of the cable ends was bad with too much voltage drop, so they replaced it.

My intent is to find & check grounding points to see where I can improve the electrical system, especially lights, but I think it would help the ignition system and fuel pump too.

I just need to find out where the ground points are on the chassis & engine. Black wires?

thx

[loy]

i think there are a couple in the engine bay. Theres one behind the licenes plate. Others i don't know off the top of my head.

[Ed]

Not only would making sure you have good grounding point important but also the connections on ALL your harness connectors. These cars are over 30 years old and many of us suffer from the headlights dimming when the car is at idle. I was led to believe for a long time that it was a factory defect. But once I cleaned all the ground locations and the harness connectors I get NO visible decrease in headlight illumination. So my two cents tell me to tell you clean all your headlight, parking light, ignition, and charging connectors. You will notice a difference.

[TomoHawk]

Well, mine is only 27 years old now, but I'm constantly cleaning connectors & pins. I don't really have any problems with the headlights being dim- they are pretty bright at any engine RPM. The only connectors I haven't gotten to are the ones on the lamps themselves and the ones buried high behind the dash.

But it helps to know where the grounding points are under the hood & on the chassis (in the back.) The wiring diagram only shows where the ground tails are on the harness.

thx

[loy]

i think theres one By the battery near the frame rail

[TomoHawk]

take a read of this document on cleaning the electrical connectors on a Z.

It's mainly about the techniques, but it shows the location of many of the important engine connectors and a few grounding spots on a fuel-injected Z engine.

Still need to find the chassis & wiring harness grounds.

http://www.atlanticz.ca/zclub/techtips/electricalconnections/index.html

[TomoHawk]

Since some asked this about a 240Z, I'll ask it about a 280Z.

Where is the ground for the taillights, fuel level sender, or fuel pump?

thx