Ground

[USMC_Turbo6]

What's the best place to ground the car. Do I need to extend any wires to do it?

 

[Lil Truck]

The negative battery cable connects to the front of the block, passenger side bottom bolt of the turbo mounting bracket. The connection needs to be clean and free of paint and rust.
the rest of the ground connections are listed in the link below...... the need to be inspected cleaned and replaced if necessary. Upgrades are heavy gauge wire with solid connections!!!

http://www.gnttype.org/techarea/electrical/grounds.html

 

[Lil Truck]

What's the best place to ground the car. Do I need to extend any wires to do it?

Caspers sells a ground upgrade kit for our cars.

 

[USMC_Turbo6]

Thanks

 

[Nick Micale]

What's the best place to ground the car. ........

You are NOT grounding the "car", you are grounding each electrical component or sensor.

For each circuit the ground path must return to the battery with the same gauge wire as being used for supplying power to the component for optimum performance or function.

The engine is a ok ground plane, or terminal, as the negative battery cable is connected there and this solid piece of cast iron is a relatively good conductor.

The body on a GN is used as a ground for non-critical items like lights, horn and accessory items. Ever wonder why the Scanmaster displays voltage .2-.3v less than at the battery or alternator? Because it is grounded to the body.

The worst ground "item" I see is the fuel pump grounded to the frame? The factory never used the frame for any ground as it is made up of many pieces that are riveted together and the low grade steel is a very poor connector compared to a stranded copper wire, especially after years of weather, rust and corrosion.

Yes, many GN's owners use the frame for a ground, but when you are modifying or upgrading performance, every component must work as designed, and be provided with compatible power/ground circuit.

Casper's ground kit is not an "upgrade", it is just a more accessible location for a ground wire, it is a secondary terminal for the ground path return to the battery rather that using factory location at the back of the head.

On the 1989 TTA, the factory relocated the 4 harness ground wires to a more accessible location on a studded intake manifold bolt.

 

[TurboTdr3.8]

I like using the the battery ground post when I can as that is where the power source is .

 

[mikestertwo]

What's the best place to ground the car. Do I need to extend any wires to do it?

The grounds should stay where the factory put them. There is a reason they are located where they are especially the ones on the back of the head. Those grounds are signal grounds for the sensors on the motor. Those signals have to go back to the computer not the battery. I have seen guys move those grounds to the battery with negative (no pun intended ) results. It put an offset in the sensor readings. Like Nick said, just make sure all the grounds are clean and tight.

 

[GNRick]

The body on a GN is used as a ground for non-critical items like lights, horn and accessory items. Ever wonder why the Scanmaster displays voltage .2-.3v less than at the battery or alternator? Because it is grounded to the body.

I read on the board that sometimes voltage is lost through the connection at the ignition switch located down on the steering column. Is this not true? Also, I bought an led voltage gauge (made in China) that has three wires- red for power, black for ground, and yellow for signal. I get the power from the fuse box, ground from the body, and signal direct from the battery. The led gauge reads .2 - .3 volts higher than my pillar mounted VDO volts gauge which just gets its signal from the fuse box.

 

[Nick Micale]

The grounds should stay where the factory put them. There is a reason they are located where they are especially the ones on the back of the head. Those grounds are signal grounds for the sensors on the motor. Those signals have to go back to the computer not the battery. I have seen guys move those grounds to the battery with negative (no pun intended ) results. It put an offset in the sensor readings. Like Nick said, just make sure all the grounds are clean and tight.

Your post is a little confusing as I do understand some grounds signals do emanate from the computer to complete a circuit, but their ultimate destination must be back to the battery?

As far as the grounds located on the back of the head vs. a few inches forward on the head with an intake bolt will make them more visible and accessible w/o any affect on their function.

 

[mikestertwo]

Your post is a little confusing as I do understand some grounds signals do emanate from the computer to complete a circuit, but their ultimate destination must be back to the battery?

As far as the grounds located on the back of the head vs. a few inches forward on the head with an intake bolt will make them more visible and accessible w/o any affect on their function.

Nick, I didn't mean to confuse anyone. Moving the grounds a few inches on the engine doesn't make any difference as long as they are on the engine. I moved mine to a manifold stud near the back of the motor. The point is those grounds have to be located on the motor rather than going back to the battery. The reason is if you move those grounds to the battery the only way the return signal from the sensors on the motor can get back to the computer is through the negative battery cable bolted to the engine. If any other accessory is running (and there always is) this produces a current in the battery ground cable which will offset the signal grounds from the sensors. This is why there is also a ground wire from the computer to the engine block. Case in point....I had a customer who was complaining the motor was running rich yet the O2's looked normal. I found he had pulled the grounds off of the back of the head and tied them directly to the battery thinking this was better since that's where the power comes from. What this did was put an offset in the O2 reading the computer was seeing so the computer compensated. I moved the grounds back to the motor and problem solved. Most people don't understand the difference between power grounds and signal grounds. The computer relies on accurate data from the engine sensors. It can't do this if there are extraneous currents going through the grounds to the sensors caused by other components.

 

[Nick Micale]

Nick, I didn't mean to confuse anyone. Moving the grounds a few inches on the engine doesn't make any difference as long as they are on the engine......................

Very good post and info, and certainly no confusion there now, thanks!