Chevrolet Repair: Electrical and Transmission, chevy venture, running in circles

Question
So this ground wire can effect my transmission along with the instrument panel? I haven't checked yet, but I certainly will.

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Followup To
Question -
I have a 1999 Chevy Venture and recently when I use the turn signal some of the other instrument lights start coming on. The first time the air bag light was flashing, then another time the ABS and brake lights came on and the air bag light flashed too. It doesn't happen all of the time but it has been more frequent.
Also, sometimes my transmission has a hard shift. If I shut the vehicle off for a few minutes and then start it back up it will shift normal. This is also an intermittent issue.
Answer -
I would look for a loose ground wire somewhere.
Under the dash, or possibly even from the engine to the firewall.
Van

Answer
Hello Janice,
A loose or missing ground wire can have you running in circles for days.
Everything electric depends on a complete circuit.
The best circuit is from power switching device, through the controlled item, and directly back to the battery through a good ground.
Every electron that passes through the positive cable or wire....every single one...must return to the battery through a ground.
Ground circuitry must be every bit as good as the power wire circuitry.

Here is the rub...

If you have a light bulb that recieves good power, but the ground is loose where the socket connects to a housing, for example, and there is another light circuit in the same housing that uses a mutual ground connection...and remember, I said it was a bad ground connection....then the power can go through one bulb, through the mutual ground wire that is not grounding, and back through the other bulb,(that you are not trying to use), and back through that bulbs control system to reach a ground somewhere else.
Both bulbs will light, although not necessarily with the intensity expected, and other things could happen, such as turn indicators iluminating, cruise disengaging, ABS light blinking.....you name it....just strange things happening.

Kinda like when you see someone turn on a turn signal, and the tail lights blink dimly, etc.

The dash is the same way, as well as electronic controls in the transmission, engine, and other components.

A bad or missing ground can just cause unexpected things to happen.

Now...if you happen to live where they salt roads in the winter....those ground problems can be worse.

As for the firewall ground I mentioned....remember, the engine and transmission are mounted on RUBBER motormounts, not for electrical insulation, but for noise and vibration insulation.
With all the electrical components on both engine and body, it is imperitive that all orriginal grounds be in place, and in good shape.
That firewall one is just one that seems to be routinely discarded when work is done in that area.
But I have seen them actually melted in two, possibly when someone connected a jumper cable to a frame part when jump starting a vehicle, and pulled more power than the body ground wire could carry.

Also, under your dash, probably above the parking brake lever, there is a little block with 6 or 8 or more wires connected to it,all black wires usually, and one running to ground. Make sure they are all tight and good connections, especially the one running to the body. Remove it a scrape the paint off is a great thing to do.
Same under the hood. Find all ground wires, and make sure they are clean and tight.

Then there is the possibility of the connector on the back side of the instrument cluster itself. All the connections need to be clean and making good contact....but it is normally a problem with ground integrity that causes strange things like you have.

Van