Fiber optic cable on gauge cluster?

[morglan]

I swapped gauge clusters last night on my 82 K10, and the oil pressure gauge and water temp gauge read all the way to the left (high). After some research, I found that it could be due to a faulty ground. I looked around, and found a black wire with an old male end still attached coming off the top left corner of the cluster (which had apparrently broken off my old cluster, because there wasn't one there.)

Assuming this was the ground wire, I cut off the old male connector and stripped the end, and found what appears to be a fiber optic cable--what is this?

ALso, am I correct in assuming that my gauge trouble is probably due to a missing grounding? (The amp-meter works, and the water temp gauge worked on the old cluster, but the oil pressure gauge didn't.)

Thanks!

[88Jimmy4x4]

Not sure what your gauge problem is, but that fiber optic cable goes from a gauge bulb over to your ashtray and thats what illuminates it. If you ruined it, just discard it and live without it.

[87 STEPPER]

The fiber optic cable is for the ash tray light.

You may have a bad ground or if the new cluster is from a truck with a differant size Eng. you may need to change the sending unit to match the guage.

[morglan]

Thanks for the fiber optic answer! 87 Stepper, probably a dumb q, but is there a sending unit for the water temp? (If so, wouldn't that be the same size no matter what the engine size?)

[87 STEPPER]

Well......H20 temp. senders have differant resistance values.

And a 4 or 6 cyl. eng. may use a differant sensor than a V8 but the physical size will be the same.

Your problem sound's like a sensor problem due to the fact the guage is working that proves theres a ground present so if the sensor is not the correct one you may be reading high or low in your case it's high.

[TIMSPEED]

I think that's my problem aswell. I don't have a correct sending unit, because it never reads any hotter than ¼ mark! Even with the cooling fan not even there!