NO TEMP (check this search)

[kgillyk5]

My 90' K5 temp gauge no worky...found this quote below from a search. This was based on an 86'...I think this would apply to my 90' as well but looking for confirmation. Thanks.

OK, here's what I learned today. As the engine coolant temp rises, the temp gauge sending unit applies resistance to ground . The resistance causes the temp gauge needle to move on the scale. More heat equals more resistance to ground applied by the sending unit which causes the gauge needle to move further. At some point when the heat gets excessive the sending unit applies full ground to the lead which in turn causes the temp gauge needle to peg at or past 260.

Yes, you can test the gauge by recreating the above scenario. Take the lead off the sending unit, turn key on, have someone watch the dash mounted temp gauge, and touch the lead to an engine ground. The gauge needle should peg. If so, the gauge apparently is OK.

 

[4X4HIGH]

Yes, that is correct. GM uses grounds to activate items.

 

[tx_sub]

My guage wasn't reading right. I replaced the temp sending unit in the driver side head and fixed it right up. It has a different plug than the one in the manifold. My vehicle is a 91 sub.