electrical problems with guages

[99LS1]

The coolant temp. guage never worked in the 73 mach, so I decided to update it with new guages (along with the oil pressure/volt. guage) while troubleshooting the problem

With a new sending unit the guage doesn't read, it just bounces below 100; even with the car warm. To test the wiring I ran a new line directly to the sending unit, didn't fix it.

The oil pressure guage is now acting the same way. It bounces around way too much to work right. Before the guage swap it too was working.

The alternator guage is working right and has always worked.


Any thoughts? I only have a schematic out of a haynes manual and I'm having problems understanding it. Wiring is not something I understand very well.

[QWKSNKE]

Have you checked all your grounds?

[Wall96cobra]

Make sure the engine is grounded to the firewall, should be a braided strap.

[LeeH]

The ga. will have a flat ceramic resistor between the posts on the back, I bet the resistors are bad. I will look through and see what the resistances are for your gauges, You can then go to Ratshack and get some to repair them.

[99LS1]

Good grief, there was no chasis/engine ground. I put one on, fixed the problem.

[Wall96cobra]

Good grief, there was no chasis/engine ground. I put one on, fixed the problem.



Yeah that's pretty common in the older cars, someone down the line usually forgets about putting it back on. Glad you found it.