electrical problems with guages

99LS1 · 12-29-2007, 03:10 PM

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 · 12-29-2007, 04:18 PM

Have you checked all your grounds?

Wall96cobra · 12-29-2007, 07:47 PM

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

LeeH · 12-29-2007, 09:51 PM

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 · 12-30-2007, 05:44 PM

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

Wall96cobra · 12-30-2007, 06:59 PM

Quote:

Originally Posted by 99LS1

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.

12-29-2007, 03:10 PM	#1
99LS1 WWIP Saving for Evo XXI Join Date: Dec 2004 Location: You like my biodata. B-i-o-d-a-t-a! Posts: 1,693	electrical problems with guages 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. __________________ 08 cbr 1000 73 mach 1

12-29-2007, 09:51 PM	#4
LeeH Senior Member Join Date: Dec 2005 Location: The conservative underground Posts: 341	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. __________________ 89LX Hatch 89LX Coupe 89GT 90GT 93GT

12-30-2007, 05:44 PM	#5
99LS1 WWIP Saving for Evo XXI Join Date: Dec 2004 Location: You like my biodata. B-i-o-d-a-t-a! Posts: 1,693	Good grief, there was no chasis/engine ground. I put one on, fixed the problem. __________________ 08 cbr 1000 73 mach 1

12-29-2007, 04:18 PM	#2
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Have you checked all your grounds?

12-29-2007, 07:47 PM	#3
Wall96cobra ooooo cake!!! Join Date: Dec 2004 Location: Saks, AL Posts: 1,630	Make sure the engine is grounded to the firewall, should be a braided strap.