My Gauges are not accurate

[SlyMart]

Since I got my car on June 5th 2015 which it's a 1978 Corvette with the L82 and automatic some of my gauges are not accurate.

The cluster speed is not accurate.. it's like 15 - 20 km behind.. I need to go at least 100 km on my cluster to run at 80km

The tach is also not accurate.. when the car is completlely stopped it will be at 0 - 5 rpm

And my gas gauge wobbles like a bobble head and it's not near accurate..

Could it be a ground issue or I need to replace some parts..???

 

[wildone909]

Since I got my car on June 5th 2015 which it's a 1978 Corvette with the L82 and automatic some of my gauges are not accurate.

The cluster speed is not accurate.. it's like 15 - 20 km behind.. I need to go at least 100 km on my cluster to run at 80km

The tach is also not accurate.. when the car is completlely stopped it will be at 0 - 5 rpm

And my gas gauge wobbles like a bobble head and it's not near accurate..

Could it be a ground issue or I need to replace some parts..???

Hey Sly.... The speedo is mechanical so no wiring problem there, The tach may have to have the needle re set so it starts at 0 rpm ,you pull the needle off and turn the key on then replace the needle at zero rpm{ more info on the net} the gas guage may have to be replaced if it bounces while driving..(the gauge has a built in buffer so when the fuel sloshes the gauge doesn't bounce) A good way to check the electronic gauges for a ground problem is turning on the dash lights.... if the gauges read differently with the lights on or off you have a power or ground problem. good luck.

 

[Keith Tedford]

If all the gauges are doing strange things, you could have a grounding problem somewhere. I have no love for electrical systems.

 

[SlyMart]

thanks for all your help I will try your advice especially wildone909. Thank you

 

[SlyMart]

I found the problem with my fuel gauge which I posted it another topic which it was a previous owner that was too cheap to replace the defective paper circuit board.

 

[SlyMart]

Got a few goodies on July 28th that I ordered from Eckler's. Last week I got a brand new fuel gauge and a new printed circuit board. Today I got a brand new center gauge console, a brand new clock.. warning plastic lens for GEN Low fuel, seat belts. Front and rear factory speaker harness since the previous owner cut it.. and a brand new plastic lens that covers the gauges..

 

[SlyMart]

Finally put the new center console back together last weekend, Replaced all light bulbs, Replaced the printed circuit board, Replaced the clock, Replaced the gas gauge, Replaced console lens, Replaced the whole console with a new one, Replaced both warning labels. and the gas gauge and clock now works.. yay

 

[nascar03]

SM..
That new centre gauge cluster looks great.
Well done.
Hopefully this fixes all your electrical gremlins.

graham

 

[Brian Keery]

When you start your car, does the LOW FUEL and GEN light both light up, or just the GEN?

 

[SlyMart]

The low fuel light doesn't come one when you turn the ignition to on.. Just the Gen..

 

[SlyMart]

Ok last summer I was having issues with my speed cluster being not accurate and I was saying that there is a possibility that the previous owner before him might have upgraded the differential to a 3:70 from a 3:55. As I was working on my car today and I was removing the rear spring I realized that the rear end was never touched. The rear spring kinda fell apart and the bolts were all factory originals which they were in bad shape. So is there a possibility that a transmission kit or some sort of work have been done on the transmission to have the speed cluster out of accuracy?

 

[SlyMart]

ok I just found out that my rear end is a 3:55 gear and now I need to know why my cluster is 10km over.. so maybe the tranny (TH350) got some upgrades and it's causing the problem..

 

[nascar03]

Tire size??

Graham

 

[SlyMart]

I am pretty sure that they are the sock ones.. the 60 series. But I will confirm after work

 

[SlyMart]

I should of uploaded this picture at the beginning of this post.

 

[nascar03]

Hey Sly..
That rpm vs speed in the photo is not right!
Are you still in second gear??
Do you have another tach(or borrow) that you can connect to your car to verify rpm?
Also run side-by-side with a newer car with digital speedo to verify speed.
Graham