Can someone please tell me where I can find the grounds for both the oil pressure and fuel gauges? Mine are still bouncing after I replaced the printed circuit.

 

The instrument panel ground is located on the left hinge pillar above the courtesy light.

That ground also serves the radio, anti-theft relay, courtesy lamp delay timer, vanity mirror, seat belt and key warning buzzer, wiper, heater illumination light, glove box light, cigar lighter and automatic transmission indicator light.

Just a curiosity question: does the fuel gage quit bouncing when you step on the brake pedal? If so, then you might also want to check the frame ground at the tail lights as it also grounds the fuel meter.

Also, what is the condition of the grounding strap between the frame and the birdcage? Ground strap (woven copper with no covering) is located on the driver's side by the #1 body mount.

 

Thanks mapman for the help, I found the grounds at the #1 body mount and I think the one for the fuel meter at the rear of the car, drivers side by the energy absorber for the bumper.

I unbolted them and used my dremal to clean the dirt and under coating off. The body mount ground had a little rust at both locations. I did not get to the ground at the left hinge piller, it got to late. by the way is that located behind the kick panel?

The fuel gauge does bounce when the break is applied and the woven ground strap appears to be in good condition.:

Thanks. cheers:

 

Here's the ground on the hinge pillar.

 

It's further up the hinge pillar than it might look.

 

I'm curious about "bouncing". Are the gauges working and just swaying with the car? Can you be a bit more specific and we'll see what I can do to help you. Are they more like working then off, working then off, or is it a swaying needle. By swaying I mean for instance, the fuel gauge is on 1/2 tank and when you turn it sway's up and down.

Fuel Gauge Help File 77-82 http://willcoxcorvette.com/repairand...lp.php?hID=277

If it was one gauge it would be easier to diagnosis. But I'll tell you that the oil pressure gauge and the fuel gauge are twins except for the fact that the oil pressure gauge is a bit more responsive than the fuel. They work on the exact same principle and they also use the same input value scale of 0 - 90 ohms.

Looking at the pinch connector from the center gauge cluster, the ground is the top left hand wire. You can verify this as a working ground by pulling the cluster out of the car.

Post again.

Willcox

 

Thank you Michael and Pete your post helped me find the ground. It looks good, no rust and bolted down tight.

 

So is the problem solved?

Jim

 

No I just got back from a test drive and shot some video of what is happining. I will try to post it today.

Thanks

 

Here is the video I shot today of my gauges after I replaced the printed circut and checked and cleaned all the grounds as mention above.

http://s1114.photobucket.com/albums/...arren_Collins/

 

Thanks for posting, the fuel gauge is more like swaying and it will do this even when the car is not moving. please see the video I posted .

 

The gauges are not moving in unison! I think you have two separate issues and I don't think the issue is in the dash. I'll watch the whole video and look close, with some stops and starts later today. But here is why I say this. The fuel gauge and the oil pressure are darn near twins with the only difference being the dampening fluid.

If this were a ground issue both gauges would be acting the exact same way and your fuel gauge is flickering toward the empty, while your oil pressure is trying to peg.

So.. maybe inspect the oil pressure wire at the sending unit.. see if it's shorting out on something. A shorted input wire will cause the gauge to peg.

I'll check back later tonight.

Willcox

 

Thanks for responding but I will not have the time to work on the car today, we have a birthday party for our oldest boy this afternoon and there is a good chance I will not be able to get to it till next weekend.

 

Couple of things. When you turn the ignition on before starting the car. Are the guages solid or do they bounce? At idle do the bounce?

Did you put the insulators back on the back of the the guage cluster panel? Or were they there to begin with? In my opinion you have a short or a bad connection.

example of insulators.


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Your problem is the top left gauge and bottom center in the pic. See how the plug feeds these two gauges on the bottom left....is the plug in right? How did the wires look on the plug?

Has anyone spliced into those wires for any reason. Both gauges only share things in common at the plug, alone some of the wires and circuit board. Something is touch somehwere and causing your problem...I think anyway. Your oil pressure gauge comunicates with the ECM but your gas gauge does not. But the harness that contains the the wire from the oil pressure sensor to the ECM is also shared by the wire that runs to your fuel relay in the comparment behind your seat. See if your relay is lying on the ground or touching the metal framing of the car. You could have pinched a wire too somewhere. You may need to remove the cluster again to figure it out. With a meter you need to isolate which of the wires feeding both those gauges is fluxuating is either. its a process of elimination. Then again if you did install the insulators on the board you may not have a short anywhere...just a cross feed of current....see it gets complicated...you may have other symtoms....radio noise?....lights flickering maybe....anything?

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Only the oil pressure bounces/flickers when ignition is on before starting. Both move when at idle.
I did not remove the insulators and I think I see them in the pic I took before replacing the printed circuit.

 

I do not remember seeing any splicing of the wires.
No lights flickering but I do have radio noise from time to time a sort of poping noise. I checked the radio with the ignition on and car not runing tonight for about 20 min and no noise and the oil pressure was flickering. When I pluged the harness back into the cluster I did make sure it was in good and I did not see anything wrong with the plug or the wires in it. I will pull the cluster this weekend to see if it came loose while puting it back in.

 

Something is a muck for sure. But while both gauges do share a common ground, they are for the most part the same gauge. You could if you wanted, remove the face from one and swap it. The oil pressure would be more responsive to change but it would give you an accurate reading as a fuel gauge.

So my thinking on this is that there are two different problems and based only on the fact that the two gauges are not doing the same thing. If it were a grounding issue I would think both gauges would do the same thing.

If a fuel or oil pressure gauge has a burned resistor or is without one, it will read a steady 1/4 value and it would be steady. It would not fluctuate as illustrated in the video. So we can eliminate that as the problem.

I really think the input ohms wires need to be checked on both gauges as a starting point. IMHO

 

Thanks, I will see if I can find a tester and what the ohams should be or I just might have to break down and take it to the shop.

 

Thats the back of yours right? The missing nuts? You took the pic after you took the nuts off right?

Willcox will probably know the answer to this. The yellow insulator I see on the oil gauge....should that be there? Did you get this flicker before you changed the board? Did the flicker start after something you did or did you get the car that way?

Interesting you get a flicker in the on position. Try this turn the ignition on. Sit in the car and get someone to bounce the rear up and down so the gas in the tank moves around excessively. Does the flicker get worse on the oil gauge? Its tough trying to figure this out via internet. I am only asking you to do the things i would do if i was there.

Jim