Hello everyone

I have an 85 with the digi dash. I have some flickering and inaccurate gauged issues I am trying to figure out.

When I am at a hot idle, my oil pressure reads in the high 20s. The second I turn my AC on, my oil pressure goes down to 5-10ish. I can turn it to "vent" mode with no cool air and same issue. I can even turn the fan speed down a bit and my oil pressure goes up a bit accordingly. It isn't just AC. If I turn on my headlights, I drop down about 2 PSI in oil pressure. I have also noticed my coolant temp is off too. My coolant temp will read 220, and I turn on my AC and it is instantly at 250. Turn the AC off and a literal second later it is at 220 again.

My dash also likes to flicker. It also dims when I use my turn signal, in rhythm with the turn signal.

My speedometer and tachometer always work correctly and with the AC off the dash usually works perfectly with no flickering. It is also very bright, not faded or anything like that. It doesn't seem to do this nearly as much when the engine is cold after it first starts, it is only after it is warmed up that the gremlins start popping out their heads. The system reads normal voltage on a multi-meter and there are no check engine lights. Overall the car runs great aside from this issue. The dash visually looks great

I have a brand new battery and a brand new alternator. The battery I had to buy anyway and the alternator I had suspected was the cause of the issue but it wasn't. I cleaned the battery terminals, replaced the terminal bolts, and I have cleaned the G201 ground that goes to the dash and all that didn't help.

Anyone got any advice?

 

Go to batee,com and check out the videos on there. You can buy parts to rebuild it yourself or sent it to them to do it for you.

 

Read the batee info in reference to ground problems on C4 corvettes. I experience the flickering also and need to clean / repair both the engine block and bell housing grounds. It is my next project. One is called G104 ground. I am not sure if there are 2 seperate grounds or just one, again, this is my next project and I am currently looking at how to reach them and if there are 2 or just the one. I can see the wires on the block so I know it is there. There are also ground straps that run toward the battery that are green and crusty looking so I knew this would be a number of repairs and not just one. Yours definetely sounds like it could be a ground problem. Also, there are connector issues (cracked solder joints) within the digital dash that the batee kits addresses.
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This is my list of grounds, I can not guarantee the accuracy of the year. So far it has been accurate on my 87 coupe.

G101-near RH side of battery, on frame.
G104-on block, above oil filter
G115-on frame, behind LH park/turn lamp
G116-on frame, behind RH park/turn lamp
G117-LH side of engine compartment, on front cross member
G125-behind RH kick panel
G201-behind I/P, near LH side of steering column
G320-LH B pillar
G400-on frame, above LH rear wheel
G401-base of RH B pillar
.
.

 

Thanks Vets-vet. I looked at my ground strap and I can see it is also green and crusty. I didn't think of cleaning the ground on the back of the block. I thought for some reason the G201 ground and ground to the frame were the only ones that would relate to the dash.

I might just end up replacing the whole negative cable. It is only 20$ on rockauto. With the battery cables I have found that half the time if the connection is corroded the inside of the cables are as well. I will also replace that ground strap with this one.

Hopefully it is just a ground issue and I don't have to take apart my cluster. Looking at the batee videos it looks like a PITA

 

Today when I started the car the temperature climbed normally to 225ish and then all of a sudden started climbing up very rapidly. It was 250 and I started getting worried. 10 seconds later it was 270. I shut the car off, turned the key into the accessories position, and all of a sudden the temp was 230 Looking back now I see it started climbing rapidly when the radiator fan kicked on.

Started the car again, yep, 230. Screw it, lets go for a drive and see what happens.

Drove down the road. Turned the AC on, all of a sudden I have zero oil pressure and then a few seconds later the voltage light pops on too


I personally find the zero oil pressure hilarious when the engine is idling smooth as butter. These old engines are so darn reliable they don't even need oil pressure...lol

My dash problem is definitely getting worse. The readings are completely unreliable now. I ordered a ground strap and new negative battery cable since both were cheap. I will replace those and clean whatever other grounds there are back there. After looking at the batee videos I have a feeling my issue is related to the cluster itself though. Probably a loose solder connection or something.

Anyone know if there is an easy way to get a secondary coolant temp gauge so I can see what my actual temp is? I don't really feel safe driving it around not knowing the coolant temps. Oil pressure I don't care about as much.

 

If you can solder well, the batee kit is just a matter of organization, but the ribbon and the connector (internal to the display) is kind of hard, again, if you can solder well you can do it. If not, send it in to them if this is within your proposed budget for the car. If I remember it is $250 ish full DIY kit and $560 or so sent in. Can you tell if your polarized film is aged ?

DIY full kit is replacement connectors, power supply, polarized film, soldering supplies (not the iron) and dimming components (maybe a couple more).

Batee also states the cars harness connectors to the display itself can be iffy.