Hi all,

I'm having some gauge issues and I'm looking for some assistance!

1) Voltage gauge -- Never gets above the 13 mark on the gauge, even when the alternator is putting out over 13. Typically, the needle sits halfway between the 13 mark and the mark between the 13 and red zone. I'm getting 14.6v at the alternator with no load, 14.2 at the alternator with load (in Drive, A/C on, radio on, headlights and high beams on, rear defroster on, hazards on, engine revved to about 2000rpm.) At the battery, getting 14.5 at idle, 13.9 under the same load conditions as above. I even was able to watch the needle drop into the red zone while I was clearly getting the above measurements. I also checked the readings using both battery negative and negative ground (readings were within .1v) so I'm confident that I'm not actually having a charging issue.

2) Temp gauge -- RARELY gets past the first mark. Usually only moves a slight bit over the 100 mark.

3) Oil pressure -- frequently gives very erratic readings. Needle bounces a lot.

My first thought / question is, the combination of all 3 sounds more electrical (as opposed to mechanical, so is there a common ground for the gauges?

What I know about the cluster....The gauge cluster is not original, although I do have the original. The current cluster is from a V8 but the car is a V6. The cluster was changed out due to a "faulty" speedometer by the original owner (my father). I plan to get the old speedo checked by a speedo shop and my goal is to put that cluster back in. I think the issue with the speedo is at least in part due to a "bad" cable because while the "new" speedo is more accurate, it still has periodic "bounces".

I know that pulling the cluster is not one of the more "fun" jobs, so I want to get as much done/checked while I'm in there.

Anyone have any thoughts?

 

Well my voltage never goes above 13 either, even with a newish battery. For the temp gauge is your fan always running? Mine is and never goes above the first mark. Oil pressure probably isn't very accurate either. Mine was reading very low but would never go into the red, just stop right above it. A new mechanical gauge fixed that problem.

 

Thanks for the reply.

The fan runs when you would expect it to, meaning sitting at idle for a period of time or when the AC is on. But the needle only moves a little bit.

That's why I'm leaning toward an electrical solution rather than a mechanical one. The systems themselves (in as much as I can test them) appear to be in proper working order. It seems that just the gauges are wrong.

Case in point, I drove for 3 days straight with the volt needle hovering around the red. No starting issues, no power issues. If it had really been that low, I doubt that I could have used the car as a DD without seeing something.

 

The clusters use a thin film circuit board (copper circuits sandwiched between two layers of plastic film)that corrodes and splits, our cars are now between 20-30 years old. You need to pull the cluster and inspect this film for corrosion and breaks. A few months ago I rebuilt a friends cluster and he purchased a new circuit board online, but I don't know where. I'll ask him the next time I see him.

 

If you can afford it just throw the stock cluster in the garbage and grab an autometer cluster I got one last year and they are leaps and bounds better than the stock crap.

 

The cluster swap should be V8 to V8 or V6 to V6 (mechanical to mechanical or electric to electric).

Check the following link for mechanical speedo woes:

https://www.thirdgen.org/forums/inte...eedo-woes.html

JamesC

 

Would any Set of mechanical gauges work for 87 305 firebird?

 

Sounds like a ground problem. I had a similar problem with my iroc. Volt gauge reads low, and my temp read higher than it should instead of low. Make sure the ground wire (I think g200)to the left of the steering column under the dash is make good contact. If it is, make sure your connections are good behind the cluster. I took my cluster out and took it apart so I could clean all the connections on the circuit board and also cleaned the contacts on the connectors that plugs into the cluster. Did all that and everything works the way it should. But like JamesC said, make sure you install the right cluster for your car. Low temp reading could be correct though. Could have a stuck open thermostat or wrong one causing the low reading. Verify what your engine temp actually is.

 

Thank you. getting on top of it

 

Ummm Yes and No.. The Speedo will lose VSS (cruise) if you go strictly mechanical. Other than that, the rest should work ok.

 

Thanks for the heads up, i plan to use mechanical simply for water temp, oil pressure and battery voltage.

 

Classic Industries sells a flexible circuit board for our cars. A friend was having similar problems and this fixed it all.
http://www.classicindustries.com/cam.../25081605.html