Joseph Parsons

Hello all, I recently bought an 85 (early model) 23,349 in fact. 89k miles but needs ALOT of TLC.... I'm 42 and my wife finally let me get one as a project/ fun local driver.... Anywho I was so happy that the dash was ok I failed to notice a flux in the tach reading.... so today while making a little trip the tach was black for some of it and then, stated reading REALLY high...like 88 and stuff.... then low then off then , well just random stuff, plus my upshift indicator wasnt working either. The car was running ok, just wierd tach and no upshift... so any ideas fellow corvette lovers? made me freak out to glance and see it reading 88rpm while coasting at 27 mph :-)

1984Z51auto

If the tach is just acting "odd" while being driven, check the connections at the distributor "TACH" terminal and at the "TACH FILTER" (at the rear of the intake manifold). It gets hot and dirty back there and the terminals get ratty.

Joseph Parsons

Thanks I will do that...

I really appreciate all the input.... I had an 86 for 6 months as a kid... Didn't respect or treat it right, so this 85 is like a second chance... I'm older and ready now.... Kinda like Billy being ready for the Mogwai...
My 86 had the Upshift.... and Anti-lock, and climate control.... Amazing the differences in just one year... kinda wish I had the 86 , but hey I will make the best of it:-) Thanks again

PS I named her Onyx

gerardvg

The tach filter is a around 1.5 to 2 inches long and a bit over half inch diameter, it is bolted to the drivers side of one of the transmission to block bolts. (at 9 or 10pm position from under car looking to front)
Check the wiring to distributor and the bolt is tight, its not a high wear part.
My 85 has over 170,000 miles, original tach filter and original dash.

Cruisinfanatic

Probably the tach filter. You can see the wire from the distributor to it, but you can't see it until you remove the wiper motor

aklim

I think you can even bypass it.

Joseph Parsons

Thanks for the help... so here's the deal. I had planned to check the tach filter this weekend when got to the wiper motor to check the connections. ( My wipers only work on high, and i read it might be the connections, but that's another problem. Lets deal with the dash first) *takes breath* So yesterday before I was going to look at it, my son and I went to Auto zone to buy some new tools and low and behold during our trip the dash began to act stupid..... First time but hey I havent had her long... So it went completely out then after a bump or two it came back just fine for second. Then out again then on, but all jacked up looking... then out , then on, then real dim like was night...... *takes another breath*...... and now pretty much the same.... I am a fan of batee.com and his repair vids, so today i got the cluster out of the car, called his number*left message* and am going to mail him my cluster tomorrow to diagnose and probably re-solder the 12 pin connector. ( the symptoms point to that) .... So his prices are real nice, and seems real reputable....

So just a little update...my weekends are Monday and Tuesday so thats my Corvette days.... Goes to show, that on the way to fix one problem another one arrives.... Fun Fun Fun.... Still love my Onyx though... thanks again friends well get her right again.... Cheers

PS I think I found my horn problem too!!! The relay was missing... Gotta order a new one as well

gerardvg

Hi

the 12 pin connector and plug assembly is the part you need, tbere is a lot of load on those pins and they need to be replaced.
make sure you replace the backlights with the LED type to keep your dash cool and prevent the common overheating issues with the original backlight lamps.

i replaced the connector pin and recepticle plug was quite easy, also went to the LED backlights and replaced the light sensor at the same time.

my dash was playing up a few years ago after going off road the corrigations vibrated the dash and went blank ... first time in the 20 years of owning her. Has been great ever since.

Good luck

Cruisinfanatic

I'd be thinking switch to start, not the motor. Sometimes if you work the switch back and forth quickly several times, you can get the connections to work.

Joseph Parsons

Ya think Compressed air in the switch might help? Getting to that motors gonna be a bi%^$? I'll try air once I get my dash back... I try to focus on one repair at a time.... I did however order a new relay for the horn

PS with a huge nor'easter coming this week to Maine, not much else to do but wait for the dash from Crazyuncleburton anyhow...

aklim

I'd be very careful and not get carried away if I had to do that.