Topic: Temp/Oil Gauge and Tach ?

[mikeb78ta]

Well I was really hopeful with that, however it didn't work.  I tried both Tachs also and the same as the past few days. My Tach does absolutely nothing, the spare just pegs out at 6000. 

[ta78w72]

I was hopeful too.  If that test light stays bright all the time, it means you're not alternating ground/ungrounded. 

At this point, since you measured voltage at the ground point of the tach you should wait until you get the new circuit in and then try.  If the car is running, your coil should be OK.

[mikeb78ta]

The new printed circuit will be here by Wednesday. Unfortunately I have to out of town for work tomorrow.  I am also dropping my car off at Trans Am Specialties of Florida tomorrow so they can re pin my door hinges and adjust my leaking drivers side door so I won't be able to do anything else after today until 10 days from now.  Oh well I wanted a project.  I sure got One...

[ta78w72]

You've been all over this board!  But that's how you learn.  Once you get to the bottom of the tach problem you'll never have another tach you can't diagnosis.

[mikeb78ta]

Thanks again for all of your insight.  I will post again when I get back from my trip and get that circuit installed...  Allit it is , is time and Money!!!

[mikeb78ta]

Hey Guys,
I just got back in town from a work trip.  I received my new printed circuit and I installed it.  I was glad to see that the oil pressure gauge and Temp gauge are now working.  I am not so happy that it still did not resolve my Tach Problem .  Any thoughts that the tach could be bad??

[ta78w72]

At this point you should replace the tach.  Buy a used cluster on ebay, or Classic sells new ones for gulp! $289.95.  I'd go for the used cluster myself.

[mikeb78ta]

I figured as much. there are a few I have looked at on e-bay.  I will get my hands on the non-quartz style and let you know how it goes.  Thanks.

[mikeb78ta]

Okay.  I am still really confused.  I recently bought a used Tach off ebay.  It is the same nono-quartz style as my original.  I changed it out withe the tach that was in the cluster.  the only difference is that is an 8k tach.  It doesn't work.  I changed out the printed circuit a few weeks ago as stated in previous posts everything else works.  Any new ideas? I tested the coil wire with a test light and there is signal coming from the distributor.  Thanks

[mikeb78ta]

My only other thought is changing out the distibutor, everything else is new? What do you think??

[ta78w72]

I wouldn't go into a parts changing mode.  Do you know any old timers that might have a hand held tach?  We used those to set the dwell in the old days.  Connect the hand held tach and see if it responds.  Also, that signal wire isn't simply a wire, it has a little part in it.  I'm not sure what that does but it may be a diode kind of thing.  Rick might know....he knows everything.

Basically all those tachs work off the same principle.  12 volts, ground and the signal from the distributor.  They're set for four cylinder, six cylinder, or eight cylinder.  As long as you have a tach from an eight cylinder, you should get the proper reading.  That 8K tach may not be working.  Or, if you have another car, you can connect the tach to that car if you know what you're doing.

Your printed circuit shouldn't affect the tach, unless there's a break in the circuit which leaks voltage to the cluster canister.

[mikeb78ta]

Good idea about the hand held tach.  Yeah I can get one from a guy I work with.  I'll try that first.  I am positive that i checked all the connections and that there is a solid ground at the new circuit and that all the steps you told me about before are connected properly,  It just seems weird that all 3 tachs I have are bad?  Im going out of town again tomorrow.  I'll keep you posted when I get back.  Thanks a lot for the ideas...

[Eagle 1]

I tried an 8000 rpm tach that I bought off ebay and it didnt work either.
The reason I bought the gage assembly was for the 160 mph speedometer.   I think you must have got another bad one from ebay.
Also make sure your panel assembly is grounded or the tach wont work at all.

[mikeb78ta]

I hear ya.  I've thought about just buying a brand new one.  I realize that it is nearly $300, but at least I can be sure of it working.  I now have 3 that aren't working for me.  Maybe they are good, but I know they aren't working for me.  I've checked the ground and my new circuit was put back together by me and I'm sure it isn't a ground on the circuit at least, but thanks for the info regarding the e-bay Tach.  Makes you wonder if someone is selling duds???

[ta78w72]

Connect the hand held tach at the tach connector first (the brown wire).  Unplug it from the rear of the tach.  You might have to run a jumper wire in order for the hand held tach connectors to reach the battery.  Don't let that wire ground or you'll ruin the module.  Check the rpm's at that place first.  If it works, you know you're getting a correct signal from the tach.  If it doesn't, connect the hand held tach to the tach terminal of the distributor to see if you get a signal.  If you do, you've got a bad signal wire.  If you don't, you've got a problem in the distributor.  You did change the module, didn't you?  I don't think the module's really involved but liked I said before, I've never seen a schematic of the module or a narrative of exactly how it works.