Erratic gauge operation

[svalkid]

I know there are threads on these things, but I wanted to put all my problems in one.

Tach: Stock tach does not operate at all, never has. I bought a new engine compartment harness for it. Hooked it up to the neg. side on the coil, continuity all the way to the tach. (Tried the pos. side also). Have power to the other terminal with key on. There is not a ground wire, does there need to be? Wire diagram doesnt show one.

Fuel gauge: Didnt work then suddenly did work, now it doesnt work. What the HECK!

Oil pressure gauge: Always worked then didnt, now it does. What the HECK!

Engine temp gauge: Works good

Alt. gauge: works good

Thanks for some input. Paul

[b5blue]

Read this:  http://www.dodgecharger.com/forum/index.php/topic,37999.0.html

[Dino]

The tach does not need a ground wire.  It is grounded through the housing.  There could be several reasons why it does not work.  You could open it up and test the circuit board or simply replace it with a more modern circuit board from RTE.  Even if you don't get that one, do consider buying their solid state voltage limiter before the stock one dies.  When mine died it fried fuel, temp, and oil gauges in seconds.

Check the grey wire running from the bulkhead connector to the oil pressure unit.  If that checks out then skip a few steps and remove the circuit board from the cluster.  Measure continuity a few times.  Mine would have none 1 out of 3 tries on a few parts of the board.  Check if the pins are loose and while you're at it, clean the board and solder the pins to the board.  Check continuity again, it should be fine now.

If the oil gauge still does not work properly then check the gauge itself.  You can do this easily by putting the temperature in its place to test it.  The gauges are all the same, it's just the faces that are different.

Same with the fuel gauge but also check the wire and the ground strap at the sending unit.

[svalkid]

Looks like I will have to pull the cluster out. Never done that. Is it difficult?

[Dino]

Not terribly no.  I have a 69 so it may be slightly different.  If you have A/C it's a bit harder but still not bad.  My problem with doing this is the bezel.  My A/C center dash pad is a bit warped on the side and I caught the bezel o it once, breaking off a small corner.  I've re-glued it 4-5 times now.

Disconnect the battery.  Remove steering wheel and 6 steering column bolts: 2 that attach it to the dash and 4 to the firewall.  On the firewall plate is another attached with 2 bolts, you can leave those in place.  Removing these 6 bolts will lower the column out of the way.  Remove the radio bezel and the 5 black phillips screws that hold the cluster to the dash.  Gently pull the cluster toward you.  If it's like mine, it won't come out very far so what I do is start moving the left side out so I can stick my hand in there to disconnect a few things.  At least you don't have that fragile vacuum hose clip to worry about.  Headlight switch connector has a tab that needs to be lifted to remove.  The cluster will come out more and more until you can lay it face down on the column.  Use a towel to protect both.  Disconnect the ammeter wires and pull the whole thing out.

Once you have the cluster face down on your bench, remove the screws that hold the bezel.  Take a small screwdriver and stick it in the tach clock knob.  Pull the knob and unscrew it.  It's a very small cylinder in the knob so be careful not to lose it.  Grab some needle nose pliers to remove the small clips that hold the lens to the cluster.

You now have access to all the gauges.

When you are ready to put it back together there's only the lamp sockets that can be installed in the wrong spot so make sure the socket with red wire goes to the speedometer's high beam indicator, green goes to L turn signal indicator, brown to right.  Black goes to brake warning, 3 orange wires go to clock and speedo.

There's a small brown wire connecting washer button and wiper switch, you can leave that in place so not to lose it.

[svalkid]

Wow Dino, thanks for the quick info. Tried to pull it out once before but couldn't get it out but maybe a 1/2 inch. Didn't think about dropping the column down.

[Dino]

Wow Dino, thanks for the quick info. Tried to pull it out once before but couldn't get it out but maybe a 1/2 inch. Didn't think about dropping the column down.

You're welcome.

On a 68 you can remove it without dropping the column because of the different upper dash pad, 69 and 70 you have no choice.

Forgot to tell you.  The speedometer cable will likely disconnect when you pull the cluster.  When reinstalling you can attach the cable last from below if you don't have A/C.  If you do however then there's very little access.  Easiest way to do it is to find the speedometer cable retainer in the engine bay and simply unhook the cable.  Now you have several inches of slack which makes it a lot easier to do this.  When pushing the cluster back in place you may have to guide the cable back through the firewall until the cluster is in place, then hook it back into the retainer.

The metal cluster housing acts as ground when screwed into the dash so if you want to test the cluster just before you slide it in, simply attach the housing to the dash with a wire.

[svalkid]

Well I pulled the cluster out and found a big dead moth rolling around in the fuel/oil pressure gauge, probably causing the erratic op.
And found the tach PCB fried. No wonder it never worked. Sounds like a RTE board is in order? Also, the voltage limiter, is that the little box on the
backside of the cluster?

[b5blue]

Yea you want an RTE voltage limiter...much better than stock! 
http://www.dodgecharger.com/forum/index.php?topic=59757.0

[Ghoste]

I don't want to laugh, but a moth?  That's a new one. 
Seriously though, I am glad you found the little bastard and are getting things sorted out.

[Dino]

Well I pulled the cluster out and found a big dead moth rolling around in the fuel/oil pressure gauge, probably causing the erratic op.
And found the tach PCB fried. No wonder it never worked. Sounds like a RTE board is in order? Also, the voltage limiter, is that the little box on the
backside of the cluster?

Amazing what you can find back there huh?  

The rectangular box with the three prongs is the limiter, the cylinder is a capacitor.  When you get the solid state limiter you can do away with the capacitor.

I told you there were two bolts holding the steering wheel to the dash.  That was a mistake, there's a third closer to the firewall, sorry about that.

The RTE tach board is definitely an improvement although I have heard that it does not fix the bouncing needle some have nor does it make it more accurate but it's hearsay so hopefully someone else can chime in.

I'm waiting on parts so I can use the guts of a modern tach in the old tic toc tach housing so I  never have to worry about that thing anymore.  I recently upgraded the clock to quartz as well and it works great.  I did both a tach and standard clock at the same time and left them running for 24 hours.  Spot on to the second!

[svalkid]

Well, I have a 72. Sounds a little different than yours. No clock and I don't see a capacitor, just the rectangle box with the 3 terminals.

Trying to search RTE on the web. looks like its RT-engineering. Cant find a site yet. Do you know where I can get that solid state limiter?

It will be nice to have a tach, bouncy or not!

[Dino]

I thought you had a 70 but it's the same so no biggie.  Looks like the site is down though.  Try later, just google rte limiter and it'll come right up.   

[b5blue]

Check here the web sight for "Real Time Engineering" is not responding right now.
http://www.chargerspecialties.com/gauges.htm

[svalkid]

Sent out an email to 'tachman' and RTE. probably wont hear from them till Monday. Guess I'll take the rest of the weekend off.

[svalkid]

Got my tach back from Tachman today along with solid state limiter. Installed it tonite. Bitchin! It works great! Just reving it in the shop, no jumping around needle, works smooth. Cant wait to take her out tomorrow. Oil pressure gauge now works. Gotta figure out the fuel gauge now.

[b5blue]