gauges not working

[Aussi440]

Mopar heads,

I've got a 68 charger, and my water, oil and gas gauges don't work right, it seems like it is a bad ground b/c sometimes the oil pressure will work and then go right back down, occasionally the water temp needle will move, and the gas gauge isnt very accurate.

I have a new Year One engine harness but the dash harness is original.

Do the oil pressure and temp sending units have to be a certain kind or calibrated a certain way to work?  Can I just use Napa Auto Parts sending units? Or do I need to use Year One Parts?

I bought the car about 10 years ago and they worked but not too accurate, they have been getting worse and worse ever since.

I was going to check the grounds today and make sure everything is getting power with my test light, but I wasn't sure if anyone had any ideas?  Is there a certain ground I need to check?  Let me know what you guys think.

[71_deputy]

I would check to make sure that the dash is grounded to the frame- better still is to make a ground wire between the dash and the frame.

next could be the voltage reg. for the guages- on the back of the dash.

[dkn1997]

I had a similar problem on my 68 before I refinished my cluster.  fuel gauge intermittent (even after new sender), other gauges a bit screwy.  Just the act of taking the cluster apart and putting it back together (necessary for a cosmetic freshening) fixed all of it.  I also calibrated them too with some resistors from radio shack. 

if you look at a cluster when it's out, each gauge has 2 studs that are part of the gauge.  one stud is for the sending unit input, the other gives the gauge 5v from the little regulator on the back of the cluster.  these two studs push through the cluster frame through a printed circuit board where they make contact via being tightened with nuts.  lots of potential for vibrations over the years to loosen them up or simple corrosion. 

remove and disassemble the cluster, clean the gauge contacts good, and re install.  not the easiest job, but I think it will fix your problems. while your at it, throw on a set of the gauge face decals and calibrate those babys and do a quartz clock conversion.  I did that and I get the biggest smile on my face driving down the road with my 40 year old clock keeping perfect time.

some helpful links:

http://1970chargerregistry.com/70messageboard/viewtopic.php?t=2018&highlight=calibration

http://1970chargerregistry.com/70messageboard/viewtopic.php?t=2055

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

[Aussi440]

Thanks alot, I was thinking of doing that.  Everything I try doesn't seem to work.  Have you heard anything about AutoInstruments.com and the type of work they do.  They are advertised in all the Mopar Muscles.  Ryan

[resq302]

Lots of people here have been having problems with Autoinstruments.com recently.  They did my gauges a few years ago and the coolant temp gauge is now reading 30 degrees higher than what the coolant temp actually is again.  I have heard good things about Redline who rebuilds and calibrates your gauges.

[poppa]

Try Mike. lilwendal1 . He's a member. Did mine,not hooked up yet but did a great job on the cosmetics.