Warm weather coming want to iron out some electrical issues

[meepbeep69]

We are coming out of hibernation but snow is forecasted for next week.

I cleaned up all of the electrical connections in the dash and steering column, put in the new thumbwheel dimmer switch and all lights are working as they should except the Temp and fuel gauge.

The brake light, oil light, bright light and blinkers in the instrument cluster, instrument cluster back lights, ights and brights dome light all work well.

How can I find out if the temperature guage itself and/or the fuel guage itself are working? Are these two and only these two controlled by the 5 volt voltage limiter? I have an extra one both pulse when twelve volts are put to them. One is much faster than the other. I am using the slower one now.

I'm in no way an electrical guy but have one coming over with his meters etc.

Can someone give me some written guidance so I can paint copy and paste a message over to him and we can hopefully get this going good by springtime? Thanks..... :drive:

 

[Jim S.]

Yes both the temp and fuel gauge use the limiter. It's hard to check those limiters with a multimeter because they put out a pulsed signal similar to a square wave. You really need a oscilloscope to check them or just trial and error but, be careful because sometimes they get stuck putting out 12 volts. Best option is to switch to a solid state regulator. Here is a link on how to do that. I did this on my car but I added a 2 amp inline fuse between to regulator output and the dash hookup. You can get a 7805 and capacitor at Radio Shack. If you need a regulator and cap I could mail you them, I have lots of that kind of stuff. (Ham radio operator)

http://www.allpar.com/history/mopar/electrical2.html

There is also a commercial unit that just plugs in for about $50 that has a lot of current and over voltage protection incorporated into it.

http://rt-eng.com/mediawiki/index.php/RTE_ABlimiter

 

[meepbeep69]

Given everything else is working then it would be the limiter?

I can pop it out and put the other one in. But nothing has been that easy with this rig.

I still have to adjust the shifter. It is very very close up against the dash pad in R, 1 and 3.

Anybody have any pictures (Bob) of which linkage to play with? It was centered with the pin.

Happy Saint Patrick's Day to you guys.

Beautiful day in Chicagoland today with temps in the mid 60's.

 

[Jim S.]

You can ground the fuel sender lead and the temp lead and both should read max. If that works or just one works, that will tell you that the voltage limiter is not the problem. If neither go to full scale then, the limiter is probably bad. I found the article of a guy that put one of those 7805s into the old can of the limiter and then it just plugs in. Pretty slick.

http://www.moparts.org/Tech/Archive/elec/11.html

 

[A31PKG]

Yes, with the key on, grounding the wires at their respective sending units is the quickest way to determine gauge function. Don't leave them grounded too long, just long enough to observe needle movement. By doing this you are testing the entire circuit - less the sending unit. If neither of the gauges work by grounding the sending unit wires, then you will need to crawl under the dash and ground the sending unit gauge lugs individually. I have attached a pic for reference. If they still dont work, then using a DVOM, check for a 5 volt reference voltage at the appropriate terminal of the limiter. You should also measure 5 volts at the input lug of both gauges. If you don't then move the tester lead from the lug to the copper of the circuit board - there should be a little ring of copper exposed to do this...if you measure 5 volts there, then it's likely that the connection is poor (corroded/oxidized) between the gauge lugs, the pal nuts, the copper circuit board, or a combination of the three. I've seen this time and time again over the years. Simply loosening the nuts and re-tightening (not too tight) will probably fix the problem. A better fix would be to remove the nuts and gently polish the exposed copper - a pencil eraser works well - then apply a dab of dielectric grease and re-install. Hope this helps!

Edit: If you want to view a full needle sweep, that's fine, just remove the ground when the needle reaches the end of its travel.

 

[meepbeep69]

I grounded the wire for the temp sending unit on the core support/radiator support. Got in the car hit the key and it pegged it.

Fair to assume I need a new sending unit? I don't have the rallye guage and don't have an idiot light so which one do I get? After looking on line.------where can I get one?

Where is the line for the gas tank that I would check? Concrete in the garage is still really cool!!

 

[mac]

napa ts6178

http://www.napaprolink.com/Detail.aspx? ... 0215167232

 

[meepbeep69]

Got a look at the electrical line running to the gas tank. I pulled it from the tank connection and grounded it. The needle went to full.

I cleaned up the connection as best I can laying on my back. I jiggled the ground strap. It seemed to be clean but I really can not get a good eye on it.

Now at least I know I can button up the dash and concentrate on the back end for gas gauge and front for the temp sending unit.

What are the procedures on the gas sending unit?

Thanks for the NAPA lead.

 

[A31PKG]

The fuel sending unit is held in place by an interference-fit ring that wedges itself under 3 (if memory serves) tabs built into the tank. Remove this ring by turning it counter-clockwise. You'll need a brass drift and a mallet to coax it around. Once the cutouts of the ring match up with the tabs, the ring comes out, and the sender can be removed. There is a rubber gasket between the sender and the tank. Also be aware of a grounding strap that connects the outlet pipe of the sender to the fuel line that runs along the frame. Often times these go missing over the years and can cause fuel gauge issues. Most MOPAR vendors sell them.

 

[meepbeep69]

I was able to check continuity from the tank to the upper fuel line and the strap itself is ok.

The tank is new...er...sat for about six years before it got filled.

I will order in a sending unit, RR horn emblem ( I wasn't gentle enough).

Thanks.