73 Dodge Dart Sport Fuel Gauge Wiring

[wwwfora]

Hi,

I've read through all the posts about testing the gauge and sending unit, however, my gauge has no wires on it at all just the 2 terminals sticking out the back. Can somebody please tell me how it's suppose to look like. Is there a negative and positive coming from the sending unit? Or just one wire from the sending unit. I followed the blue wire from the sending unit to the underneath of the dash then lost the trail, because it's very difficult to look under there behind the fuse.

Also, my sending unit has only one wire going toward the gauge, is there suppose to be a ground?

Thank you

 

[wwwfora]

Bump,

Also, can I use a voltmeter to test the wire as I go along the wire? What setting and resistance should I see?

Thanks

 

[RedFish]

You should be able to find the single wire for signal sender in the trunk. It goes through a rubber grommet and down to the sender post. The ground is accomplished with a metal jumper over the rubber hose creating a continuous chassis ground path. If that ground jumper is missing you can create one with a small piece of wire held down with a small hose clamp on each end.
Easy testing, first , with the ignition switch on , pull the sender wire off the temp sender and check it with a volt meter. You should see flashing 2.+ to 3.+ pulses of current using a digital meter. Now put that back and look for the same current going on the fuel sender wire.

 

[wwwfora]

RedFish, you've been very helpful. Thank you. That's my issue, when I look up under the dash all I see is the screw studs sticking out of the back of the fuel gauge, and it looks like this also for the voltage meter and temperature guage, but they are working? I thought the wires were connected to the back on the studs? Is the wiring up inside somewhere. I don't know how they are working? These cars are suppose to be simple right? I have another quetsion about following the fuel gauge sending unit wire...

 

[RedFish]

those studs hold the gauges in and also connect them to the printed circuit board. The hard wires leave at the main panel connector.
I edited and added to the previous post, conserning test.

 

[wwwfora]

I'm starting to understand. So since all the wires connect up at the main panel wiring. I would like to test the wire from the sending unit all the way to the main panel connector for resistance. Which setting should be on the voltmeter? I can follow the wire to the 8 pin connector near the fuse box, then I lose it. My manual shows it as being Dark Blue all the way home. This would help me know if the gauge or the wiring is bad. Sending unit is new.
Thanks!

 

[RedFish]

The wirring harness to the rear of the car is difficult to access and or test. You need to check the simple sht and forget ohm testing that wire end to end. Find it in the trunk and connected to the sender. Check the sender for chassis ground. Finally pull the left front kick panel and check the wiring there.
The resistance in the gauge , isoluated on the workbench is 20 ohms but I dont have aclue what it might read installed . The other side of the gauge is connected to a voltage limiter with bouncing mechanical points inside.

 

[wwwfora]

lol straight to the point with that one. I'll do some simple testing and get back. Appreciate your time!

 

[wwwfora]

Red Fish can you give me 2 more answers, please?

1. Could it be possible that a bad voltage regulator can only effect the gas gauge and not the others?

2. I want to take my cluster apart, I've removed it from the dash, however I can't get the wind shield wipers knob off, looks squeezed on. i don't want to break it. The headlight knob just pulled right off?

Any suggestions. Thank you!

 

[RedFish]

Nope the voltage limiter supplys power to the gauges and either works or it dont.
The headlight switch knob wasn't supposed to pull right off the stem. There is a release button on that switch to remove the stem and knob as one.
The wiper switch knob should have a set screw in it. Some have a steel keeper that bites the stem. It is released with a 90 degree pick inserted from behind the knob , or is that a Ford thing ? Hope this helps

 

[wwwfora]

Yes, every bit of info helps. Yes I think the wiper knob must have a release on the rod somewhere behind the cluster.

So, can the gauge physically be damaged and are the repairable? Because all the other gauges work and there is resistance on the blue wire all the way up to the plug that goes into the printed circuit board.

Thanks

 

[RedFish]

he gauges are repairable but it aint cheap. Once you get the panel out you can check the gauge connections to the printed circuit board.
If there was a Ford type catch on the wiper knob it would be right behind the knob , not behind the panel. Look again for a small set screw in that knob.
The headlight knobs are made onto the stems because the get pulled. Its not supposed to pull off the stem. The wiper knob doesn't get pulled so the stem is built into the wiper switch.