another dash question

-
C

cnrtybyathrt

Active Member
Joined
Jan 11, 2010
Messages
34
Reaction score
0
ok temp and gas guage dont work did before i removed dash 2 years ago can short gauges over from a hot wire they move tried to run jumper wire from gas sending unit both hot and ground still doesnt move have ran new ground to dash
 
So what car are you working on? You need to be a bit more specific as to what you're doing and don't run all your sentences together. It sounds like you may need a new dash regulator however.
 
Both gages run on 5 volts from voltage limiter. 12 volts will cook them.
First you need to test the voltage limiter. Some of them are housed on the circuit board, and others are integral to gas gage depending on year and model A Body.

Second, fuel sending unit has to have a good ground. To test, pull wire off of sending unit ground it using a jumper wire. Gas gage, if in working order, will swing to full when the wire is grounded. This indicates a bad ground at the sending unit.
Factory used a metal strap with clips on each end. One end clips to sending unit, spans rubber coupling connecting fuel line to sending unit, and its other end clips to metal fuel line. These things become corroded and loose ability to conduct. Clean or use a jumper to establish a good ground.
Temperature sending unit is located near thermostat housing. Trace its wire back to gage making sure it is conducting. If the wire is good, the sending unit may be bad, or gage is bad. I don’t have my FSM nearby so I can’t advise on testing it from memory, but someone will chime in on a test method.
 
most likely i cook them, tested with 12 volts thank you i guess i'll look for new dash thank you
 
Kind of hard to understand what you have done since you use no periods to form sentences. It sounds like you applied +12 V directly to the fuel level sending unit wire. That might have fried your gas gage.

The original problem was probably the 5 V regulator, which for 1974 should be the metal box you see (not always if dash has a tachometer). You can still get originals, but better and cheaper to upgrade to an electronic one (ebay ~$20).

I think you can test the temp gage with no damage by grounding the wire. I recall that makes the gage go to the far right, but someone else will comment. The best way is to use substition resistors, and you can find the resistance vs temperature in some FABO posts, I recall.
 
BillGrissom said:
Kind of hard to understand what you have done since you use no periods to form sentences..
Click to expand...

YUP There are several trouble spots on Mopar dash clusters.

1 Is the cluster getting SOLID 12-14V from the ignition swtich on the power wire, traditionally dark blue

2 Is the socket arrangement for the voltage limiter making contact to the PC board?

3 Is the voltage limiter working?

4 Check or replace the nuts on the studs for the temp and fuel gauges, they get corroded and work loose.

5 Make sure the ground buss for the cluster is actually grounded. Usually, best way is attach an extra wire pigtail to the ground on the cluster, and bore a hole and bolt the other end to the column support

6 Make sure the pins of the PC board connector(s) are tight, repair, replace, resolder as necessary.

These gauges are a simple series circuit

The voltage limiter gets switched power on the "dark blue" IGN run line -- the limiter outputs about 5V to one side of BOTH gauges. The other terminal of the two gauges goes to each sender, one for temp, one for fuel.

DO YOU have a wiring diagram or shop manual?
 
ok what i did was jump(just touch) a wire from amp gage to the gas gage nut on pc board.the gage went to full. removed wire and noticed i lost oil light, was on with key on but not started.then i moved bulbs around it never came back on.then i jumped amp to temp gage same thing went to hot.then removed,then i ran wire from fuel sending unit to nut on pc board.didn't do anything.i still have dash lights and turn signal lights i hope this makes sense i do know now i screwed it up
 
You must log in or register to reply here.
-

Back
Top