Testing gauges out of the car....

[Kern Dog]

I'm trying to get all the gauges working in my "Jigsaw" '70 Charger.
Currently, everything works except for the oil pressure and temperature gauges. I want to replace just the bad gauges with used ones for now. Eventually, I'll have the cluster restored.
I have 2 other gauge clusters to pick from. I thought that I read in Mopar Action about how to test the gauges but I don't recall which issue it was. I do understand that there is a voltage limiter that reduces the 12 volt input to something like 9 volts? The magazine had a pair of AA 9 volt batteries with jumper wires to each other, if I recall.

I'd appreciate any tips on how to test the gauges, Thank you.

 

[Nacho-RT74]

Any DC voltage source up to 5 volts ( which is their voltage rate ) will work.

USB charger
Old cell phone chargers
Couple of 1.5 volts batteries in series ( 3 vilts are also enough )
Any generic DC transformator selecting 3 or 4.5 volts rate.

Even one 1.5 volts battery will be able to move the needle, just slower and getting a low reading

Etc...


9 volts batt works ( just one ), but just feeding gauges for a couple of seconds. Needle will climb up really fast and can get burnt the coil, but with care can be made.

 

[moparedtn]

The voltage regulator knocks things down to 5VDC actually. There is an aftermarket digital one
out there for sale if you like; I used one when going through Fred's gauges some years ago and
doing so eliminates the need for that noise reducing capacitor thingy back there, too.
I'd get the VR sorted before doing anything else; you might find the gauges return to life after
that.

When testing lights and gauges and such, just use common sense when approaching each, keeping
in mind what input they'd be seeing in the car - but half the battle will be continuity issues, found
with the usual voltmeter.
On the workbench, I have a 12VDC power supply I used some - but in other, more rudimentary things
like getting all the lights working, I just ran jumper cables from a battery and clamped the other end
of both positive and negative to my wood framed work bench (separated, of course).
No, it didn't catch fire or short out (wood being a lousy conductor) and gave me a handy power source
for using the probes from the voltmeter to rummage around on the cluster with.
Redneck? Sure. Did it work? Yep.

 

[Nacho-RT74]

Read continuity with a multitester works too, but nothing like confirm the needle moving up with a power source

 

[Kern Dog]

I wish that I knew someone locally that could walk me through all of the functions of this tool:

 

[Islandkent]

YouTube could be your friend.

 

[Kern Dog]

I didn't see anything Mopar specific.
Also, this computer of mine is on it's way out. Videos take a LONG time to load and then the resolution is not good.

 

[Nacho-RT74]

For continuity just set it on the beeper sign ( below the 1.5 volts For the batt testing )

 

[kiwigtx]

I wish that I knew someone locally that could walk me through all of the functions of this tool:

View attachment 1091375

• Start with the AC Volts - used for testing your house mains, factory - supply from your Network Provider. To perform a Voltage test - touch the two leads between any two points on the potentially live circuit ...if you strike two Grounds, a Zero reading will result. Between a Live and Ground...full voltage .... Take care, this testing is really not an amateur trial area...experience highly recommended.
• Next is your DC volts - same as above, except if you are testing as an example your car battery - set the dial to a higher rating than the 'known' source...in this case, 20 Volt scale. Touching the leads across any two points will give a reading. If the readout says a positive number - the RED lead is indicating the Positive terminal or point of test, and the BLACK will be Ground. If the readout is a Negative number, the BLACK lead is the Positive end, and the RED lead is Negative. Not too much harm can come from touching the leads on any two different points (just stay out of Mains AC supply boards etc)
• Ohms - Resistance measuring - touching the two leads across a DEAD or Isolated part of a circuit will show the actual resistance of that part of the circuit. A zero reading (or below 0.03 ohms) traditionally suggests a dead short - like a short length of plain wire. Be very careful not to measure live circuits with the setting on Ohms scale - you will at a minimum blow the meter internal fuse, or at worst, melt the meter, melt your hands and face, and potentially start a fire. Normally start working on the 2K setting, and move to the 200 Ohm setting if the number is too small (less than 0.5 Ohms)....trial and error will teach you.
• Continuity Test - this is a resistance test also, but will indicate anything that is a circuit normally (depending on meter). A reading doesn't show a true resistance normally....move back to the Ohms scale for a true reading. Think of this setting as a Voltage testing screwdriver...BTW...those things are lethal on Mains supplies.
• DC Amps - Current measure - the way to test this is using the two leads to 'replace' part of a circuit. That means, if you were to cut a wire on a good circuit, you join each of the leads to one end each of the cut. Handy for testing small loads, as most meters only handle up to 10 Amps. A fuse inside the meter protects from higher currents, and these fuses can be very expensive. If testing Amps (current) start on the highest scale - 10 Amps, and work down if the circuit permits. A smaller fuse protects the lower end of the scale. WARNING - Never test the resistance of a battery...you will destroy the meter and create a lot of temporary excitement.

Start with that Greg, and come back to me for the next lesson.

 

[moparedtn]

I wish that I knew someone locally that could walk me through all of the functions of this tool:

View attachment 1091375

Seconded. One of those deals where I know just enough about electricity to be dangerous.
(I have that brand also, BTW. I saw electricians using them on job sites and took the clue).

 

[kiwigtx]

That's a good starting meter @Kern Dog ... I use a lot of Klein tools myself.

 

[moparedtn]

View attachment 1091376

• Start with the AC Volts - used for testing your house mains, factory - supply from your Network Provider. To perform a Voltage test - touch the two leads between any two points on the potentially live circuit ...if you strike two Grounds, a Zero reading will result. Between a Live and Ground...full voltage .... Take care, this testing is really not an amateur trial area...experience highly recommended.
• Next is your DC volts - same as above, except if you are testing as an example your car battery - set the dial to a higher rating than the 'known' source...in this case, 20 Volt scale. Touching the leads across any two points will give a reading. If the readout says a positive number - the RED lead is indicating the Positive terminal or point of test, and the BLACK will be Ground. If the readout is a Negative number, the BLACK lead is the Positive end, and the RED lead is Negative. Not too much harm can come from touching the leads on any two different points (just stay out of Mains AC supply boards etc)
• Ohms - Resistance measuring - touching the two leads across a DEAD or Isolated part of a circuit will show the actual resistance of that part of the circuit. A zero reading (or below 0.03 ohms) traditionally suggests a dead short - like a short length of plain wire. Be very careful not to measure live circuits with the setting on Ohms scale - you will at a minimum blow the meter internal fuse, or at worst, melt the meter, melt your hands and face, and potentially start a fire. Normally start working on the 2K setting, and move to the 200 Ohm setting if the number is too small (less than 0.5 Ohms)....trial and error will teach you.
• Continuity Test - this is a resistance test also, but will indicate anything that is a circuit normally (depending on meter). A reading doesn't show a true resistance normally....move back to the Ohms scale for a true reading. Think of this setting as a Voltage testing screwdriver...BTW...those things are lethal on Mains supplies.
• DC Amps - Current measure - the way to test this is using the two leads to 'replace' part of a circuit. That means, if you were to cut a wire on a good circuit, you join each of the leads to one end each of the cut. Handy for testing small loads, as most meters only handle up to 10 Amps. A fuse inside the meter protects from higher currents, and these fuses can be very expensive. If testing Amps (current) start on the highest scale - 10 Amps, and work down if the circuit permits. A smaller fuse protects the lower end of the scale. WARNING - Never test the resistance of a battery...you will destroy the meter and create a lot of temporary excitement.

Start with that Greg, and come back to me for the next lesson.

 

[kiwigtx]

View attachment 1091382

Greg once said to me that I seldom contribute in the technical forums (untrue of course) ..... I am just doing my bit for humanity

 

[PP1383]

Hey Kern Dog,
This should help...

Sorry, I should have done an introduction post first, but thought I could help...
Will make that post number 2!!

P.S. The B body procedure for testing purposes is the same...

 

[moparedtn]

Greg once said to me that I seldom contribute in the technical forums (untrue of course) ..... I am just doing my bit for humanity

Scary part is, I understood most all of that (Pop gave me a redneck electrical edumacation when young), but
you get much beyond the basics and I get exponentially scarier.

 

[Nacho-RT74]

Hey Kern Dog,
This should help...

Sorry, I should have done an introduction post first, but thought I could help...
Will make that post number 2!!

P.S. The B body procedure for testing purposes is the same...

I must say any MINIMAL voltage variation will make a total different reading if this test is intended for gauges calibration, so a 3 1.5 volts batts in series which makes 4.5 volts IS NOT the correct procedure for calibration. However works for aprox readings checking.

Aside that, once load is applied, if the source doesn't have enough current to feed, voltage can get a decay. 3 AA batts are not intended for big loads, so mostly sure the voltage will drop a bit while checking. Gauges are a coil made with a reistor wire who gets heat and any heating device sucks some of load. This will change the reading if calibration is the goal. MAYBE 3 D batteries will keep the voltage better, but still won't be the correct voltage rate.

If just a working conditions checking is required, couple of 1.5 batts in series feeding straight the gauges ( no need for sender ) is quite enough.

A testing box For calibration can be home made. Is posted at dodgecharger.com electrical section, a fixed thread there.

 

[Ron_M]

Mopar Action's Ehrenberg had several articles over the years. Some of them are online and some in pdf form. Here's one (not a pdf):
https://www.allpar.com/threads/get-engauged-so-you-think-your-oil-pressure-doesnt-fluctuate.237019/
Apologies if a repost,

 

[Ron_M]

Firewall blocked on my end, here's another one:
http://www.moparmusclemagazine.com/techarticles/23241/
from:
http://www.moparchat.com/forums/vintage-mopar-chat/92990-gauge-testing.html

 

[Derwud]

I wish that I knew someone locally that could walk me through all of the functions of this tool:

View attachment 1091375

You don't know how to use your Tool, shame...

I grew up with Flukes... Fun stuff.

 

[Kern Dog]

I know the basic functions of it, I just have zero background in electrical systems.