I picked up a really rough set of clusters for a 1959 Chevy truck. I blasted and painted all the housings and faces. I have two electric temp gauges that start on "C" then after I rev the engine they peg out on "H" even on a cold engine (no over heating issues this is gauge related). I have read that the gauges need a good ground to work properly. However I have an electric fuel gauge and electric amp gauge and they work fine. Since I painted the back of the housing would this be a cause? Originally it was bare metal. If it is a grounding issues why would this only affect the temp gauge and not the fuel or volt gauge? Which settings should I use on a voltmeter to bench test these? Thanks in advance
Did it work before you did all your work on the clusters? Do you know what sending unit you have? The AMP gauge is not connected to ground in any way, so that is irrelevant. But the gas gauge does use ground for it's return circuit, just like the temp gauge does. I would start troubleshooting by measuring the resistance of the sending wire, relative to ground, when the wire is unplugged from the gauge.
Thanks Guys, I have no history on this cluster or the gauges. This is a secondary cluster I am learning on. I have the original cluster in my truck and everything on that cluster works fine. The problem exists only on the secondary cluster. The only thing I haven't tried yet is to put the unknown temp gauges in the good cluster. Sender is one screwed into the intake (283 engine). Jim sorry I am a bit illiterate when it comes to electric. How do I do that with a volt meter?
59Apachegail-while you addressed your question to Squirrel, he might be busy and I'm just sitting here having lunch, so - most of what we refer to as volt meters are more accurately described as VOM meters, they are capable of measuring volts (ac & dc), Ohms, and depending on their complexity, lots of other useful stuff on your car. It's not a volt meter like is on the car, but a separate and useful tool. They run from about $10 to over a hundred, but you only need a simple one for most automotive use. There are many good explanations online on how to measure resistance with these online. Just another thing to learn and add to your store of knowledge.
Thanks NM, I'm on my second VOM I burnt the first one because I didn't know how to use it. I dug through YouTube and google-d but haven't been able to hack it yet. I am afraid to damage another one. Electric is still very much a black art to me since I can't "see" it. I am a visual learner. What settings would one use to measure resistance? Thanks again
Here's two I have at the shop - the red one is a Craftsman, the black is Radio Shack. - on the red one the ohms scales are down there in the 6 to 8 oclock position, on the the black one, it's the K ohms setting (ohms is the little horseshoe shaped thing). Most of the VOMs come with a pretty basic instruction set. and don't try measuring resistance on "hot" circuits.
To answer the question about paint, and grounds...yes, the gauge needs to be grounded, and they didn't have paint on the mounting point for the gauges originally. Make sure there is bare metal to metal contact on the whole ground circuit, from the truck's dashboard, through the cluster housing, to the gauge itself. If you painted stuff that wasn't painted originally, then you need to scrape off some paint where the screws hold things together, so there is bare metal to bare metal contact. Learning about electricity is fun, I'm glad I got that basic part over with 40 or so years ago. It makes it more difficult to help you troubleshoot electrical problems, if you don't know the basics. Hopefully we can get you to understand. It's not magic, but it is a bit different working with stuff you can't "see" what's going on. The volt and ohm measurements will hopefully let you "see"...but you need to understand what they mean.
Here's a couple of tutorials on meters... One on the meter, and a link in it on actual use. A few things that bear repeating is make sure you select the right measurement/scale for whatever you're checking, and use ONLY the volts/amps positions when checking live circuits as well as making sure the 'scale' selected is at least as high the expected values you're measuring. http://www.xs11.com/forum/showthread.php?t=35338
Hi Apachegail.A little heads up here.If your sending unit is a one wire sender,it grounds through the sender body.So don`t use any thread sealer on the sender as that will insulate or partially insulate the body of the sender from where it is installed.Take it from me,you will get some strange readings from the gauge. Good luck.Have fun.Be safe. Leo
Thanks NM, My VOM looks like your red one Thanks Jim, Will scrape some paint off. I'm getting better at the electric. The will is there but I keep letting the smoke out of my wires... I'll get there! Thanks Steve, This will definitely come in handy, I already learned what happens when the settings are wrong. Thanks wood butcher and 325w! I will run at it again and report back soon.
if you contact the wicked witch of the north she has the ability to capture the smoke and reinstall.she has no internet or cell phone.in the mean while do as others have said and read on use.posting a no smoking sign in vicinity of work will not work either old wives tale
I had the same problem in one of my cars. Temp gauge would pin at H within 1 minute of a cold start. Simple fix. ..... wrong sending unit.
Thanks chopped, sender is working with the "working" gauge but not playing nice with this other one. Alligator clips are my helper hands. I get 0.2 @ 200K just after the coils On the back I get .05 @20K Same deal on my working one .05 @20K So maybe it IS the lack of ground?
Thanks Jim! On the questionable one: I get 85 @ 200on the coils I get 37 @ 200 on the leads On the good one: I get 52 @ 200 on the leads Does the difference in resistance mean either is better?
The gauge has a ground connection to the gauge mounting plate. The connections to test are: Ign post to ground, ign to sender post, sender post to ground. They should each have continuity. Let us know what you find.
Thanks Morrisgauge Nothing at 200 2k I get: .223 on sender to ground .224 on Ign to ground .037 Ign to sender
K means 1000. so if the meter works the way I think it might, when you have it on the 2k scale, and it reads .223, that means 223 ohms.
Per my poorly hand written notes: Ign to ground: ~150 ohm Ign to sender: ~40 ohm Sender to ground: ~190 ohm Allow some wiggle room for spec and your meter. To return to the issue you are having as stated in your original post: if your fuel gauge is working and you are having the same "spiking" temp issue on two different gauges, you should check the sending unit and wiring. Generally speaking, most temperature sending units start out cold with a very high resistance value to ground, then as the engine heats, the resistance value decreases. Years ago, we used to see a lot of aftermarket senders for the AC gauges that would start out normal, then just keep climbing. Currently, a sender made by Lectric Limited seems to be accurate and well made. Our customers have been using them for some time. They can be found here: http://www.lectriclimited.com/mainpage.htm I want to say that your sender should give about 80 ohms at 220 degrees and 120 ohms at 180 degrees, but don't quote me. P.S. Often with those gauges the frame rivet comes loose. Be mindful when handling any gauge, but aware that the rivet is usually work hardened brass and prone to breaking.
Thanks Jim, Morrisgauge, lots of great info here! When I swapped in this gauge cluster it blew the fuse on the back of the head lamp switch and sadly it also blew out one of my correct T3 headlights Could this be part of the issue since the inside lights circuit was down? Question about the rivet, can it be replaced if it does break? Would aluminum be ok or would it have to be a brass one?
It sounds like you have a few issues occurring simultaneously. I am not familiar with the head light switch circuit, thus will deffer to anyone that is. As per the rivet, either material would theoretically be fine. I believe the issue is that the original brass was forged 57 years ago and has been vibrating/expanding/contracting ever since. Unless it is broken or noticeably loose, I would leave that repair for another day. Not to plug our own services, but, you can get a lot of time into gauges with mixed results. Generally speaking, it would be my recommendation to have your gauges serviced by a professional shop. That way they're plug 'n' play with warranty.
Morrisgauge thanks a lot for all the info, much appreciated. I may send them out to you, for now it is learning. Thanks again all for taking the time to explain testing with the VOM that is something that will come in handy. I guess the mistake I made last time was testing under power. I am going to work on my grounding issues. I did lose a T3 but at least now I have a bulb to cut up for an eventual halogen or LED upgrade.
One last installment here, seems like one gauge is completely dead and another works. I took them as far down as I could and polished up all mating surfaces. I scraped the paint off the rear of the housing as well. Connected everything all up and bingo! Now I have a spare set just in case. Before startup After about 5 minutes running Thanks again all!
Congratulations! on both your interest in learning and your accomplishments to date. A few bits of info that may help you 'visualize' electricity..... For an electrical circuit to function, it has to indeed be a "circuit" meaning the flow of electrons has to get back to the source. The 'hot' or '+' is generally considered supply side. The 'ground' or '-' is the return path AFTER the appliance has been powered, whether that is a lamp, a starter motor or guage. Any failure in the path or connections in that circuit interrupts the flow of electrons by either reducing the flow below a useful level (aka excessive "resistance") or not providing any path at all ("open circuit"). As you have been learning above, the measure of Resistance is expressed in Ohms.' As for the terms, Volts (Voltage) and Amps (Ampheres)........think of them in terms of water flow. A garden hose for example. Voltage is the water pressure........Amps is the volume of water flowing. A change in either changes the other. Water hose, fully open nozzle........lower pressure but good volume flowing.......restrict the nozzle (Resistance) and the pressure exiting the nozzle rises and the volume decreases. If you took the connected Positive cable from the battery and touched it to the battery Negative post you would have the unrestricted "water flow" alluded to above. You would also have a lot of sparks and melting battery terminals and cable insulation!! But, when you put a starter motor in between the two posts, the internal windings of the starter motor put that current flow to work and the cables do not melt, but do conduct the flow of electrons back to the battery for a complete circuit. The same thing occurs with any other appliance in your vehicle, just at lower levels of current flow. Ray
Thanks Ray, The explanation makes a lot of sense. That battery example is how I blew up the first VOM. I had a flakey battery and my alt was charging it and zap. This is a fun journey, lots to learn!
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