TIE_Pilot

I've asked for help here a few times putting the dash/interior of my '73 back together... so thanks to those who have offered help...

My question is this... my speedometer and tachometer are driven from mechanical cables, and I know that they work. All of the gauages in the center console seem to be driven electrically, and I don't know if they work. (Well, actually I'm pretty sure the clock is broken...)

Is there any way to just test the gauages by putting a voltage across their terminals on the bench? I have no idea if the problems I am seeing are the gauges, the sending units, the wiring, or rusty contacts on the back of the gauges. I need to narrow it down to figure out what I have to work with here.

Is there any way to clean up/restore the contacts when they have a layer of rust on them?

Thanks again...

Peterbuilt

If the gauges are in the console you can test as follows:
Temp Gauge-with key on remove the wire from the sender ( between plugs 1 & 3 ) temp guage should now go to cold.
Ground the wire- gauge should now go to hot.
Oil gauge-with key on remove the wire from the sender and oil gauge should go to high.
Ground wire and gauge should go to low.
Fuel gauge- with key on unplug the wire on sender at tank- gauge should now read full.
Ground sender wire and gauge should now read empty. PG.

gldnkngt

The oil gauge should be mechanical not electrical so I'll by-pass that one. As for the temp gauge, If you put 12 volts to the bottom quick connect and ground to the middle one it should go to just below 100. If you put the ground to the top quick connect it should peg past high.
As for the Batt gauge, if you connect ground to the top post and just touch 12 Volts to the bottom, the needle should deflect downward. if you connect ground to the bottom, and touch 12 volts to the top, it should deflect the needle upward.
The gas gauge, if you hook 12 volts to the bottom terminal and ground to the top the needle should go to empty. Connect the ground to the center stud and it should peak past full.
I hope that helps a bit.
www.harrisonspeedometer.com

TIE_Pilot

That is all helpful information, so thanks. Is the oil mechanical? I haven't actually tried to connect them all yet, so I must have just not been paying enough attention.

Peterbuilt

Gldnkngt, I never knew how to bench test before, thanks for the information.
Tie_Pilot, my 74 has an electric oil gauge, not sure if that was the first year of the change over. PG.

gldnkngt

I may be off on the year they went to electronic oil gauges. But give me a shout if you have any questions. I'll try to be of help if I'm able.

DC3

73's have the mechanical oil gauge.

DC

TIE_Pilot

Yeah, now I'm remembering an "extra" mechanical cable in the bundle, and wondering what it was. So, the car is at my brother-in-law's house right now, and I won't be able to check, but... where is the other end of the oil pressure cable supposed to go? What's the sensor like? This is a new engine (put in before I bought the car) and I'm doubting that the other end of that mechanical cable is actually connected to anything...

TIE_Pilot

I got the gauges back this weekend, and the oil gauge that I have appears to be electrical and not mechanical. So, presumably, at least the oil gauage was replaced at some point. It's also possible that the entire center console that I have isn't original, I guess. Since there was a mechanical cable in the center console bundle, it seems likely that th wiring harness doesn't have the connection for the oil gauge. I guess I'll be running something myself if I want to get the gauge working.

Any ideas?

TIE_Pilot

Well, the clock is broken, and that's no surprise. It seemed to me like the second hand moved a tiny bit when I powered it up, but then nothing.

The battery gauge also appears non-functional. I'll have to look around and figure out what I want to do there.

The wiper switch is completely corroded and will need replacement. On the subject of corosions, most of the metal contacts are rusted. Would some sandpaper/steel wool be enough to make the surface conductive again?

Peterbuilt

Here's a link about a clock repair. http://www.pcfred.com/Vettetip/FixC3Clock.htm PG.

TIE_Pilot

Thanks for the link. WOW that looks complicated! I don't know if I"m enough of a perfectionist to go that far... Seriously though, I've got to prioritize first things first since my time is so limited... I'm pretty sure I can drive with just the speedometer, tachometer, and gas gauge. The temperature will be next after that, then oil pressure. I think it will be battery last and then the clock...

Young69Owner

The clock on my '69 comes out with two screws, so you may just want to replace it while it's out. Mine looked good, so it gets to stay. Low grit sandpaper is what i've used on rust in the past. It'll do, just be careful and take your time. If your oil gauge was mechanical, you would have a fitting in the center of the block near the firewall and it just pumps up oil into the gauge. There's no sensor at all. A spring probably measures the pressure. When I disconnect my top fuel gauge contact, it goes WAY past full, all the way to horizontal (I don't think you have to ground the wires, just disconnect one). It's a nice thought, but I know I can't hold that much fuel...

martinsw

Suggestion - You should try to remove terminals and clean them off before giving up and getting new gauges/senders - a pencil eraser works well, if worse corrosion, sand lightly with fine sandpaper). When testing make sure you have good +12 volt and ground connections - you can also use the pencil eraser on the flexible printed circuit connections, if you are carefull it won't damage anything and clean up the contacts....

If you want to semi calibrate your temp sensor - remove from head, ensure a ground lead between sensor and gauge/power setup, put sensor in a pot of boiling water ..gauge should read 212 deg F at sea level.

I have hooked up speedo cable to hand drill to test for liveness and no cable binding....

I also ditched my inop clock and put a vac gauge in its place....have clock on cell phone and replacement stereo....but seem to often have vacumn leaks from loose hoses, etc.

Good luck