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Yee ha! Well, I fired it up on it's own electrical system for the first time in what... more than 20 years?

"Almost" everything works. Oil pressure, tach - check.

Temperature guage? Not so much - also not sure eveything's 100% with the charging system.

Temperature gauge: Weird. Goes to below 100 degrees (limit of travel on the needle) and stays there -- until I let the motor idle down, then it creeps down towards the middle of the scale and bounces. It's acting like a tach, sort of - it moves "upward" (colder is "up" on the scale) as soon as I take it off idle and that's where it stays. I know the motor's warming up (duh) and it had to get close to 180 because the cooling fans cycled on and off (yay). I just tried completely disconnecting the lead from the sending unit, and it behaved exactly the same way. Weird.

Another weird thing. GENerator light glows faintly. When I first turn on the ignition, it's almost not on. Seems to gradually increase in intensity over the span of 20-30 seconds, engine on or off, whenever the ignition is on. Battery's new, and I keep it on a battery minder. Voltage is where it ought to be, 12.8 engine off - 14.3 to 14.8 engine running, and I see a dip when I turn on the heater blower on high, then it comes back. Voltage regulator (external) is brand new, got a good one (Echlin) from Napa. I did take the alternator in a few months back and had it tested. It showed to be good. Ground straps from block to body and from body to frame are in place and brand new.

BRAKE warning light comes on and stays on even if I press the pedal, but I'm mostly hoping that's just because I haven't finished bleeding the brake system yet so I'm not concerned - yet.

Headlight relay for ignition works great :) Thanks again Brian.

Does anyone have solutions to these mysteries?

Thanks,
Bear
 

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happy to pass it along Bear, i thought it was a pretty slick work around too, saved me the confusion of having to track everything back to the ignition and fuse block (like i am going through now with my brake/turn signals). my brake light stays on too and i am fully bled (just another electrical mystery to track down in time. I too was amazed when i put power to mine that everything lit right up and worked i have found a few splices in the trunk so i think the brake light turn signal thing is not new, next step fuse block, then i may just run new wires rather than tear my interior apart to check the ribbon. Can't wait to see that interior in your car so you can take her for a little spin....you must be getting antsy...i know i was did the whole interior in a 3 day weekend.....:cheers
 

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# 1000

Well how about 'dat? I think this here right here is my 1000th post on the forum. :party:

I guess it's appropriate for it to be associated with another milestone on my car, even if everything isn't exactly perfect yet.

I went out and shot a video of how things are looking, hopefully someone will be able to recognize the symptoms and point me towards some solutions.

Here's the link to the video:



Thanks guys,

Bear
 

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Bear, glad you're making progress. The dim light with okay charging could be a bad diode in the alternator. I've had it happen. The brake light on all the time could also be caused by this as well. It could also be that your proportioning valve (metering valve) needs to be centered. I think you have a custom system, so I'm not sure if your valve has a button on it or you need to jump thru some hoops in a certain order (bleeding the valve/system) to get the valve to re-center and turn off the light. I'd swap in a different alternator first....or, knowing you, take the old one apart and inspect it really close. Gauges: factory gauges not in use for decades can do strang things when put back into service. I'd personally drive the car a while and see if it settles down. If you don't want to pull the dash or pod later (and want to do it now),Pete Serio is 'the man" when it comes to this stuff. He helped me a lot getting my '65 rally gauges back into shape. As you know, he's on the "other" forum. You're getting close...can't wait to see video of it on the road!!!
 

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:agree:agree just one thing to add don't put teflon tape on the water sender. It can cause a bad ground and make the gauge act funny. The engine sounds sweet....Eric
 

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:agree:agree just one thing to add don't put teflon tape on the water sender. It can cause a bad ground and make the gauge act funny. The engine sounds sweet....Eric
Oh man! I thought sure that was it because I did indeed use teflon tape. I just checked the housing with my meter though, and it shows zero ohms resistance from the sender housing to ground. If that was it that'd explain why it acts the same wether or not it's connected tho. That part, and also the fact that the reading fluctuates with RPM, is bothering me because I can't quite reason out what woiuld make it do that.

If I understand right, these gauges are basically ammeters, and they work by measuring current flow. The magic is in the sending unit in that it provides a resistance path to ground that varies with either temperature or pressure. Do I have that right? (In that case I guess itd' actually more accurate to call them "receiving" units.. except in physics I learned that dc current actually flows from negative to positive so "sending" would be correct - making my head hurt here :willy:)

Bear
 

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If you don't want to pull the dash or pod later (and want to do it now),Pete Serio is 'the man" when it comes to this stuff. He helped me a lot getting my '65 rally gauges back into shape. As you know, he's on the "other" forum.
I just got it in so I'm not excited about pulling it, but if it has to come back out this would be the time to do it. :agree

I don't know Pete, but it sure sounds like I need to! I assume you're talking about PY? Does he go by Pete over there?

Thanks bro... :cheers

Bear
 

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is the cluster grounded good to the body? if the guage acts funny when its not connected then its feeding back from something else. could be causing some of the other problems too.
 

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Good point on the cluster ground, 66. Real good point. Bear, yes, you know how the gauges work--actually, as usual,you explained it really well! Just recieving units working on resistors or sometimes thermistors. For a gauge to fluctuate with rpm, that means the resistance or voltage is changing in the circuit as the rpm changes, and doing it rapidly. Shouldn't be. The spring in the gauge could be bad, or it could be a ground or a charging system issue(voltage spiking),or a resistance issue/short in a circuit of sender. Talk to Pete. He may know of a'pattern failure with these gauges and point you right to it!
 

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is the cluster grounded good to the body? if the guage acts funny when its not connected then its feeding back from something else. could be causing some of the other problems too.
Well, that's a good thought - I'm assuming the ground is ok because the oil pressure gauge is working fine, and it's in the same housing and uses the same ground as the temp gauge.

@Eric - Pete responded to my query and I think I may be on to something - at least it's logical. I think I may have a temp "switch" and not a temp "sending unit". I'd noticed that the engine harness had a connector that was different from what the connection on the "sending unit" was, but I made it work and moved on. Got to reading and thinking last night about how a gauge works - all the magic is in the sending unit which is really nothing more than a resistor that changes values with temperature. It provides a path to ground of varying resistance, and that variance is what the gauge reads and displays as temp. One of the keys to my half-baked logic is the fact that my temp gauge behaves exactly the same regardless of whether or not the "sending unit" is connected or not. So, if what I have is really a temp switch then it works differently - it's a switch that stays "open" until a certain temp is reached, then it "closes" - it's an off/on proposition, not a variable resistance like a sending unit is. If that's what I really have, then that would explain what the gauge is dong. It sees an infinite resistance, which it displays as the coldest temp - all the time. The variance with RPM is probably just the voltage output from the alternator dropping and changing slightly as the motor idles and the cam makes it start loping. I think I can prove it maybe by robbing an old "volume control" out of something and wiring it so it provides a path to ground for the gauge - if I can make the gauge read that way and vary it by turning the knob, that'll pretty well prove it - at least that's what I'm thinking.

Bear
 

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Hey Bear, great to see you getting so close I am excited for you.

LOVE the vid. Can't wait for more updates. And hoping you get the electrical gremlins taken care of soon.

Scott
 

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Well, here's another wrinkle that's weird. I grounded the lead at the sending unit - no change. Disconnected it - no change. Then I noticed something... when I have the temp sending unit lead grounded, the GEN light on the dash is on solid, When I disconnect it, it's off. So I started tracing the circuit on my brand new color poster wiring diagram that arrived today, and what do I find? Turns out that on the plug that connects to the printed curcuit board behind the dash the lead for the temp gauge and the lead for the generator light are directly across from each other. They're also next to each other on the plug where the engine harness connects to the back of the fuse box. Ok, so tie that back to how my gen light was actiing with everything connected yesterday -- it started out dim then seemed to get a little brighter the longer I ran the motor - hmmm - just like it wouild act if it was connected to the resistor circuit that is the temp sending unit. Of course I'll probably have to pull the dash again to test my theory, but I'm beginning to suspect that those two leads are switched, either at the dash plug or on the engine harness/fuse box connection.

Bear
 

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Yes it would, wouldn't it? More evidence - when I turn on the ignition prior to starting the engine, the temp gauge pegs on the hot side --- just like it would do if it was shorted to ground. When the engine is started it pegs on the cold side -- just like it would do with an open circuit. The other weirdness I've been seeing with the GEN light is that it doesn't illuminate when I first turn on the ignition. I think the gauge is seeing the signals that should be going to the GEN light, and vice versa. More and more I'm thinking that these two leads must be backwards in the harness, and I bet it's at the plug that goes into the back of the instrument cluster because those two pins, #1 and #12, are both all the way down at the end of the plug. I betcha they're both plugged into the opposite side of where they should be.

Bear
 

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Bear, can you hook up an ohmmeter and verify the wiring issue without pulling the whole dash? Maybe fab up a couple of pin connectors/probes to see what you get at both ends of the circuit? I think you diagnosed the problem correctly, and you found the glitch. Now it's time to crawl back up under there and work on it.....yech.
 

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Yeee ha! It's all working now :cheers

Found the root cause of the problem which was...

Bear's an idiot... :eek:

Grab your favorite cool beverage, sit back, and I'll tell you the story.

My car originally had warning lights ajd a clock instead of gauges and a tach. Many many moons ago (really - more than 20 years) I bought a set of Rally Gauges and a factory in-dash tach for the car. When I was putting the gauges into my instrument cluster a week or so ago I'd noticed that there was something different about the speedo --- mine has the single "brake" warning light at the bottom but the one that came with the gauge cluster had two lights: a brake warning and a seat belt warning. Hmmmm... well, I looked everything over at the time and everything else looked just like my cluster, so I ignored that, swapped my speedo into the new cluster, and went on my merry way.

Then weird stuff happened as you've been reading over the past few days, and I eventually channeled Sherlock Holmes and arrived at the conclusion that the temp gauge and the gen light were wired backwards due to a defective harness, so all that was needed was to correct the wiring at the plug and things would be good.

This afternoon I pulled the dash enough to get to the plug and found.... everything was wired correctly, Say whut??? This cannot be! So I pulled the instrument cluster out of the dash and then got serious about really examining the traces on the circuit board, the plug, and everything.

Back when I was ordering parts for the dash, fortunately I also bought a new gauge circuit board thinking it would be needed. I didn't use it because the cluster already had one so why bother changing them? I sat down with the cluster, the new replacement circuit board, and really looked them over. Hmmmm... they're different. On the board that was in the car, that came with the "mystery cluster", the traces for the temp gauge and the gen light were in fact reversed from what they were on the board I'd bought. Aha!!! Then I started seeing other stuff. Like an extra trace where the 69 board didn't have one. The circuits for some of the lights were different, then there was that seat belt warning. :willy: I'd missed all those differences when I installed the cluster. ooops.... :eek:

So what I wound up doing was modifying the "mystery cluster" housing so that it would accept a single light bulb for the brake warning in the bottom center of the speedo slot in place of the two offset bulbs that had been there before, installed the correct circuit board, put it all back together - and everything is working now.

:party:

The temp gauge even seems to be reasonably accurate, very close to what my hand-held infrared meter shows when pointed at the thermostat housing.

Yay.

Well, at least I learned something about how the instruments work and feel like I understand this electrical stuff a little better now. :rolleyes:

Bear
 
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