New cluster did not fix the dead Gauge issues HELP

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Alright found some time to get under the steering wheel, upside down.

This is what I found out, if I turn the key to run (car not running), at the fuse box I am getting power to all fuses except the Instrument Lights fuse. I am trying to trace where the power comes into the fusebox for that fuse, I think it is Tan, but I can not tell where it is going?? without competely unwrapping the black tape everywhere.


Special note, I noticed (or had forgotten) the new Light switch I installed few months ago, has an additional ground tag on it that is not being used. You dont suppoes I need to ground that tab???

So what I know, power is not arriving at the Fuse box for the instrument lights.
Where to now?
 
Hold the phone I just got a huge woody. I went back outside to double check that I wasnt getting power at the fuse box WITH THE LIGHT SWITCH ON. None.... so I decided to fiddle with the fuse, as the fuse prongs are very rusty. And low n behold I have dash lights.
However they do not dim. They will go on if I turn dimmer all the way over, but as soon as I try to turn the dimmer down, lights go off.
Hummm....still no gauges working. But I am closer.
Ideas??
 
The dimmer is bad or real dirty. "Actively" twist the knob clear left to clear right several times, like, maybe about 10. If that does not fix it, you need a new light switch, or else put up with "where it works."
 
gdizzle said:
at the fuse box I am getting power to all fuses except the Instrument Lights fuse.
Click to expand...

I explained this earlier----------------

The headlight switch has TWO power sources

1---unfused power ONLY for the headlights, nothing else. There's a built in breaker for the headlights

2...The tail fuse supplies power TO the switch for tail / park / and DASH LIGHTS

....................So with the tail fuse working and the light switch on............

Power comes through the dimmer control and out ON A TAN WIRE. This wire goes DOWN TO the instrument fuse, that is, it is supplying power TO THAT fuse.

Through the fuse, and out on ORANGE wires, off to all the different dimmer controlled lamps
 
Replacement light switches cover later models that had the light switch mounted in plastic. That model would have a ground wire in its harness. Adding a ground wire in your application isn't required but cant hurt anything either.
 
^^And to clear that up further, the ground is for the dome light switch. Your door switches ground the yellow wire and complete the dome light circuit. Likewise, "twisting the knob" on the light switch activates that switch to ground.
 
OK update: I was able to ground out the Temp sender wire and got the temp guage to move.

So I have to assume that I am getting proper power from the cluster all the way to the temp unit on the engine. So I have ordered a new temp sensor since that is the only thing left to do, right?

Also another thing I am noticing, I can not get ground anywhere on the engine compartment, the only way I can get some ground is if I touch to the engine strap that is attached to the firewall.

Maybe because it is painted?
 
YUP There are at least a 1/2 dozen spots where fresh paint must be scratched to bare metal. I call that the devil in the details.
 
Uuggg. So replaced the temp sensor today, cleaned the connector female piece (attached to the sending wire), started her up, and nothing. No movement whatsoever on the temp gauge. Now I am at a loss.
Keep in mind this is what I have:
New IVR
New Cluster PCB
New Temp sensor

Gauge works when I ground it out, so we know power is getting from cluster to engine temp sensor. If I use Multimeter and check voltage at engine sending wire, I am getting fluctuating voltage.

What can I try next?
 
What do you mean "no movement" "started er up" The engine is cold? Did you warm it up?

You can also get an idea of how accurate the gauges are, as well as check the sender.

Check the sender cold with your ohmeter for resistance

Allow it to "just warm" up some and see how it changes. Warm the engine up "full temp" and recheck

Here are the sender resistances

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full)

These are same for oil, temp, and fuel. If you can get some resistors and make up these values, you can see if the gauges are at least close

EG you can (used to) be able to buy a pack of 4 1/2 watt, 100 ohm resistors at Radio Shack. Wire all 4 in parallel, and this gives you one 25 ohm resistor, which, when placed from a sender wire to ground, should give you 1/2 scale (midpoint) on the gauge.

Likewise, with the engine warmed to "normal" temperature, the sender should READ somewhere in the probably 35 ohm to 20 ohm range or so.

It is possible, if you over-tightened the sender, that you damaged it.
 
I warmed it up for 15 minutes and the gauge never moved. Do I test the sender unit by removing it from the block and checking it???

I get lost when you talk about resistors and Radio Shack is completely useless now. All they do now is sell cel phones.
 
OK, you can order resistors from people like Mouser electronics or Digikey. They are easy to work with. How big is your city / town? Find a local amateur radio operator "ham" or other electronics hobbyest.

No you can just leave it right there in the block.

When absolutely cold, and depending on ambient temp the sender will be 73 ohms or more

When at "normal temp" it will be somewhere in the middle, depending on temp

When hot, which you can only check by putting it into boiling water, etc, and checking it "right away" it will be down towards lower resistance.

But anything in th 30 ohm--20 something should give you a "mid gauge" reading.

"Somewhere" on the internet is a chart showing resistance vs temperature. It's a thermister in there
 
ohms meter... 1 probe on top of sender ( wire removed ), other probe on hex shaped base of sender. Should show about 80 ohms. Then move the that probe to negative battery post. Should also be close to the same 80 ohms. Sender must have a ground path back to the battery. Too much Teflon thread tape on the sender could interrupt the path. Too much paint in the intakes threads too.
If all the tests prove out the gauge is bad. Most have the conception that ground the wire and gauge moves means the gauge is good. Not true. There is a bimetal strip or beam in there that bows when heated and moves the needle. If that beam and/or the winding on it is toasted, a zero resistance test can create heat that causes needle movement where a senders resistance cannot. Hope this helps
 
ok so it says I a getting 70ohms with the testing of the sender wire and base of temp sensor (wire removed), then move that probe to -battery terminal, stays the same 70ohms.

That doesn't seem like a significant decrease from the 80ohms that you expect. Does it?

Whould that cause gauge to not move at all?

Is everything now point me to the gauge as being burned out? Or is it still possible that the gauge is not getting ground on the cluster? but all the little dash lights are now working.

Fuel gauge still dead as well.
 
70 is close enough. Now you need to start the engine, let it run atleast 10 mins. Check sender again.
As thermostat opens we would want to find 34 ohms. Anywhere between 40 and 20 should put the needle somewhere in the normal operating range.
 
ok I tried to do this while it was running. Is that right? I was getting screwy readings jumping from 20 to 70 back n forth and crazy stuff.
I started engine let it run, then disconnect sender wire, took multimeter and stuck it into the sender wire then the other lead went to the ring around the sender unit. While it was running. Was I supposed to turn it off?
 
off after hot would have been easier. One probe on neg' batt' terminal would have been easier too. Since heat rises or reading may have been a little different when water flow stopped. Anyway.. If you saw a steady 20 ohms reading you have a bad gauge. All over the place readings suggests a intermittent break in ground connection that isn't present when the engine is still/off. Another one of those rare faults I've seen before. Vibration combined with loose hardware or a wire broken inside the casing ( or under electric tape ). Years ago a guy had all sort of charging system issues in his Nova. I noticed a gob of electric tape where batt' ground cable attached to block, gentle tug on the cable pulled it right out of the terminal under the bolt.
So if you want to try again, run it till hot, shut it down, check sender reading. See a steady 40 to 20 ohms, put the sender wire back on and turn ign' switch to on.
 
ok good. I ran it and drove it for 15 minutes, then shut it off. Temp was close to 200 on radiator with my infared temp gun.
I removed sender wire, put multimeter lead in it then touched other lead to the shoulder of the sensor unit, steady 70ohms. which means there was no change when it was hot or cold. Also moved lead to battery post and 70 still remained. So what does that mean? this is a brand new sensor.
 
Brand new doesn't mean squat today. Even a nearly new one that was working yesterday might not work today.
Oil senders suddenly leak oil. Temp senders die like light bulbs ( don't drop it ). Nature of those beasts.
 
I wonder if you have a ground strap on your fuel sending unit. Also, like was said before, if you used Teflon tape on the sending unit, it can keep it from grounding.
 
67Dart273 said:
You can also get an idea of how accurate the gauges are, as well as check the sender.

Check the sender cold with your ohmeter for resistance

Allow it to "just warm" up some and see how it changes. Warm the engine up "full temp" and recheck

Here are the sender resistances

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full)

These are same for oil, temp, and fuel. If you can get some resistors and make up these values, you can see if the gauges are at least close

EG you can (used to) be able to buy a pack of 4 1/2 watt, 100 ohm resistors at Radio Shack. Wire all 4 in parallel, and this gives you one 25 ohm resistor, which, when placed from a sender wire to ground, should give you 1/2 scale (midpoint) on the gauge.

Likewise, with the engine warmed to "normal" temperature, the sender should READ somewhere in the probably 35 ohm to 20 ohm range or so.
Click to expand...

Good stuff. Thank you. I wish I was more thorough when my '65 panel was out. Certainly could have bench checked the panel and gauges more thoroughly out of the car.

Add in a couple so-so grounds, some corrosion at the bulk head connector,...

The ground side seems like step one. Battery to block, block to firewall. Hard ground the IP to chassis (vs. panel screws). Tail light housings to body.

I am living with my turn indicators, for now.

If the sender(s) wires were picking up resistance (or open/ loose connection) at bulkhead connector, possibly affect gauge reading?
 
Ok so I broke down and got a mechanical temp gauge and hooked it to the radiator.

I did test the temp sensor while car was hot, and disconnecting it and using multimeter on it shows me about 23ohms . Which sounds about right. Seems like I am getting continuity and no resistance problems. Just the guage is DEAD. no motion. As I mentioned before, I can get it to move if I ground it out, it gets shaky. But sounds like it still must be dead. right? Any other ways to get it working again?

Now onto the Fuel sensor. I already tested the gauge outside of the car. It works, smooth. So now to find out where it isnt working.

Is it at all possible that the new Voltage Limiter is not working? Or is incorrect? Would anything else not work other than the Fuel and Temp gauge if the voltage limiter is bad?
 
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