I think I broke something . . . but it doesn't make sense (66 Newport)

darth_linux

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So, last weekend while I had the panel that lives under the steering wheel removed so I could install my tachometer, I thought I'd try installing one of my LED bulbs in the instrument cluster. I reached up to unscrew the nearest light socket, pulled it out, put the LED in, screwed the socket back in and turned on the dash lights to see what it looked like. Nothing. I thought the orientation might be off so I pulled it out, reversed it, plugged it back in, turned the dash lights on again. Still nothing. Perplexed, I put the original bulb back in and went back to installing the tach.

After getting the tach installed, I was ready to start the engine. Turned the key to "on" and noticed that the OIL light failed to light up. Turns out this is the bulb I had been swapping out. Started the engine, checked the tach, everything seemed in order except no OIL light with engine stopped and key ON. I went under the hood and checked for voltage at the sending unit to see if it was just a bad bulb. Then I was really perplexed because there was no voltage getting to the sending unit anymore. I posted a question on this forum, futzed around with the test light, couldn't find the correct wire at the bulkhead because a PO had painted absolutely everything with a thick coat of black paint. Decided it wasn't worth continuing on with at the moment, and mentally postponed the examination until summer.

THEN I noticed that my fuel gauge wasn't doing anything anymore either. It wasn't reading correctly before, but at least the needle moved. Now, the needle is pegged on E and doesn't budge no matter what.

Today I had the car up on a lift and I checked for voltage getting to the fuel tank sending unit - nothing. I cleaned off the ground strap real good, also wire brushed the metal fuel line and noticed that the sending unit looks to have been replaced in the last 5 years or so. Replaced the ground strap and checked again - still nothing coming to the tank.

SUMMARY - I changed out and replaced back to original the OIL light in the dash and now the OIL light doesn't work anymore and neither does my fuel gauge. No voltage is getting to either sending unit. What could I have done?

TIA
 
My guess is you disturbed the wires back of the cluster.
Check fuses first.

The gas guage runs on 5 volts. There is a voltage limiter on tge back of the cluster that takes 12 volts in and 5 out to the guage.
5
TYpically a black wire feeds the limiter and works only with the key on or AAC.
Test the feed to limiter and then power goi g out of it.
Another possibility is the printed circuit board that the bulbs gointo is no good.
Hope this helps.
 
My guess is you disturbed the wires back of the cluster.
Check fuses first.

The gas guage runs on 5 volts. There is a voltage limiter on tge back of the cluster that takes 12 volts in and 5 out to the guage.
5
TYpically a black wire feeds the limiter and works only with the key on or AAC.
Test the feed to limiter and then power goi g out of it.
Another possibility is the printed circuit board that the bulbs gointo is no good.
Hope this helps.
Yeah, I'm thinking I'm going to be removing the cluster in the near future to change out all of the bulbs, replace the Voltage Limiter and/or fuel gauge itself, and attend to any other weirdness I find. Not really looking forward to it . . .
 
Yeah, I'm thinking I'm going to be removing the cluster in the near future to change out all of the bulbs, replace the Voltage Limiter and/or fuel gauge itself, and attend to any other weirdness I find. Not really looking forward to it . . .

I feel yer pain

Old Lady Eating Popcorn -2.jpg
 
I’m gonna send in the bore cam to take a look for anything unusual. Plan to pull the cluster over my summer break…
 
That cluster comes easier than you think. I can get one out in about half an hour. RT Engineering makes a good solid state 5V regulator that plugs into your board.

The "Big Trick" to removing the instrument panel and board in a '66 is to stand on your head, with that right under your steering column, and with everything properly loose, ROTATE THE WORKS AROUND THE STEERING COLUMN, just as told in the FSM. the 1966 FSM is the best written of the whole lot, so you will have good, detailed instructions to follow.

We want another '66 Chrysler, which is why we're keeping Mathilda's relics. I learned A LOT driving ours for 5.5 years, until her murder by an insurance fraudster. They're still our FAVE C body: rugged, simple, beautiful.
 
That cluster comes easier than you think. I can get one out in about half an hour. RT Engineering makes a good solid state 5V regulator that plugs into your board.

The "Big Trick" to removing the instrument panel and board in a '66 is to stand on your head, with that right under your steering column, and with everything properly loose, ROTATE THE WORKS AROUND THE STEERING COLUMN, just as told in the FSM. the 1966 FSM is the best written of the whole lot, so you will have good, detailed instructions to follow.

We want another '66 Chrysler, which is why we're keeping Mathilda's relics. I learned A LOT driving ours for 5.5 years, until her murder by an insurance fraudster. They're still our FAVE C body: rugged, simple, beautiful.
I did take a peek with the bore scope camera and discovered I had screwed the lightbulb into the turn signal socket rather than the oil light socket. I moved it back and checked again, and the oil light still does not light so there’s definitely something else going on.

I’m gonna wait until the weather warms up a bit more before I take the plunge and pull the cluster out. I need to lubricate the speedometer cable at the same time, your recommendation on the best lube is appreciated.

I also need to take apart the odometer and see if I can get that working again or find a place to send it out to for repair. Does anyone repair these things or do you just change out the odometer from a known good unit?

When I have it all apart, I’ll clean the contacts, I’ll check for bad grounds, replace the voltage limiter, and put in LED bulbs throughout.
 
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Last spring, I could not find a convenient source for speedo cable lube, so I made some. I mixed ATF and powdered graphite to a creamy (albeit black!) consistency. This worked well all season, but time will tell if it will work in the long run. Lindsay
 
any time i find i need to do any work under the dash that might take some time i find it easier to take the front seat out. usually only 4 nuts to remove from underneath and out comes the seat. it will save your back and you will no longer have to be a contortionist to get **** done. than you can just put a blanket down or a sleeping bag to lay on. it will save your back. trust me on this one. cheers
 
Today I had the car up on a lift and I checked for voltage getting to the fuel tank sending unit - nothing. I cleaned off the ground strap real good, also wire brushed the metal fuel line and noticed that the sending unit looks to have been replaced in the last 5 years or so. Replaced the ground strap and checked again - still nothing coming to the tank.

TIA
There is not supposed to be voltage at the sending units; that’s not how it works. The voltage is supplied to the gauges, via the 5v limiter. The sending units send a varied resistance to ground signal to the gauge. You should never see any voltage at the sending units.
 
...ATF and powdered graphite to a creamy (albeit black!) consistency. This worked well all season, but time will tell if it will work in the long run. Lindsay

I used Lubriplate break-in grease w graphite for my steering column. Need the graphite for some conductivity.
 
I did take a peek with the bore scope camera and discovered I had screwed the lightbulb into the turn signal socket rather than the oil light socket. I moved it back and checked again, and the oil light still does not light so there’s definitely something else going on.

I’m gonna wait until the weather warms up a bit more before I take the plunge and pull the cluster out. I need to lubricate the speedometer cable at the same time, your recommendation on the best lube is appreciated.

I also need to take apart the odometer and see if I can get that working again or find a place to send it out to for repair. Does anyone repair these things or do you just change out the odometer from a known good unit?

When I have it all apart, I’ll clean the contacts, I’ll check for bad grounds, replace the voltage limiter, and put in LED bulbs throughout.
Replace the cable.
 
There is not supposed to be voltage at the sending units; that’s not how it works. The voltage is supplied to the gauges, via the 5v limiter. The sending units send a varied resistance to ground signal to the gauge. You should never see any voltage at the sending units.
Is voltage supplied to the idiot lights in the same way as it is sent to the gauges?
 
When I was evaluating LEDs in a 65-66 cluster (here), I found that the bulb sockets were VERY finicky about how much to twist them vs the LED working. And the polarity, too, of course.
 
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