Turn Signals & Gauge Failures

[Black and Blown]

Hi everyone.  I took 2 years of auto mechanics from the great Dale Karsky back at Milbank High School in the '80s, but we didn't get much into troubleshooting wiring.  I've been around Chargers long enough to know their reputation for wiring failures, but frankly, I don't know jack about wiring.  I'm hoping one of you might bail me out with some know-how.  Here's what's going on:
I started the 1970 Charger the other day, drove to the corner - and my turn signal didn't work.  I drove on, and they worked fine at the next corner.  Later in the same drive, my water temp and oil pressure gauges fell to zero (fuel gauge not hooked up at all since I have a fuel cell in the trunk), and once again the turn signals stopped working.  I've driven the car three times since then, and it's happened each time.
More info:
I recently had the ignition switch replaced. (like 100 miles ago)
The brake lights don't appear to be affected - they still work, even when the turn signals don't (except only the opposite brake light comes on while the turn signal is selected).
Since this started, I also replaced the battery, as that was shot.  Replacing the battery didn't fix the problem, regretfully.  :-)
Does this sound familiar to anyone?  Any advice/direction?  Thank you for reading.

[XH29N0G]

First, nice looking car.

Unless the whole cluster failed, I think you might be looking at two different things, but both might be related to a connection that is intermittently good and then shakes loose or heats up and gets loose.

The falling of the gauges to zero could be a connection on the back of the cluster, and I think it is possible it could be on the side that is ground.  I believe they all use a common ground.  What I find puzzling, is that I think the gas gauge may share that ground.  If this was the only time, I would wait to see if it repeats, and if so, then trace that circuit.  Unfortunately, I think you are going to have to train yourself to trace the circuits with something like a multimeter.  Second, I would consider looking at the diagrams in the faculty service manual and seeing if you can trace some from place to place.  The reason is simply that it is the way to learn how to troubleshoot these things. 

I also suspect it is a connection with the turn signal.  I could guess it could be something in the switch, in the wiring from the column to the harnesss, maybe at the flasher for the turn signal, or maybe at some other connector.  Intermittent problems can be difficult. Again, if you have a multimeter (and I would strongly recommend getting one), you can learn how the system looks when it is working and then quickly check it when it stops working.

There are others on here who know a whole lot more than I do.  They will sign on and may have more specific things to test and look for.  What I wrote might get you started though.

[Black and Blown]

Thank you.  I agree - I need to learn wiring!  No getting around that. 
I edited my first post as I left out the part about having a fuel cell in the trunk - the fuel gauge is not hooked up.  I am convinced that we have one issue here that is causing both symptoms, as they only occur simultaneously.  For what that's worth.  Thank you again! 

[XH29N0G]

If they occur simultaneously, and assuming there other things that also cut out, you might be looking at something that is common to all these circuits.


Just to keep this straight.  When the turn signal goes, there is no reading on temp and oil pressure, but the engine continues to run.  Are there other things stop working?  Someone on here will know.  If I think of something or figure something out, I will post.

[Black and Blown]

I don't know of anything else that dies - I haven't tried the headlights, and the car doesn't have a radio.  The car runs fine, as the EFI is wired separately.

[HANDM]

Turn signal switch....

[Black and Blown]

UPDATE:  A couple days after posting this, it occurred to me that I should describe this phenomenon to the mechanic who installed the ignition switch.  When I did, he described how he had problems getting things to work after installing the ignition switch.  In response, he tweaked the terminals where the switch connects (on the switch side), and things worked.  He suggested that this was most likely the cause of the problem.  I brought it in, and he did additional tweaking on the receiving side terminals, and I haven't had the problem since.  My takeaway is:  Don't buy this brand of switch in the future.  I bought the part at Sturdevant's, which I think of as reputable, but I'll be more discriminating in the future.  Thanks guys!