Left Side Signals Inop - Help?

[orfunauto/Darrell]

74 MCI8 problem:  This past weekend I had an occasion to have to run my four way emergency flashers for an extended period of time.  While they were on, I could hear the flasher working, but when I looked down at the tell-tale indicator, I noticed that the indicator was not flashing.  I looked out at the side mirrors and noticed the lights were not on or flashing.  I turned the emergency flasher switch off, flipped the left signal on and the lights still didn't flash, even though I could hear the flasher working.  I then flipped it to the right side signal and they worked!???!
 
So far, I have checked the terminals in the front junction box and found that terminal stud #'s 6 & 7, code 44f & 44r do not have current going to them - and I believe they should if the left signal is on.  The right signal terminals #"s 8 & 9 have current going through them when the signal is activated.  This, I believe, would tell me that the flasher is working properly because it's getting it's request from the signal light switch and "flashes" (audible flash) in both the left and right positions.  All left side bulbs were changed out - no difference -

What's my next move?         

[NJT5047]

OHHH..the dreaded wiring gremlins!   
I agree with your conclusion.  FJB studs 6 and 7 should see flashing power when the turn LH turn sig is on.
My best guess would be a short in the steering column, or lead 44...from the steering turn signal unit out leads.
Check for power on the "hazard warning" switch.  That will help isolate the problem. 
A short would cause the flasher to "work" or sound like it's working. 
If you don't have flasher power at the haz switch, the problem is between the haz switch and the steering column signal switch.  If you find power at the haz switch...you get the picture.
Have you worked on the steering?  Or replaced the steering wheel?  I'd check the wiring all around the area where it exits the turn signal switch and runs into the dash. 
That's an area where loose wires can be caught by feet.  You may not have done so, but the previous owner may have repaired the wiring in the steering column. 
May wish to look for any areas of related wiring that have new (newer?) tape wrapped.  There's your problem if you find repairs to the wiring.
The only other idea that I could offer would be to disconnect both the rear and front TS leads from studs 6 and 7, and see if the flasher quits working.  If so, you could have a short in one of the TS leads and power is taking the route of least resistance.  If you're using a test light, it may not 'see' the pulse.  A DVM would.  I'd still place me bet on the steering signal switch and wiring.  If you find this to be the case, hook up either lead and see which one may work.  Rules out the good wiring.  Another way to rule out wiring
I just finished installing two new 8ds.  I'm getting too old for this.  Turned on the fridge so that it could cool down.  I reckon we're heading over to the FMCA rally at Fleetwood Resort on Friday.  Generally have the bus up here at the house and washed and ready to go. 
Not this week...running way behind at work!  Oh well...better than starving? 
Hope it starts.  Always has.  Nice to 12.8 on the battery meters again.
Reckon these Sam's Club batteries are any good?  I'll definitely let everyone know!
Best, JR

 

[Stan]

I don't know if there is something different about an MCI-8 signal light system, but in the normal system the signal light switch assembly has a left and right switch. Current flow is through the  switch, through the flasher, to the light bulb.

[Ednj]

Pull off the left front side light and check the ground

[Hartley]

It is possible that your 4-way switch is simply bad.

It may be a double pole double throw switch and just that simple and cheap.

I would suggest changing the switch first.

Generally they are wired so when the 4-way is on the flasher line is tied
to both left and right terminals. and when Off the terminals are rerouted to
the manual left/right switches.

That is how my MC9 is wired, I suspect that yours is also.

It's worth the $5 to change the switch first.... Might be just that simple...

Dave.....

[orfunauto/Darrell]

FOUND IT! 

I took the signal light switch off the column, disassembled the cover, and checked continuity on the two micro switches.  The left turn switch is bad....  I believe I can replace that switch only, instead of replacing the whole assembly.  I'll let you know how it turns out.