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| [GMCnet] Erratic Turn Signals [message #272550] |
Tue, 24 February 2015 11:05  |
Afastchief
Messages: 9
Registered: October 2011
Location: King NC
Karma: 0
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Junior Member |
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I have a 1978 Royale and the turn signals have started acting erratically.
They will work slowly one minute and then stop, or one side works slowly and
the other not at all. The flashers do work and all bulbs are good. It seems
to me like a possible bad ground somewhere does anyone have any insight?
Thanks so much,
Alan
Alan Edmondson
2501 YMCA Camp Rd
King, N.C. 27021
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Alan Edmondson
King, NC
78 Royale, engine bay insulation, dual cockpit fans, Victron 160A isolator, Yandina combiner, Victron BMV 700 battery monitor with Bluetooth, Progressive Dynamics 9200 converter
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| Re: [GMCnet] Erratic Turn Signals [message #272567 is a reply to message #272550] |
Tue, 24 February 2015 16:01  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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The standard turn signal flasher in the GMC works on the current draw through the turn signal lamps. Too little current (low current because a lamp is not functioning) will make the flasher go slow or not at all if the current is too low.
When you experience a slow or no flash, with the turn-signal ON, check for any inoperative turn-signal lamps. The malfunctioning lamp can be caused by a poor connection anywhere in the circuit, both on the power side and the ground side. Since this happens randomly, you have the fun of tracing an intermittent connection. The best time to troubleshoot is when the turn-signals are not working properly... is difficult to fix something that is working!
Check the faulty bulb for poor contacts on the bulb and socket and grounding of the shell. The lamp filament can also be intermittent, have a known good bulb handy for substituting.
The flasher may also be faulty (burn't contacts).
Good luck!
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Erratic Turn Signals [message #272574 is a reply to message #272550] |
Tue, 24 February 2015 17:37 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Afastchief wrote on Tue, 24 February 2015 12:05I have a 1978 Royale and the turn signals have started acting erratically.
They will work slowly one minute and then stop, or one side works slowly and the other not at all. The flashers do work and all bulbs are good. It seems to me like a possible bad ground somewhere does anyone have any insight?
Thanks so much,
Alan
Alan,
Welcome to the group, family, cult, asylum....
As Bruce mentioned, the signal flasher is current sensitive.
Just for giggles, turn on the parking lights and then the four ways. Now walk around and see if one of the four is flashing out of sequence. That one has a bad ground. That maybe today, give the others a chance and they will do the same.
Here is the gatcha...
If a bulb ground goes bad, it will still flash, but it is the wrong filament that is flashing. This can get you the slow flash.
Because this situation can change with the heat of the bulb, it will seem almost random. That is what leads me to the bulb sockets.
Here is the fix if I am correct.
I could tell you how to find the one (if there is only one - slim bet), but it is just not worth the effort because even if you find the problem bulb today, chances are tomorrow will be another and this is less work to do than it is to write about it.
First - find some dielectric grease. Most autoparts stores will have it. This is really kind of a misnomer. All greases are dielectric, but this type of silicon based grease has ZERO flim strength. So, where a good grease would actually keep metal parts from making contact this stuff will not.
Second - get some of the what ever is the generic name for Scotchbrite. You need a flexible abrasive.
Third piece is a stick or dowel (not fussy). I have forgotten if I like a 1/2 or 7/16 better for this job, but it doesn't really even have to be round.
To do four times:
Remove the lense,
Remove the bulb,
Polish the bulb with the Scotchbrite until it looks nice.
Push the Scotchbrite into the socket and work it around until it look pretty good.
Coat the base of the bulb with the grease and put it in. (Now get a paper towel and try to get the grease off your hands and the bulb.
Do not reinstall the lens yet.
Repeat.
When all four are done, go back and do the 4-way and marker trick again and make sure that they are all good.
Did we get it??
This is a very common issue with old vehicles.
If we didn't get it, there is another common mode failure.
This is occurs when the socket has lost contact with the reflector. The light counts on this contact for the ground. It is not often that this is random. If you suspect this, take a skinny straight screw driver and a couple of feet of wire with the end stripped. Hold one end down on the bumper (some days I miss chrome bumpers) and with the other end held to the screwdriver shank, stick the point of the driver up against the visible portion of the bulb base. If that got it, you have narrowed your search. Try the same trick to the exposed edge of the socket. You may have to run a jumper between the socket and the contact on the reflector.
If this doesn't fix you, come back and we can go deeper.
This is you first post here. I don't know if you are a recent owner, but I want to welcome you. You are now a part of a community like very few others. It is a helping sharing group and as of today, you have about 2000odd old friends. I liken this group to that of the watermen that are my world. Because of that I like to welcome new owners here much as a new owner or vessel would be welcomed there. So,
May the Good Lord bless this coach and all those that set forth within her.
Welcome Alan
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Erratic Turn Signals [message #272585 is a reply to message #272580] |
Tue, 24 February 2015 20:52 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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While the flasher is current sensitive, the current is VOLTAGE SENSITIVE! If the alternator is not keeping the system voltage up to to the proper level, this is exactly what will happen. Almost didn't get my driver's license because of this. The road test observer had to make sure the turn signals worked on my dad's 67 Olds, and they didn't flash for her! I was the last test of the day (my 16th birthday), and now it wouldn't pass inspection! Went back to my dad with the problem and he said "The alternator pulley is larger than the original one so it doesn't charge as much at idle, so just raise the engine rpm about a hundred or so and they will flash fine." And he was right. One of many lessons learned through experience. 
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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