A2 - Erratic Turn Signal Blinking

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A45WV
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A2 - Erratic Turn Signal Blinking

Unread post by A45WV » March 3rd, 2022, 11:48 am

I've got turn signals both directions, but the blinking is erratic. Example: I'll get 2-3 blinks...then a pause....then one blink....then a pause....then 4 blinks, etc. My first thought was a problem with the flasher unit. Any other ideas or troubleshooting suggestions?

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rickf
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Re: A2 - Erratic Turn Signal Blinking

Unread post by rickf » March 3rd, 2022, 12:06 pm

My first thought would also be the flasher unit on the floor. You should have the electronic unit and they would tend to either fail completely or work right. I would first check for a good ground at the flasher unit and check the connections from the unit to power and to the flasher on the column. The flasher on the column could also be the problem, What you can try there is to simply run the flasher back and forth, back and forth ten or fifteen times and this should clean off the contacts in the unit.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Hambone
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Re: A2 - Erratic Turn Signal Blinking

Unread post by Hambone » March 3rd, 2022, 6:44 pm

If it turns out to be the flasher, there are some knock offs out there, spend the few extra bucks and get a NOS or tested T/O, the $50 ones you see are probably from China. Don't remember where I seen the post but some rigged up one from the parts store.

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Re: A2 - Erratic Turn Signal Blinking

Unread post by Sledge303 » March 3rd, 2022, 11:39 pm

You may also want to dismount the tail light housings and clean the contacts that ground it to the body.
My MUTT had been painted and some contact points were coated and not working.
I also added "star" washers to the mounting bolts to get a good bite into the metal and solid grounding.
Looking inside the brake lamp housings you will see that more than one ground point is used, its circuit dependent.
It may resolve this, and certainly can't hurt the tail lamp operation in general.
Sometimes current seeking a ground will find and unintended path and cause unexpected behavior with the lighting.
Sledge
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Mark
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Re: A2 - Erratic Turn Signal Blinking

Unread post by Mark » March 4th, 2022, 12:05 am

Several circuits are independently grounded to keep several circuits working independently so if you lose 1 ground point, the other circuits will keep working, is my theory of operation
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1981 m151A2
1964 m416
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Re: A2 - Erratic Turn Signal Blinking

Unread post by svramselaar » March 4th, 2022, 6:56 am

hi

i think it is the flasherunit
there is a three wired plug at it
take it of and put wire A and B together
now the lights must be working with no flash
if so unit gone
i do not know if you can open it there is probbely a solder point open
if there is go power over solder melts light go out and the solder cools down and make contact again and so on
the ground for the unit is at the left inner fender bolt same as alternater and left headlights

george

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Re: A2 - Erratic Turn Signal Blinking

Unread post by A45WV » March 14th, 2022, 12:50 pm

svramselaar wrote:
March 4th, 2022, 6:56 am
hi

i think it is the flasherunit
there is a three wired plug at it
take it of and put wire A and B together
now the lights must be working with no flash
if so unit gone
i do not know if you can open it there is probbely a solder point open
if there is go power over solder melts light go out and the solder cools down and make contact again and so on
the ground for the unit is at the left inner fender bolt same as alternater and left headlights

george
I finally got around to working on troubleshooting this issue over the weekend. My Navy Fire-Controlman son (better with a multimeter than me) and I have concluded it's the flasher unit. Using all of the info here, the assessment came down to using George's technique to test the flasher--and jumping the A-B pins yielded a solid "on" condition for the turn signals (both front and rear).

Unless someone has better guidance, I'm thinking a NOS or tested take-off flasher unit is the best option to fix?

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Re: A2 - Erratic Turn Signal Blinking

Unread post by Bonica » March 14th, 2022, 8:01 pm

Good idea!

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Re: A2 - Erratic Turn Signal Blinking

Unread post by rickf » March 14th, 2022, 8:06 pm

Yup, unless you want to convert to civilian truck style flasher which looks just like a regular car version. I have a ton of those that came with a lot of military stuff I bought. I would suggest going with the original unit though. I have at least one used one and I know I have several NOS ones but getting to them could be a problem.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: A2 - Erratic Turn Signal Blinking

Unread post by A45WV » March 26th, 2022, 5:24 pm

Flasher unit replaced with a tested take-off unit. I now have blinkers that blink properly! Thanks to everyone.

One other issue--I've never had tail-lights on this vehicle when the headlights are on. I have always had brake lights, and now consistent turn signals, but have never had tail lights in service drive. I looked at all of the connections and ground(s) yesterday and everything looks normal. Bulbs are all fine. I'm beginning to think it's either a) a problem with the composite tail light units themselves; or b) a problem with the multi-switch light control in the dash. Anyone have any ideas?

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Re: A2 - Erratic Turn Signal Blinking

Unread post by Mark » March 26th, 2022, 5:53 pm

Is the wire feeding tail lite hot?Then is the inside the bulb socket hot?My answer might be too primitive!
mark


1968 m274A5
1960 m151
1981 m151A2
1964 m416
1971 m416

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Re: A2 - Erratic Turn Signal Blinking

Unread post by csmith » March 26th, 2022, 6:06 pm

A45WV wrote:
March 26th, 2022, 5:24 pm
Flasher unit replaced with a tested take-off unit. I now have blinkers that blink properly! Thanks to everyone.

One other issue--I've never had tail-lights on this vehicle when the headlights are on. I have always had brake lights, and now consistent turn signals, but have never had tail lights in service drive. I looked at all of the connections and ground(s) yesterday and everything looks normal. Bulbs are all fine. I'm beginning to think it's either a) a problem with the composite tail light units themselves; or b) a problem with the multi-switch light control in the dash. Anyone have any ideas?
Ask George, he is the man when it come to electronics!
1976 M151A2 4 Color Cammo Mutt, aquired August 09
1976 or 7? M151A2 "Miss Sandy" Driver, aquired May 2010
Former owner M151A2 "Miss Saigon" Vietnam Rescue Sold Sept 09
Fond appreciation for the M151 Breed!!

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Re: A2 - Erratic Turn Signal Blinking

Unread post by Bonica » March 26th, 2022, 6:07 pm

Swap out switch.

Fil Bonica

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Re: A2 - Erratic Turn Signal Blinking

Unread post by A45WV » March 26th, 2022, 6:44 pm

Bonica wrote:
March 26th, 2022, 6:07 pm
Swap out switch.

Fil Bonica
I will do this--as I have a new one ready to go post painting. Will follow-up when installed. Thanks!

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Re: A2 - Erratic Turn Signal Blinking

Unread post by rickf » March 26th, 2022, 10:03 pm

If the headlights are working then the service drive mode is working and the tail lights should be working. Before changing the switch I would check the connection on the each of the wires coming into the light back at the light. If you have power there then check the center of the socket for power and if power there you have a bad ground from light to body. If the first test shows no power move back to the connectors behind the dash and make sure there is, or is not power there. If not then you can go to the switch. One thing you can try if you suspect the switch is to hold your lock out over and repeatedly run the mode switch back and forth through the whole rand 10-15 times. These switches are designed so that the contacts are self cleaning and that will clean all of the contact from one end to the other. Might even want to try that first since it takes little time and it will do not harm to do it. If it works then it was a simple fix. If it does not work and you have no power in the wires then the switch should be replaced. I am a firm believer in diagnosis before replacement. I hate to see good parts get thrown out. When I had my shop my reputation was built on thorough diagnosis of problems before spending money on parts.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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