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willysmjeeps.com :: View topic - 56 M170 headlights not working
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56 M170 headlights not working

 
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iwojimavet
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Joined: May 30, 2011
Posts: 17
Location: St. Louis, MO

PostPosted: Thu Sep 13, 2018 9:36 pm    Post subject: 56 M170 headlights not working Reply with quote

Both headlights went out at same time while driving. All other lights (convoy/blackout) still work. I pulled the light switch box out, cleaned the connections and screwed it on back tight. Still no go. I got the wiring diagram and know where to look, but I am afraid I,m a novice electrician and donít know how to check th grounds and the connections. Do I just turn the battery switch on and the headlight switch and hold the meter positive to the ends? Sorry, I have no clue.
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wesk
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Joined: Apr 04, 2005
Posts: 13877
Location: Wisconsin

PostPosted: Fri Sep 14, 2018 1:01 am    Post subject: Reply with quote

It would take 10 paragraphs or so to guide you through a safe troubleshooting effort here. This is where you do some U-Tube research on how to use a VOM, how to troubleshoot electrical circuits and how to inspect and repair bad grounds. Get some of that under your belt first then post for some local help from a restorer in your neighborhood.

I am not trying to avoid your request. I am trying to avoid leading you into a mishap and a lot of smoking wires. 24 Volts will burn up wiring twice as fast as 12 volts will.

When you said you
Quote:
I pulled the light switch box out, cleaned the connections and screwed it on back tight.
Did you actually remove this?



And opened it up and cleaned the contacts?



or did you just unscrew the plug, clean the pins and screw the plug back on?

Which switch do you have. One of the three above?
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

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iwojimavet
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Joined: May 30, 2011
Posts: 17
Location: St. Louis, MO

PostPosted: Fri Sep 14, 2018 8:03 am    Post subject: Reply with quote

Thanks for the info, and will do. I just cleaned off the pins. I'll take it apart and clean the contacts. Thanks for the help. After reviewing Youtube, I'm sure I'll come back for more questions. I see where the headlight wires meet up, just don't know how to test them at that point.
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iwojimavet
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Joined: May 30, 2011
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Location: St. Louis, MO

PostPosted: Fri Sep 14, 2018 8:04 am    Post subject: Reply with quote

My lightswitch is the late model on the right
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wesk
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Location: Wisconsin

PostPosted: Fri Sep 14, 2018 11:03 am    Post subject: Reply with quote

They are sealed, non-repairable, throw-aways. No parts or instructions are available for them. The two Bendix models are repairable, rebuildable and instructions are in TM 9-1825E (the excerpts are on our downloads pages).

The best way to trouble shoot these switches is with a test pigtail. You find an old cannon plug that matches the pin size, arrangement and attach wires to each pin that the original plug has wires on. You do this by studying the Pinout Illustration in TM 9-1825E.





I would go one step further and build a small breakout box with a test lamp for each circuit and a long enough harness to reach behind the dash, unscrew the cannon plug and screw my test set plug on and lay the breakout box on the driver's seat. Then apply 24V to wire #15 Pin Letter F. Now just place switch lever in each position and observe that correct circuits are powered up.

In a motor pool the switch being a common stock item they would simply unscrew the plug from the old switch and screw it on the new switch and check vehicle lamps for proper ops. Great if you have a few new in the box switches to do that.
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

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Stiknruddr
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Joined: Jul 28, 2017
Posts: 40

PostPosted: Sun Sep 16, 2018 12:54 pm    Post subject: Headlights Reply with quote

Fyi if you are running 12v and have the later 3 lever switch itís probably got a 20 amp circuit breaker inside. I removed it jumpered it put a in line CB. Also ran a 12 ga dedicated power power wire to the switch input. My headlights were suddenly going off like yours.
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wesk
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Joined: Apr 04, 2005
Posts: 13877
Location: Wisconsin

PostPosted: Sun Sep 16, 2018 2:30 pm    Post subject: Reply with quote

That's a good point to bring up. trigger's several questions.

1 - Is you jeeps 24 volt electrical system stock & in tact?

2 - These Bendix switches were discontinued mid production on the M38. The M38A1 & M170 never had them but they will function in your jeep but will need an external circuit breaker or fuse. The Bendix switches will function just fine using 12V or 24V input on wire #15 so long as all your lamps match the input voltage used.

As you can see looking at your current switch it was never meant to be disassembled/opened up. Attempts to open them up do not always go well.
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php
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reddog
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Joined: Aug 31, 2006
Posts: 52
Location: Port Coquitlam BC Canada

PostPosted: Tue Sep 18, 2018 6:56 pm    Post subject: Reply with quote

check the high beam switch
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Bruce (reddog)
1952 M38 CDN
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wesk
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Location: Wisconsin

PostPosted: Tue Sep 18, 2018 8:28 pm    Post subject: Reply with quote

Another good point however checking the switch requires some knowledge of VOM useage and wiring, all of which we are still working on here.
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php
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