Engine stops running when turn lights on!!!

Create a thread to track the progress of you MB/GPW restoration progress. Previously a General Discussion board.
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Elmhousewillys
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Engine stops running when turn lights on!!!

Post by Elmhousewillys » Sun Sep 01, 2019 4:45 am

Hi to everyone who reads this....
Am new to this forum and recently the proud owner purchase of a 1945 Willy's mb, along time dream except I have an electrical gremlin!!
With the engine running and turn on the lights, she stops!!! It's a 6volt system, the battery shows 6.2volts on a meter. My thoughts are a dodgy light switch or possibly voltage regulator??
Would love to hear some views if anyone has experienced similar fault!!


Wolfman
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Re: Engine stops running when turn lights on!!!

Post by Wolfman » Mon Sep 02, 2019 4:34 am

When you turn the lights on, does everything go dead ???
Including the lights ???
Going to take the battery and starting system off the list. It started and ran. Until you turned the lights on.
At fast idle, you should be getting a reading of around 7.4 volts at the battery, but even if the generator was not charging, the battery is strong enough to start the engine, so just turning on the lights should not pull the battery down enough to kill the engine.
My guess is a weak connection between the starter switch and amp. gauge. Or the amp gauge itself. After the amp gauge, the light and ign. circuits split and go different directions.
With the lights on, I would start down the circuit with a volt meter or test light and see where it goes dead.
Might also look for a connection that was getting hot.
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Elmhousewillys
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Re: Engine stops running when turn lights on!!!

Post by Elmhousewillys » Mon Sep 02, 2019 9:25 am

Thankyou for your ideas, just to add, when I tried restarting, she turned over, didn't fire, then starter went dead. On checking under hood, starter motor was smoking and battery leads hot, so disconnected.
I currently have starter motor being checked over, when I have it back, will start checking voltage when running!!
Advice appreciated
Regards Martin

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Re: Engine stops running when turn lights on!!!

Post by artificer » Mon Sep 02, 2019 9:36 am

When you get the starter back run through this checklist:
http://jeepdraw.com/images/Starter-Diag ... 8.3.15.pdf
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

Elmhousewillys
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Re: Engine stops running when turn lights on!!!

Post by Elmhousewillys » Tue Sep 03, 2019 3:39 am

Thanku very much for the check list info and your time to reply.....
Regards 😀

Elmhousewillys
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Re: Engine stops running when turn lights on!!!

Post by Elmhousewillys » Thu Nov 07, 2019 7:45 am

Hi all who read this.....

Bit of an overdue update on my fault finding issue regards this topic. The problem was the starter motor!!!
Had it rebuilt as brushes and internal ignition contacts were faulty and earthing out. After bolting starter back on and running, I checked all voltage outputs at the dynamo/regulator and she's showing good readings all round even with the lights on!!!!
So the 6v system all working great.....and driving around abit more relaxed😀
Thanks again to those who replied with their thoughts....
Martin


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