low voltage at amp meter

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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mtcowboy
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low voltage at amp meter

Post by mtcowboy » Tue May 05, 2015 5:47 pm

After looking at the wiring for the temp gauge and saw that it's missing a wire from the spider wiring, the amp gauge only registers in the yellow. Checking voltage I have 19.7 volts. I know I need to get a new spider wire but what is uo with the low voltage? I'm betting that I need to rebuild the generator? Thanks
53 m38a1 original 23,000 miles a daily driver


mtcowboy
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Re: low voltage at amp meter

Post by mtcowboy » Wed May 06, 2015 5:54 pm

Update, I had a loose wire and got it chargeing. I found out that I have a M170 battery gauge with the 4 wire spider harness. This leaves the temp gauge with out the proper wire. I found a 5 wire harness but it SAYS IT IS USED FOR M series vehicles with rubber shell connectors on the gauges. Would that fit with the douglas connectors?
53 m38a1 original 23,000 miles a daily driver

skyjeep50
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Re: low voltage at amp meter

Post by skyjeep50 » Thu May 07, 2015 4:52 am

First, go over to the Willys M Jeeps web site and look through the "Downloads" section for all the technical resources and manuals dealing with your jeep. See: http://www.willysmjeeps.com/v2/modules. ... oad&cid=57
http://www.willysmjeeps.com/v2/modules. ... ght=parker
Then you will have a better understanding of how it all fits together. You can use a voltage meter with your jeep instead of the old amp gauge and you can convert a five wire spider harness but you'll have to match the ends to the gauge's connectors - Parker to Parker or Douglas to Douglas. Its pretty easy - you can buy the parts and solder and crimp the correct ends on the harness. On my M38 I converted to all late M-series Parker-equipped gauges mainly because they seemed to be more plentiful and cheaper in the spare parts arena. But there are repro Douglas gauges as well.

Joe Gopan
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Re: low voltage at amp meter

Post by Joe Gopan » Thu May 07, 2015 5:14 am

The Instrument panel 4 and 5 wire Spider Harnesses with Packard (Rubber)and Douglas (Metal) connectors are available thru many of the MV parts dealers who advertise in Army Motors.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Joe Gopan
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Re: low voltage at amp meter

Post by Joe Gopan » Thu May 07, 2015 7:45 am

Appears that you have the Bat/Gen Indicator,Bat/Gen Indicator has a Red, Yellow, Green scale. Was that voltage with the engine revving or a reading across the batteries with the engine off? If you determine the regulator is at fault, don't waste time monkeying with it, install a new GI Surplus 25 AMP Solid State Regulator. They stay in perfect adjustment until they die.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO


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