WTK Battery Gauge type and wiring

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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dlevy
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WTK Battery Gauge type and wiring

Post by dlevy » Wed Feb 28, 2018 8:47 pm

Hi Guys,

I replaced my battery gauge in my instrument panel, but not sure if it is wired correctly.

The gauge has only 1 place for a wire, but the wiring schematic reflects it should have 2 wires #8 & #9.

Even the picture in the manual shows it should have 2 wires.

(Bottom right gauge in the first picture, Top left gauge in the second))

Can this gauge be wired to work correctly?

Any thoughts?

Thanks,
Dave
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g.keating
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Re: WTK Battery Gauge type and wiring

Post by g.keating » Wed Feb 28, 2018 9:35 pm

you have a voltmeter installed instead of an amp meter. The amp meter used the 8 and 9 wires. To use your new volt meter the easiest way in to just tape off the 8 and 9 wires so that they don't short out and don't use them at all, and get a 5 wire spider wire assembly or make one wire on your spider a one into two connection, and connect it to your volt meter. The volt meter only needs one hot wire connection when the ignition is switched on.

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Re: WTK Battery Gauge type and wiring

Post by Joe Gopan » Thu Mar 01, 2018 4:18 am

The spider wires are tagged #27 and are the live feed to the other gauges. A 5 Wire Spider will solve your problem. While you're at it, a 60# Oil Pressure Gauge and Sender will give you a more accurate reading.
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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
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dlevy
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Re: WTK Battery Gauge type and wiring

Post by dlevy » Thu Mar 01, 2018 8:17 am

OK. makes sense.

Anyone know when the M38A1 was changed from the ammeter to the volt meter?

In the TM 9-8014 April 55 manual, page 217. The M38A1 has the amperes gauge and the M170 cluster on the same page got the volt meter.

Also when was the 120psi oil pressure gauge changed to the 60psi gauge?

Dave

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Re: WTK Battery Gauge type and wiring

Post by Joe Gopan » Thu Mar 01, 2018 10:24 am

They started introducing the 60# Oil Pressure Gauge sometime after mid 1955 in the M-Series trucks. The 120# Gauge was not reliable and the mechanics and operators were told "as long as the gauge moved, it was OK." M-38 and M-38A1 Jeeps would get the 60# upgrade MWO during routine visits to their support units or during engine change. Some M-38/M-38A1's never did get the 60# upgrade. Note:
The upgrade requires as matching 60PSI rated sending unit. It is getting more difficult wit time to find NOS 60# Gauges and Senders set up for the Douglas Connectors,also, some NOS 50's 80's dated 60# Gauges do not survive 60 years of storage and may not function when installed.
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
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COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

dlevy
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Re: WTK Battery Gauge type and wiring

Post by dlevy » Thu Mar 01, 2018 10:35 am

Thanks Joel. Great explanation.
Any idea on the amp vs volt gauges?

Dave

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Re: WTK Battery Gauge type and wiring

Post by Joe Gopan » Thu Mar 01, 2018 12:16 pm

The Bat/Gen indicator is a great feature as you can monitor the battery condition every time you get in to start your vehicle. That combined with the Solid State Regulator will instantly give you the condition of your system.
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

dlevy
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Re: WTK Battery Gauge type and wiring

Post by dlevy » Thu Mar 01, 2018 12:33 pm

Is there a solid state regulator retrofit kit that goes inside the original housing?

Like the ones that Kevin from Star Electric made years ago?

Dave

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Re: WTK Battery Gauge type and wiring

Post by Joe Gopan » Thu Mar 01, 2018 1:23 pm

I am not aware of any, but still being a purist of sorts, I go along with the upgrades in MWO's, Bulletins, etc., the later Solid State Voltage Regulator is trouble free and one does not spend the rest of one's life attempting to chase the adjustments of 24 Volt Voltage Regulators that are not charging according to specification. The GI Solid State Voltage Regulators stay in spec till the end and that is a long time. The Army installed upgrades for the sake of reliability. Just think, no more over/under charging or boiling batteries. :wink:
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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