M38 electrical problem

c90001 · Post by **c90001** » Wed May 10, 2017 3:04 am

Hello everyone who is expert with the Elektirk of the m38 ?
I have installed new cables and a new generator and new regulator (26640473-03 Vap air).
The tank gaug and the pressure gauge are working but the temperature gauge(AC1512422) and the charge gauge(SW 504-G) do not work.
The cables 9 and 8 from the regulator to the battery display go to the correct connections. Cable number 9 has however always voltage even if the ignition is switched off. This can not be. The temperature display is fully off when only the ignition is switched on. I have always grounded everything, the grounding I can exclude as error.

maybe the sender are wrong? From Water temp i bought this item:
http://www.ebay.com/itm/Jeep-Willys-M38 ... 96&vxp=mtr

G740 · Post by **G740** » Wed May 10, 2017 5:11 am

Frank,
If you are using a solid state regulator, which by the name you have listed I believe it is, #8 and #9 are rendered useless. They need to be connected together and left up behind the dash. You will need a 5 wire spider harness to connect up a voltmeter instead of the ammeter. The ammeter will not function with solid state regulators because there is no shunt bypass in this type of regulator. A mechanical regulator will be required in order to make the ammeter work.
John

c90001 · Post by **c90001** » Wed May 10, 2017 5:58 am

thank you so much for your information, i will buy a old regulator and than all will be working.

4x4M38 · Post by **4x4M38** » Wed May 10, 2017 7:09 am

Hello Frank,
What is the serial number on your dash plate?
Does your temperature gauge have a resistor on the back?

That sender you bought from Brent Mullins is for the original
resistor equipped 6 volt gauge the early M38's came with.

Take care,

4x4M38 · Post by **4x4M38** » Wed May 10, 2017 7:17 am

Here is a page from Wes' photos showing the early gauges and
part numbers.

http://www.willysmjeeps.com/v2/modules. ... _album.php

c90001 · Post by **c90001** » Wed May 10, 2017 7:30 am

i bought all pices and and before nothing in the car was original. i bought also all gaugs and they have no resister. i bought all new pices for the g740 but same pices show only m38.

c90001 · Post by **c90001** » Wed May 10, 2017 7:35 am

but the themp sending was for the G740 and this modell has 24Volt

c90001 · Post by **c90001** » Wed May 10, 2017 7:42 am

so i need the resistor with 95 ohm but i think its not possible to find,

4x4M38 · Post by **4x4M38** » Wed May 10, 2017 7:48 am

Good evening Frank!

It's a bit of a minefield just buying parts that say they are for the M38.

There were many changes to parts during production as well as after
they were in service. In many cases replacement parts were a direct
replacement but had different part numbers.

Some were not, however. It is very important that you learn to read
the parts manual Ord 9 G740. It has most original numbers and
replacement parts listed by vehicle dash plate serial number.

It can be fun, but can also drive you crazy!