quick headlight question for the FMTV/LMTV

hummer4x4guy · May 2, 2014

Are the headlights on these trucks 12 or 24 volt?
A guy is selling the LED headlights which are 12 volt and lists them for military trucks like these and the humvee and I know the humvee uses 24v headlights and I was trying to tell him most military trucks are 24v with regards to headlights..
Am I wrong?

ke5eua · May 2, 2014

FMTV Headlight Lamp
Need a replacement headlight lamp for your 2 1/2-ton or 5-ton FMTV? Use NSN 6240-01-420-8320 to get the 12-volt lamp with pigtail connectors. The NSN for Item 12 in Fig 57 of TM 9-2320-365-24P and TM 9-2320-366-24P is wrong.

Source:

http://psmag.radionerds.com/images/3/3e/PS_Magazine_Issue_558_May_1999.pdf

The LMTV TM's here show the correct NSN.

This link will give you the FedLog data with cross reference to other applications.

http://www.parttarget.com/6240-01-420-8320_6240014208320_2HE692.html

psmag.radionerds.com_images_3_3e_PS_Magazine_Issue_558_May_1999.jpg

Rodney Lough Jr · May 5, 2014

Maybe this will help.

Screen shot 2014-05-05 at 2.39.53 PM.jpg

OktobrVega · Aug 13, 2015

No headlight voltage on new M1078

No voltage for headlights. Guess gonna check K7 K8 relays but they appear to be new. (high / low beam) relays.

Any ideas where else I can check?

Suprman · Aug 13, 2015

Make sure the correct relays are in there. There is a combination of 12v and 24v relays used they all look the same. Some relays require the center connection some dont. I only buy replacement relays with the center connection though. The panel cover has a diagram you have to read it carefully. Verify with a multimeter 12 and 24 volt at the left side of the panel there are round terminals. Look under the truck make sure the lights are connected. Someone may have done a quick swap if it had leds before drmo. After that I would swap the light switch.

OktobrVega · Aug 13, 2015

ok Will will run through your suggestions. Thank you bud

Lmtv772 · Aug 13, 2015

I definitely would check the light switch. If it's the push button switch I'd double check it.
I have a switch if you need one.

OktobrVega · Aug 13, 2015

Wound up being K7 & K8 relay. Light switch was my next try. Thank you gentlement for the help. Modified Sylvania H6024's with H4 plug soldier spliced heat shrinked to military connectors. Works like a champ now.

Ukraine Train · Aug 13, 2015

OktobrVega said:
Modified Sylvania H6024's with H4 plug soldier spliced heat shrinked to military connectors. Works like a champ now.

Good to know! So headlights are 12v then? In general, what circuits are 12v and which are 24v?

Overdrive · Sep 20, 2015

OktobrVega said:
Wound up being K7 & K8 relay. Light switch was my next try. Thank you gentlement for the help. Modified Sylvania H6024's with H4 plug soldier spliced heat shrinked to military connectors. Works like a champ now.

Do you have a part number, civilian, for the K7 & K8 relays?
Thanks!

Suprman · Sep 20, 2015

The power panel has 2 buss bars going across feeding the breakers. One feeds 12 and one 24. At the left side of the panel are round lug holes that correspond. The relays are mapped out on the back of the panel cover. It's confusing some of the 12v relays switch 24v circuits and vice versa.

Overdrive · Sep 20, 2015

Tracking down relay part numbers.
Looking at an old thread with PDF of power distribution panel it looks like the 12v relays are standard Bosch style SPST 4 pin and SPDT 5 pin... is that correct?

Suprman · Sep 20, 2015

The 2 relays are standard bosch style spdt relays in 12 and 24 volt. They
can be found inexpensively on the internet in bulk. Only get the 5 pin versions so they will
work in all positions. The military should have done this to begin with. The 4 pin version only adds to
confusion when mistakenly used in the wrong position. Make
yourself one of these jumper wires. You can take a relay out and use it to bypass and turn on whatever you need to if you have problems. I have used it before. Good to have for troubleshooting also.

Overdrive · Sep 20, 2015

Ok excellent. So jumper wire for emergency bypass on a bad relay and get a bulk pack of just the 5 point SPDT relays and have both 12v and 24v versions.
Thanks Superman. Building an emergency repair and recovery LMTV kit in preparation of actually winning one at auction.

Wish there was a consolidated pinned post for part numbers. Fan belts for water pump and generator are next but I snagged those numbers from another post.

kenet3621 · Nov 17, 2015

I recently bought a 1994 LMTV and replaced both headlights so I could use H4 bulbs. The wiring is 12 volt for the headlights.

FloridaAKM · Jul 8, 2016

LMTV Head Lights Voltage

We have been thru this before with other LMTV owners, but I had to replace @ least one headlamp since it was cracked in half when I received it. Listening to the current owners told me that voltage of the lamps was 12vdc instead of 24vdc like regular trucks, so I ordered bulbs & replacement lenses from a favorite vendor for 12 vdc. The first bulb removed was destroyed, so no info from it; the second unit was intact & had a manufacture date of 6/2013 & was 24VDC marked. I think my truck has started to become a parts truck @ some time & stuff was removed & replaced with what ever was @ hand. Anyway, after measuring the voltage @ the buckets, it was 12.5vdc as it should have been. New lenses & replaceable bulbs have been installed & work great. Thanks again to the SS members who post info which helps to advance the utilization of these surplus trucks!

The heater-A/C unit is a story for another thread next week! ;-)

tterbo · Jul 8, 2016

OktobrVega said:
No voltage for headlights. Guess gonna check K7 K8 relays but they appear to be new. (high / low beam) relays.

Any ideas where else I can check?

For whatever reason my headlights randomly decide to not work every once in a while. When this happens I just switch out the high beam relay and low beam relay and everything works again. Then it will happen again so I switch them back and it works everytime. Weird problem for sure. Just going to put two new relays in both and see if the problem stops...Anyway, definitely check the relays first.

tterbo · Jul 8, 2016

FloridaAKM said:
We have been thru this before with other LMTV owners, but I had to replace @ least one headlamp since it was cracked in half when I received it. Listening to the current owners told me that voltage of the lamps was 12vdc instead of 24vdc like regular trucks, so I ordered bulbs & replacement lenses from a favorite vendor for 12 vdc. The first bulb removed was destroyed, so no info from it; the second unit was intact & had a manufacture date of 6/2013 & was 24VDC marked. I think my truck has started to become a parts truck @ some time & stuff was removed & replaced with what ever was @ hand. Anyway, after measuring the voltage @ the buckets, it was 12.5vdc as it should have been. New lenses & replaceable bulbs have been installed & work great. Thanks again to the SS members who post info which helps to advance the utilization of these surplus trucks!

The heater-A/C unit is a story for another thread next week!

Please update us on your A/C install. I almost have everything to do mine. It is just too hot down here to not have it.

FloridaAKM · Jul 8, 2016

My A/C install consists only of replacing the center console with a new A/C-heater unit from surplus since mine is loose from the firewall & non functional. The army mechanics were looking for gold coins in the dash; upon not finding any, they trashed the dash sheet metal & left it that way. After getting a title & other paperwork for the DMV to make this gal legal, the rest of the A/C will happen! Look @ the other guys writeup on A/C installation for how to do it right!

quick headlight question for the FMTV/LMTV

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