12v 24v dilema

[85-m1028]

not realy sure where this goes but thought I'd try here.. I have a 98 military hmmwv turbo 6.5 drive train I'm assuming I need to run this with 24 volts,
starter
engine computer

Do the civy HMMWV's use 24v?

I'm putting this in a 75 gmc Jimmy and need 12v for the rest of the vehicle.
what would be the best way to go about this??

[Hammered Scout]

12 volt

[BigKofJustice]

Just to clarify,

Civilian/Commercial Hummers [H1] are 12 volt electrical system.

HMMWV/Military are 24 volt. I know a lot of people call them either a humvee or a hummer. I call my truck a humvee only because these days, people hear the word hummer and they think of an H2.

If it has a mechanical injection pump with a mechanical wastegate for the turbocharger, then its a military setup, so it will be 24 volt.

If it has computer controlled injection pump, "drive by wire" throttle, its a civy drive train which is 12 volt.

[ycis]

easiest way to verify is to look at the batteries and see how they are wired.

pos to pos and neg to neg = 12v setup.

[stjames151]

I went through this before when I converted. The HMMWV is 24v...always. Almost all Mil-Spec land vehicles are. Three ways to deal with it, 1) put a mechanical fuel pump and civi starter and alternator on the new engine, 2) set up dual systems and put a 12-24 converter to charge one of the systems (you can get em at photo-voltaic "solar" shops), 3) convert the truck to 24v(Mostly lights, but can be full re-wire depending on what you want to run). 2 will work fast and easy, but not for long. 3 is a pain in the ass.

[actionpaintball]

Your tranmission (4L80e) is already 12 volts. The HMMWV A2 has a dual output alternator that charges both 12 and 24 volt circuits. Your transmission taps off one battery and sends 12 volts to a bi-voltage relay next to the brake switch. When keyed on-the 24 volt relay then powers all 12 volt circuits. The transmission computer is fed through the two vehicle speed sensors (VSS) that are mounted on the transmission case, and sees input from these two sensors, a 12 volt powered brake switch, and throttle position sensor. The 6.5 turbo is 100% mechanical and the only 24 volt solenoid is the on/off switch for the injector pump.

Crib Notes: If you are adapting the drivetrain-you can simply go to a 12 volt system by just changing the solenoid in the injector pump-everything else is already 12 volts.

I have the same set=up in my personal HMMWV ('92 with '98 drivetrain)

[85-m1028]

Originally Posted by BigKofJustice

Just to clarify,

Civilian/Commercial Hummers [H1] are 12 volt electrical system.

HMMWV/Military are 24 volt. I know a lot of people call them either a humvee or a hummer. I call my truck a humvee only because these days, people hear the word hummer and they think of an H2.

If it has a mechanical injection pump with a mechanical wastegate for the turbocharger, then its a military setup, so it will be 24 volt.

If it has computer controlled injection pump, "drive by wire" throttle, its a civy drive train which is 12 volt.

It's a drive by wire, so must be a civy

control box


engine


this is what threw me off


all the plugs found a home except for this plug has loose wires at the end that plugged into a dash panel, but the gauges are gone so I don't know whats for what??

[85-m1028]

Originally Posted by actionpaintball

Your tranmission (4L80e) is already 12 volts. The HMMWV A2 has a dual output alternator that charges both 12 and 24 volt circuits. Your transmission taps off one battery and sends 12 volts to a bi-voltage relay next to the brake switch. When keyed on-the 24 volt relay then powers all 12 volt circuits. The transmission computer is fed through the two vehicle speed sensors (VSS) that are mounted on the transmission case, and sees input from these two sensors, a 12 volt powered brake switch, and throttle position sensor. The 6.5 turbo is 100% mechanical and the only 24 volt solenoid is the on/off switch for the injector pump.

Crib Notes: If you are adapting the drivetrain-you can simply go to a 12 volt system by just changing the solenoid in the injector pump-everything else is already 12 volts.

I have the same set=up in my personal HMMWV ('92 with '98 drivetrain)

Do I need a brake switch?

I notice there's no torque converter lock up, do these not come with that option?


t-case and wiring

[85-m1028]

a few more

Some power supply wires, these go into the control box


alt


top


other side


shifters


guage panel, notice the custom exhaust, need to get a factory down manifold

[Guinness44]

Those shifters are definitely not civy. (Neither the gauge panel).

[85-m1028]

the lot came from a company that builds concept vehicles. its been sitting on a pallet about 9yrs. I was told it has about 5000 miles on it.

[stjames151]

1st:Not sure thats commercially available from "hummer" but its definitely not HMMWV (MilSpec) either. The MilSpec stuff utilizes as few computer/harness stuff as possible because of EMP (and other) possibilities in battle zones (I'm told). My truck had the NA engine, but only about 30ft. of wire in the engine compartment (mostly 00gauge from bat.). The A2's have a little more, but I've never seen that much cable under the hood of a HMMWV. The A1, A2, Civvy all have the same body and base structure. It'd be pretty easy to make a Civvy look like a HMMWV. To be sure, look on the top of the left side frame rail near the front of the trans. If you see a 4-6 digit TIG'd in number, its probably MilSpec. If its a plate or alpha-numeric it's probably Civvy.
2nd: I'm pretty sure the HMMWV came with a 4L80 trans (new) and 4L60 (old), not 4L80E (electronic). I dont think either comes with an electronic lock-up TC but both are retrofit capable.
3rd:The harness connections look MilSpec, but that could be for water proofing. As I said, I'm not that familiar with Civvy.

[BigKofJustice]

That doesn't look like a civilian control box housing, at least for the pre ABS trucks. I'll take a picture of mine and post it, I'm taking out my interior for cleaning, repair, and on the 92's to 98's I believe the control box/computer sits on the dog house/engine conver. At a certain year [99?] they moved the computer under the hood near the abs system near the wash tank.

That's for civy trucks though.

[85-m1028]

I've been digging through the chiltons electrical diagrams for anything that will tell me what the six wire plug goes to. so far I've got check engine light, ignition hot, oil pressure and ??

I'm finding lots of custom stuff on this thing.

just bolted on a 12v starter..

[stjames151]

send me a pic of the computer and S/N and I think I can check it against some of the records I've found while researching mine. The only thing with a MilSpec connector is the computer. The rest of it will not pass their immersion tests. Further, the computer is in a retro'd box. It looks to me like someone re-fit a civy in a HMMWV chassi. can you find an OBD1/2 interface anywhere on the harness? Hook up to it if so and it will give you TONS of info about the original vehicle. HMMWV's dont have this interface anywhere as far as I know. They check the components individually. Xhumvee.net was doing this kind of conversion for a while, quite succesfully in fact. They did lots of different conversions untill they ran out of stock. If you can pull a history report, a previous owner may be able to give you more info (or lead you in the right direction). It'd be worth the $19 if you can find anything out. It should show the VIN/SN report from the referee that ok'd it if you're in a state thats as "big brother" as CA.

[BigKofJustice]

Originally Posted by stjames151

ok'd it if you're in a state thats as "big brother" as CA.

Funny thing about California and diesels is that they don't test them.

[stjames151]

Thats true, but if you swap the engine, DMV mandates that you contact a refferee to notify them of the new #'s. If the swap was done before it was registered in CA, then the #'s would have been recorded by a refferee/officer (usually CHP) at the time of VIN verification. Both would be discoverable events. I'm not suggesting that you look for SMOG records.

[85-m1028]

I took an ohm meter and traced the wires from the plug back to the pin at the cpu. but the chiltons electrical diagram doesn't specify pin designation according to the plug that goes into the pcu.

there is no plug for the obd 2, but there is a small plug on the side of the box with 3 wires red, black, blue

[stjames151]

I do recognize the yellow tags on the individual wires as having MilSpec labels, but have not seen similar harnesses in manuals or .MIL trucks to date. However, there are lots of pages I haven't seen because they don't pertain to my truck. Further, the intermediate harnesses are not .MIL as far as I have ever seen in any MilSpec vehicle. I do have a set of digital manuals that are more recent than the most recent release of HMMWV's to the public. Are the 6 wires you're trying to place all marked precursor "q"? What are the other marking on the wires?
I'd love to see your truck and am in SoCal regularly, so if you want a copy, PM me. S/N on the chassi may produce more results, but dont post that in public.

[85-m1028]

the plug wire ends are designated with a precurser ( J1) and below it is a letter ( blue wire "J", gray "L", yellow "H", purple "K", another blue "S", black "R")

so I've got a hybrid of .mil spec and civy, makes sense to me.

I found a website of the guys I got this stuff from, I've called a couple of times to see about getting more info, but no one answers and no one calls me back. Not sure if any one would even know over there!

http://www.millenworks.com/html/index.htm
I think it was the HTTV demo platform

I'm affraid the truck still isn't much to look at yet "stock form" but I have most of what I need to get started, just wanna get make sure this engine set up is gonna run right.
give me a call if your town 949-244-3782 Roman

[stjames151]

thats quite a truck. Looks like there were a lot of controls on the dash that ran through the computer, including axle independent adjustable ride height.