LMTV M1078 Tachometer

[lmtvjunky]

Hello to everyone here, it's a pleasure to meet all of you and to enjoy all the experience and knowledge of military vehicles. I have a question about installing a tachometer in the M1078, not too many trucks had them and I'd like to do an install. Without splitting the engine from the tranny, does anyone have a flywheel or a separated engine to get an accurate tooth count on the flywheel?
I purchased a couple magnetic sending units, both single and duel outputs, there's is already a magnetic sending unit in the bell housing and another spot for one more but it's being used for a vent, which can be rerouted. Any help would be greatly appreciated. Also I am going to start posting a whole lot of pics and threads regarding these trucks. I have 6 trucks now and 4 trailers, I've picked up a ton of random parts now and want to share my experience of working on these trucks. Erik

 

[NDT]

Welcome LMTVJunky. Steelsoldiers is turning into the go-to resource for FMTV troubleshooting, and your contributions are welcomed! Try to post lots of pics and civi-equivalent part numbers. Dig around in the "P" suffix TM's, you will be able to determine if the winch trucks had a different flywheel (I don't think so) and where the magnetic pickup is.

 

[Suprman]

Probably piggybacks off the trans harness somehow. The manual dosnt show a different harness for winch trucks so there is a good possibility the connection you desire is tucked away somewhere in the dash or behind the heater. Pic below is what the connector should look like. A tach signal should also be included in the big round ste ice diag plug to the left and down from the steering wheel. The manual shows diagnostics determining engine rpm from there. The A1 winch trucks do not appear to all have tach's. Maybe since the engine is electronic control the system auto-sets the rpm for winch operation.

Instruments. The Instrument Panel includes all gages that provide the operator with information about vehicle
condition and operating status. The speedometer (1, Figure 1-13) receives electrical input from the WTEC II Vehicle
Interface Module (VIM) on vehicles equipped with WTEC II transmission controls. The speedometer receives electrical
input from the WTEC III transmission ECU on vehicles equipped with WTEC III transmission controls. The WTEC II
VIM and the WTEC III transmission ECU are both located behind the kick panel. Tachometer (2) input is provided by
the engine speed sensor located on the engine flywheel housing. The fuel gage (3), oil pressure gage (4), water
temperature gage (5), front brake air pressure gage (6), rear brake air pressure gage (7), and VOLTS gage ( receive
electrical signals from sending units. The sending units respond to changes in fluid level, pressure, temperature, and
DC current and send this information to the gages.
1-18

 

[Suprman]

 

[Johno176]

Do you happen to know if the A0 and A1 tachometers are the same?

 

[Suprman]

The A1 winch truck that I have did not have a tach. I believe this is due to electronic engine rpm control. Less operator options.

 

[Johno176]

Suprman: I'm going to install a hydraulic package (pto/pump, tank and winch) on a non outfitted A1. Am I correct in assuming the wiring harnesses are all pre-wired for this option? If so, then by hooking in all the components does this complete the circuit to let the ECM know to adjust engine rpms. Thanks, John

 

[Suprman]

I dont have much A1 experience my A1 truck has collision damage. I believe there is a trigger lead that kicks up the rpms with winch engagement after the pto is engaged. Matt in MI has a complete winch setup he listed for sale it is a first gen though. The A1 manuals are interactive on the diag computer. I can prob ask someone to run thru the winch problem flow chart it should tell which wire to check.

 

[Lmtv772]

My LMTV (with winch) doesn't kick up the RPM , you have to raise it via the hand throttle.

 

[Suprman]

Is your winch truck a first gen or A1.

 

[Lmtv772]

Is your winch truck a first gen or A1.

as first gen as you can get, it's the second prototype from 1993

 

[Suprman]

The A1 is computer controlled throttle no hand throttle to rpm up when winching.

 

[lmtvjunky]

Ohhh superman, do you have any of those tachometer s you showed in the pics?

 

[Suprman]

No sorry I am going to use that one. It's a Medallion tach they make civ ones that are almost identical. The Internet is full of them.

 

[lmtvjunky]

Darn, you have such a glorious invintory of parts I thought you might be holding on to a few. I'm sending you a parts wish list now, emailed!

 

[Keith Knight]

To answer your original question I have a 2004 transmission waiting to go in my 2003 LMTV and the tooth count is 134. I'll try attaching a photo.....I tried with out success.

 

[Suprman]

I am in the process of pulling a trans right now. It's larger and heavier than I originally thought. Unless you are lifting it out the top I am thinking a very large transmission lift would be in order. I measured the trans I am thinking either the truck has to come up a few inches or the trans has to come down then shift sideways slightly to clear out from under the truck.

 

[Keith Knight]

If I could figure out how to post pictures "MacBook" I would show you the cart I made to lower the trans onto then roll it out on the passenger side after also removing the muffler. I built it as low to the ground as possible to clear the frame. Lmtv722 and I removed the one I have and we dropped it down then slide it out. Also in one of the tech manuals near the end shows how to make a lift bracket that bolts to the transmission that you can lift it from a single point and is properly balanced.

 

[Overdrive]

Hmmm.... I was researching how to add a tach to a CAT 3116 and the info I was finding talked about an alternator driven signal for the tach and not dealing with adding anything to the trans... It sounded like this is a standard thing for diesels.

 

[Lmtv772]

That's how I did it. hooked a couples of slings to the the transmission and our front loader. removed the transmission bolts and lowered it down on a pallet. It was a bit easier , since the engine was out already.
but be prepared, It's a big hunk and is pretty heavy.