LMTV ECU Voltage Regulator location?

[Ronmar]

you can leave ground connected to the truck, but disconnect AND INSULATE the terminals on the 14, 28 and E terminal cables.

Connect one jumper cable lead from alt gnd terminal to - on your 24v test battery
connect a second jumper cable lead from the 14V alt terminal to the middle of your 24V battery(where the two batts are tied together).
connect a 3rd lead between the 28V alt terminal and the +24 terminal on your 24v battery.

once running and all the cables are good, use a small jumper from the alt 28v terminal to the E terminal on the regulator to bring the alt online then you can start measuring voltages...

 

[Chrispy23]

Having the same code as you! Just purchased a 99 m1079. When thrown into drive the truck bogs down / doesn’t want to accelerate. Will stay at about 5-10 mph until I’m about 50-60% pressed on the throttle for about 10-20 seconds. After that initial shift it drives perfect and shifts great, until comes to a stop and does it again. Curious if you are having any drivability issues in first gear from a stop.

Hey all, I've got a new to me 2001 m1078a1 that started throwing the D1323 code, voltage from ECU high, on the Trans.

So im trying to locate the ECU voltage regulator, part # 19207-12378784-001

Ive read as much as I could f on here and tried to dig into the service manual but I just cant seem to figure out where this part is located in/on the truck.

Any help greatly appreciated as I am scrambling to try and have this up and running for our towns 4th of July parade!

 

[Ronmar]

nevermind

 

[Chrispy23]

nevermind

it may be in not 100% the correct forum, but the same trans code made me curious if they are also experiencing the same issues as I am with the code. Or if other have experienced with this issue!

 

[Ronmar]

electrically controlled/electronic transmission, so the power system must be correct for proper operation.

clean all the connections between batts and power panel.
The grounds are trash on al these vehicles. Clean all the grounds... starter to drivers frame, alt to frame, cab to frame behind grill on passenger side, power panel to dash and dash to cab. Strip them to bare metal, throw the star washer in the trash, re-assemble with coppercote or dilectric silicone grease, then re-assemble. apply spray paint or galvcote over top of the assembled connection.

What batts are you running. the four 6t batts are too big for the 60/40 alt and regularly cause issues if they are not capable of being charged, or are not mostly charged(heavy alternator load).

then there are the alternator running voltages. should be 14.1/28.1... What are yours?

 

[Chrispy23]

electrically controlled/electronic transmission, so the power system must be correct for proper operation.

clean all the connections between batts and power panel.
The grounds are trash on al these vehicles. Clean all the grounds... starter to drivers frame, alt to frame, cab to frame behind grill on passenger side, power panel to dash and dash to cab. Strip them to bare metal, throw the star washer in the trash, re-assemble with coppercote or dilectric silicone grease, then re-assemble. apply spray paint or galvcote over top of the assembled connection.

What batts are you running. the four 6t batts are too big for the 60/40 alt and regularly cause issues if they are not capable of being charged, or are not mostly charged(heavy alternator load).

then there are the alternator running voltages. should be 14.1/28.1... What are yours?

cleaning all of the grounds is next on my to do list. The original batteries were shot, so I went with a brand new set of group 24 batteries. Only having driven it a few times, videos of it driving prior to me owning it it shifted great, and then once the new batteries were swapped in following the same wiring diagram the issue of struggling to shift out of first begin. As for if the transmission code existed prior, I am unsure as it was not checked

 

[Dexis]

That is different than my original issue. Mine really started acting up under higher speeds and engine load. First happened at highway speed and afterwards at 40+ for the most part. During that time it would operate fine at lower speeds, offroad on the property, 0-15mph-ish.

I still haven’t sorted this out but if i had to guess it sounds like we likely have a different set of issues manifesting that specific code.

 

[MatthewWBailey]

cleaning all of the grounds is next on my to do list. The original batteries were shot, so I went with a brand new set of group 24 batteries. Only having driven it a few times, videos of it driving prior to me owning it it shifted great, and then once the new batteries were swapped in following the same wiring diagram the issue of struggling to shift out of first begin. As for if the transmission code existed prior, I am unsure as it was not checked

A good way to do grounds..,

A0 Alternator excite wire question- Get Well grounded

now that it is warm... my alternator occasional works LOL. (200 amp Hummer) Will the excite wire get voltage if the alternator ground is not at all or is poorly connected? Knowing that will help me diagnose if it is that or ground (or regulator)

www.steelsoldiers.com

I had shifting issues on my A1 continuously until redoing ALL of the 3 ground straps and terminations plus adding a fourth&fifth to the cab. Haven't seen a code since. All are retapped into the steel frame and into the AL can frame with that CARC paint ground off. The existing cab ground strap is hard to get to on the frame so I left it and added 2 on either side

 

[Chrispy23]

A good way to do grounds..,

A0 Alternator excite wire question- Get Well grounded

now that it is warm... my alternator occasional works LOL. (200 amp Hummer) Will the excite wire get voltage if the alternator ground is not at all or is poorly connected? Knowing that will help me diagnose if it is that or ground (or regulator)

www.steelsoldiers.com

I had shifting issues on my A1 continuously until redoing ALL of the 3 ground straps and terminations plus adding a fourth&fifth to the cab. Haven't seen a code since. All are retapped into the steel frame and into the AL can frame with that CARC paint ground off. The existing cab ground strap is hard to get to on the frame so I left it and added 2 on either side

Very good to know, it’s funny how something so simple as a ground can cause issues like this. The truck was sitting for 3 years, and then was shipped 2500 miles to me, I can see potentially humidity, something jostling around, etc. causing grounding issues.
By any chance do you have a schematic for the 3 grounding locations? I’ll be able to take a look and trace them, but am not near the rig for about a week.
Thanks for the advice!

 

[MatthewWBailey]

Very good to know, it’s funny how something so simple as a ground can cause issues like this. The truck was sitting for 3 years, and then was shipped 2500 miles to me, I can see potentially humidity, something jostling around, etc. causing grounding issues.
By any chance do you have a schematic for the 3 grounding locations? I’ll be able to take a look and trace them, but am not near the rig for about a week.
Thanks for the advice!

The parts TM shows the locations of all 3. (Top of forum page)
Repair parts and special tools list
TM 9-2320-365-24P

 

[Chrispy23]

The parts TM shows the locations of all 3. (Top of forum page)
Repair parts and special tools list
TM 9-2320-365-24PView attachment 951071

Was reading over the TM as we speak. Will check back in next week and hopes this at least helps the situation a bit. If not, it’ll be good preventative measures.

 

[MatthewWBailey]

I can see potentially humidity, something jostling around, etc. causing grounding issues.

The method of installing these cables by S&S was sketchy. They CARC'd the whole frame and body first, THEN tried to attach ground cables to those surfaces using star washers (lock washers) as a means of cutting thru the paint, which is not reliable at 24v but commonly used on AC systems (120v & up). So even a little corrosion between the lock washer and the frame interrupts the continuity.

 

[MatthewWBailey]

Was reading over the TM as we speak. Will check back in next week and hopes this at least helps the situation a bit. If not, it’ll be good preventative measures.

There are some cab electrical issues that also occur bc of the poor negative lead connection (ground). It's a real pain. Grinding off the CARC where those braided cables attach fixes the issue.

 

[Chrispy23]

The method of installing these cables by S&S was sketchy. They CARC'd the whole frame and body first, THEN tried to attach ground cables to those surfaces using star washers (lock washers) as a means of cutting thru the paint, which is not reliable at 24v but commonly used on AC systems (120v & up). So even a little corrosion between the lock washer and the frame interrupts the continuity.

AsI was looking the other day, I was very confused on the star washer attached to the cab ground. Guess the military didn’t care about electrical functionality… lol

i have also discovered, that although new batteries were just installed there is a large amount of corrosion built up on the terminals (assuming from the old 6tl batteries.)

In the process of making all new battery cables, and adding an additional ground from them as well.

 

[Dexis]

AsI was looking the other day, I was very confused on the star washer attached to the cab ground. Guess the military didn’t care about electrical functionality… lol

i have also discovered, that although new batteries were just installed there is a large amount of corrosion built up on the terminals (assuming from the old 6tl batteries.)

In the process of making all new battery cables, and adding an additional ground from them as well.

Can an additional ground strap be run straight from the battery’s themselves straight to the frame rail without any issues or weird surprises. Tried to add an extra ground to a riding mower years ago and had an oopsie so just want to make sure I wouldn't be doing anything stupid.

 

[Ronmar]

Not sketchy, neglighent…

Can an additional ground strap be run straight from the battery’s themselves straight to the frame rail without any issues or weird surprises. Tried to add an extra ground to a riding mower years ago and had an oopsie so just want to make sure I wouldn't be doing anything stupid.

The possible issue when doing this is that if something happens to the main ground lead between batteries and starter the starter will attempt to pull all its starter current thru the alternate ground path and the starter to frame ground, and the braided straps are not rated for high current... I see no advantage to doing this... Just clean and inspect the normal grounds and the battery to starter cables and it will work just fine...

 

[Dexis]

Not sketchy, neglighent…

The possible issue when doing this is that if something happens to the main ground lead between batteries and starter the starter will attempt to pull all its starter current thru the alternate ground path and the starter to frame ground, and the braided straps are not rated for high current... I see no advantage to doing this... Just clean and inspect the normal grounds and the battery to starter cables and it will work just fine...

Well for the record i was going to use a section of 4/0 welding cable I had pulled off a solar battery bank when I upgraded the system, so it would be alot beefier than the braided cable, if that makes a difference.

 

[Ronmar]

But to what purpose? You still need the heavy cable to starter motor case, and it still must function properly, so the added cable battery to chassis serves what purpose, When there is already one battery to starter and a properly cleaned main ground connection strap starter motor to drivers frame/chassis?

well that was a weird quotation… that first sentence was something I typed last week in response to someone else about the S&S ground quality and never posted… the forum must have held it in a buffer and added it to todays posting

 

[Chrispy23]

Not sketchy, neglighent…

The possible issue when doing this is that if something happens to the main ground lead between batteries and starter the starter will attempt to pull all its starter current thru the alternate ground path and the starter to frame ground, and the braided straps are not rated for high current... I see no advantage to doing this... Just clean and inspect the normal grounds and the battery to starter cables and it will work just fine...

I will be starting by doing all existing ground cleanings before doing anything else. If not to solve my issues, it’ll be a good bit of preventative maintenance