Need help. M1083A1P2. Ukraine

Hello friends!
First of all, I want to say thank you to all the US people for supporting us! You have no idea how valuable it is to us!

I am writing on behalf of my relative who drives a tractor M1083A1P2.
In short, the problem is as follows:
Now the windshield is covered with ice and the windshield heating system does not work. We checked the contacts that come from the middle of the windshield, the very button that turns on this system, too. It's fine with that. But we can't find where the relay that controls this function is located.
I've looked through tons of websites and manuals on this forum, but I can't find this information anywhere, most likely because all TMs are not for armored cab versions.
Also, I can't find any pictures of this car inside, we found a fuse box and relays but I'm not sure I can post a picture of that because I'm worried it's not allowed since it's military equipment.

I would greatly appreciate it if someone could help us with this!

Welcome and greetings from the United States.
If you post any pictures, be sure any geotagging is turned off, don’t make the same mistakes as the mobiks.
Unfortunately we also do not have hard copies of the maintenance manuals for the A1P2 uparmored trucks, they are only electronic versions available to the US military. But we do know that all electrical functions of FMTVs are controlled by relays in the Power Distribution Panel (PDP) in front of the co-driver. Most likely a circuit breaker is tripped or a relay is defective or not the right type. Check under the PDP cover for a decal that might explain what each relay does.
Good luck!

NDT said:

Welcome and greetings from the United States.
If you post any pictures, be sure any geotagging is turned off, don’t make the same mistakes as the mobiks.
Unfortunately we also do not have hard copies of the maintenance manuals for the A1P2 uparmored trucks, they are only electronic versions available to the US military. But we do know that all electrical functions of FMTVs are controlled by relays in the Power Distribution Panel (PDP) in front of the co-driver. Most likely a circuit breaker is tripped or a relay is defective or not the right type. Check under the PDP cover for a decal that might explain what each relay does.
Good luck!

Click to expand...

Hey NDT,

Thank you for your answer!

Sure thing, I will not publish a photo with a geotag. Thank you for your advice. TBH I am afraid to publish any photo at all Yeah, we already found PDP but can`t recognize relay what we need, because all names are shorted and probably it could be: PTO, CTIS, etc.

Could you help with the possible name of this relay?

PTO is power take off, power for winch (if equipped), CTIS is power for central tire inflation. Look for abbreviations related to “defrost”, maybe DEF.
We are going to ask some active duty US Army contacts if they can provide insight into this circuit. This will take a day or so.

Check this module in the PDP, this circuit breaker provides power for the hot air heater and defrost. If the breaker is tripped, the button will be up. Thanks to many folks that have helped so far with this diagnosis effort.

NDT said:

Check this module in the PDP, this circuit breaker provides power for the hot air heater and defrost. If the breaker is tripped, the button will be up. Thanks to many folks that have helped so far with this diagnosis effort.

Click to expand...

We have checked this fuse and it is fine. When we press the button, it flashes green once, but does not light up and defrosting does not occur.
Most likely, the problem is precisely in the relay of this system, which may have simply stuck or burned out.
Do you have a chance to find out where the defrost function relay is located in that PDP unit?

Just sent someone a help request. Have to see if he can come up with something.

Guyfang said:

Just sent someone a help request. Have to see if he can come up with something.

Click to expand...

There are MANY on the site that have intimate knowledge of this type of truck, sadly I ain't one of them. Hopefully someone will chime in and get the right info to where it is needed!! Purdy Please?

Your in the 5 ton section, maybe move request to FMTV post since you have a FMTV…just saying, you may get more responses.

Done. I forgot to look at that when I jumped in.

Maybe its a Ground problem and not a power supply problem.

@Logan_UA - just for clarity- is this an electrically heated glass windshield? - Or is this issue with the cab heater not putting out hot air? or is the cab heater not diverting hot air to the windshield area?

If heated windshield with heater wires, ask relative if in/on the glass; is there any odd spots along the element wires on glass... bubbles in the attachment tape for example?

those thinking about this==> if it is a heated electrical glass windshield.... would this be a special add on option not normally installed ??? If that is the case then would any relay's etc.... maybe NOT be in the PDP but elsewhere instead??? .. or if would still be likely at PDP..... would relay put in a place on the board reserved for "add on/special service items???

Just thinking out load to see if it gives anyone an AHAAAAAAAAAAA moment.

coachgeo said:

@Logan_UA - just for clarity- is this an electrically heated glass windshield? - Or is this issue with the cab heater not putting out hot air? or is the cab heater not diverting hot air to the windshield area?

If heated windshield with heater wires, ask relative if in/on the glass; is there any odd spots along the element wires on glass... bubbles in the attachment tape for example?

those thinking about this==> if it is a heated electrical glass windshield.... would this be a special add on option not normally installed ??? If that is the case then would any relay's etc.... maybe NOT be in the PDP but elsewhere instead??? .. or if would still be likely at PDP..... would relay put in a place on the board reserved for "add on/special service items???

Just thinking out load to see if it gives anyone an AHAAAAAAAAAAA moment.

Click to expand...

Hey coachgeo,
Thank you for replay!


The heater, which blows hot air on the windshield, is working.

There are thin wires in the windshield itself, and two contacts come out of the glass, everything is fine with them too. There is also a button on the instrument panel that turns on the heating of the windshield wires, but when we press this button, it only flashes once and does not light up, and the glass does not defrost.

That is, the heating of the windshield of those "threads" or wires that are "filled" with glass does not work.

As an option, we thought that we could find the relay by sound, it should click when it is turned on, but there are no sounds when we press this button. Apparently, this is logical because only the turn signal relays work with sound.

P.S.
Guyfang, TomTime, thank you for moving the thread TBH I I haven't really learned the structure of the forum yet, that's why I missed the right section.

Logan_UA said:

Hey coachgeo,
.....The heater, which blows hot air on the windshield, is working.

There are thin wires in the windshield itself, and two contacts come out of the glass, everything is fine with them too.

Click to expand...

How did you determine they are fine? Continuity test with a meter? [

Logan_UA said:

There is also a button on the instrument panel that turns on the heating of the windshield wires, but when we press this button, it only flashes once and does not light up, and the glass does not defrost.....

Click to expand...

what flashes? a small light inside the switch orr?

Logan_UA said:

As an option, we thought that we could find the relay by sound, it should click when it is turned on, but there are no sounds when we press this button. ...

Click to expand...

No your first thought is correct... some relays you can hear their INITIAL click on.

Try swapping some circuit breakers of same level if you have not already. Same with Relay's. IMHO look at underside of the panel cover , if their is any markings that show were Circuit Breaker and relay's are ..... look for anything that would hint to be a spot used for wiring in add on's that would not be typical on a basic truck. As in these trucks likely did not get manufactured with heated windshield.... that is likely an add on so its circuit breaker and or relay maybe labeled on the back of the panel with some term used to denote "this spot is for added things" Aux? (Auxiliary) maybe? Granted my brain is thinking civilian vehicles... maybe military typically has most all possibilities already on the panel ??? Im just shooting at the hip here.

Can you measure voltage at swtich.... is it 12v or 24v?

Anyone know if the heated glass is 12v or 24v? Im wondering if they can wire around the dash from the battery's with a new switch, fuse and relay as a work around for now.

Heated Transparent Armor is 24v.

Under the passenger kick-panel is where you will find the control module and the circuit breaker module for the system. Remove the panel and the repair manual states the first step is to try resetting circuit breakers CB10X (position 10) and CB19X (position 19). Then check for operation of the heater.

Also - the manuals for these trucks are electronic and the troubleshooting for these systems is "interactive" and walks you through each step - is there someone your relative could talk to in maintenance to possibly get access to the manual for his truck? This level of troubleshooting is not technically "operator" level and is intended to be performed at the unit maintenance level. I understand if adverse conditions prevent that possibility - just trying to understand the big picture of your situation on the ground.

I fail to believe TACOM can not help here. If the Gov gives these trucks to the Ukraine, I just fail to believe there was no support to go along with it,

Guyfang said:

I fail to believe TACOM can not help here. If the Gov gives these trucks to the Ukraine, I just fail to believe there was no support to go along with it,

Click to expand...

Uhhhhhmmmmm, you ARE talking about the current US Gooberment, correct???? We all know that giving and sharing are good, but sometimes, just sometimes certain people get confused and "forget" things......................ya know, like sharing manuals, 2nd Amendment, up VS down,,,,,,,,,,,,,,,,,simple stuff.

Logan_UA said:

Hey coachgeo,
Thank you for replay!

As an option, we thought that we could find the relay by sound, it should click when it is turned on, but there are no sounds when we press this button. Apparently, this is logical because only the turn signal relays work with sound.

P.S.
Guyfang, TomTime, thank you for moving the thread TBH I I haven't really learned the structure of the forum yet, that's why I missed the right section.

Click to expand...

If you are in a war zone and need to see through that windshield immediately then I would just run 2 wires with a switch from the battery box straight to the windshield.
You must put a fuse on them or you can start a fire.
If you cant play with it and its an emergency then this is an option. Its very likely that the windshield deicer circuit is pulsed by the electronics so it would be bad if you just left it on. Will probably need to pulse it on and off. Its also possible that doing this will damage the vehicle.
If its not an emergency then try and fix it the right way.

coachgeo said:

How did you determine they are fine? Continuity test with a meter? [

what flashes? a small light inside the switch orr?

No your first thought is correct... some relays you can hear their INITIAL click on.

Try swapping some circuit breakers of same level if you have not already. Same with Relay's. IMHO look at underside of the panel cover , if their is any markings that show were Circuit Breaker and relay's are ..... look for anything that would hint to be a spot used for wiring in add on's that would not be typical on a basic truck. As in these trucks likely did not get manufactured with heated windshield.... that is likely an add on so its circuit breaker and or relay maybe labeled on the back of the panel with some term used to denote "this spot is for added things" Aux? (Auxiliary) maybe? Granted my brain is thinking civilian vehicles... maybe military typically has most all possibilities already on the panel ??? Im just shooting at the hip here.

Can you measure voltage at swtich.... is it 12v or 24v?

Anyone know if the heated glass is 12v or 24v? Im wondering if they can wire around the dash from the battery's with a new switch, fuse and relay as a work around for now.

Click to expand...

Hey coachgeo!

Thank you so much for your questions. Seems the answer is already founded in the next message from GeneralDisorder

I am really appreciate your help!