No lights to Ellison dash panel

ou812

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I have a M1079 that would not start? It would try if I let it sit for 15 seconds, but every time I turn the power switch on I get the low air siren ,and a clicking sound under fuse panel somewhere? It’s almost like a breaker is triggered due to high amp draw. I hear a click on/off on/off. The lights don’t work or trans display? So me being desperate to get it started I bypasses starter solenoid and she fired up no problem. This truck is new to me ,I could not find schematic for this truck. I’m a John Deere mechanic, but it’s hard to diagnose without the tech manual. I’m hopping someone may send me in the right direction. This unit has series parallel battery circuit that uses 4 batteries. I’m sure I have them hooked up right. Good ground 12.6 out the the middle cable with four clamps and 24 volts out the back two clamps. I noticed there are two wires off 24 volt cables so I’m guessing the starter has two 24 volt cables for supply?not positive. Thank ahead for any help.
 

Ronmar

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What year, A0 or A1? Your description sounds like an A0 and All the A0 manuals are in the manuals section on this website in the present conflict vehicles section.

There are 2 24V lines Off of the battery bank, one goes to the starter The other goes to the polarity protection box so it sounds like the batts are wired correctly.

The first place I always start with electrical problems are the two test points on the left side of the power distribution panel(PDP)/fuse panel. Measure from the 12 and 24 lugs to the ground lug WHILE you turn on the switch. They should have steady voltage as you turn on the main switch. if they don't(voltage goes away or pulses under load) then the issue is a bad connection or a bad diode in the polarity protection box or wiring back to the batteries. This sounds like it would be a 12V problem by the way. I have had a similar issue with a bad connection on the 12V line at the polarity box, would turn on the switch and things would power up, but as soon as I pushed the starter button, the load thru the bad connection would cause a severe voltage drop and things like K2 would start to pulse/click...

if the power is stable at the test lugs unloaded or loaded, then the issue is in the PDP or wiring to-from the main sw. K2 is the main power relay that provides 24V to just about everything else, but the main switch controls 12V to energize K2.

check power at the test lugs and try and identify exactly what is pulsing/clicking in/under the passenger dash and post back here.
 

Suprman

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I would add a large ground wire from the batteries negative and bolt it right to the frame. Make sure you sand all the paint off the frame and use good lock washers. I see this all the time.
 

ou812

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Got good ground

7FE52C6C-7D43-4447-A089-D46ED96153F6.jpg7FE52C6C-7D43-4447-A089-D46ED96153F6.jpg
I would add a large ground wire from the batteries negative and bolt it right to the frame. Make sure you sand all the paint off the frame and use good lock washers. I see this all the time.
I added the nato ground so I show good ground. As soon as I flick the green switch I hear a tick tick tick. It’s a deeper sound than the bosh relays make. It does not like something? It gives me about 2-3 seconds of start time then shuts starter down. That’s when I bypassed the relay. Just know that I have no lights or transmission display, but the heater works? I could not find the tech manual for the m1079 only the operations manual. I’m new hear so it could be staring me right in the face. I still need to check out what Ronmar asked me to check I’m needing to locate polarity box and K2 ?. I just got this truck towed it had no batteries so there is a chance someone hooked up wrong. The picture shows how I hooked the batteries up. The glow plugs and pre heat definitely are not working either, it took me forever on bypass. Another reason I would love to see schematic to find out how that works when pressing red button. Thanks
 
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Ronmar

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Ok, well an A0 doesn't have glow plugs or preheat so we need you to positively identify this vehicle. What year was it made? What Model(A0 or A1) and What engine?

The polarity protection box is designed to protect the vehicle from incorrect battery connection.

If this is an A1 it will have an additional power control module that controls power application.

The polarity box is inboard of the spare tire and K2 is in the PDP.

on this linked page there is a early version A1 schematic. Down about 10 listings is one for 1078 tech manuals. There is no specific 1079 manuals the ten 78,79 and 80 are all covered in one set. If you have an A0 download ALL these. If you have an A1, well that is a little more problematic...

https://www.steelsoldiers.com/forumdisplay.php?119-Present-Conflict-Vehicles-TMs/page2
 

ou812

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It’s a 1994 Stewart Stevenson sn# NH00VZV0282BLB

I hope that helps I’m not sure AO A1? ,thanks so much for the info you guys are great! I’m sure I can track something down, maybe a mouse in there 😊



Ok, well an A0 doesn't have glow plugs or preheat so we need you to positively identify this vehicle. What year was it made? What Model(A0 or A1) and What engine?

The polarity protection box is designed to protect the vehicle from incorrect battery connection.

If this is an A1 it will have an additional power control module that controls power application.

The polarity box is inboard of the spare tire and K2 is in the PDP.

on this linked page there is a early version A1 schematic. Down about 10 listings is one for 1078 tech manuals. There is no specific 1079 manuals the ten 78,79 and 80 are all covered in one set. If you have an A0 download ALL these. If you have an A1, well that is a little more problematic...

https://www.steelsoldiers.com/forumdisplay.php?119-Present-Conflict-Vehicles-TMs/page2
 

Ronmar

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Ok, 94 means it is an A0 and has a cat 3116 engine. No glow plugs or intake air heater, only manually activated ether injector when the engine coolant is cold enough to enable it.

The M1078 manuals you will find at the link I gave you are what you want. The back of the 20-1 thru 20-5 manuals have electrical, air and hydraulic schematics.

My first troubleshooting hints are also where I would start. Start by measuring the 12 and 24V lugs at the PDP/fuse panel, switch on and off and we can go from there.
 

ou812

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Got a bit further today.

Ok I checked the lugs on fuse panel. The 24 volt read 27volts with switch on and truck running, the 12 volt was reading 13volts so all looks good there. Power seems to be coming in to fuses but the only light I could get to work are hazards,and heater. I found the ticking sound there are two white wires coming from the TCM (Allison module) and it runs up to the fuse panel and both go to 24 volt circuit,it is fused. So they are feeding two wires that are fused down to the allison module. As soon as I feed power to it I see lights on trans display for a split second then I hear a tick tock tick tock. I tried powering it with 12 volt cause I thought that seemed odd to feed it 24 volt? It looks like they meant to be there? But I wanted to try and it was the same tick tock tick tock but slower. I did see some mouse droppings but did not see ant chewed wires. I know this thing was driving cause the owner had it registered. I was given this M1079 with 8000 Kms for I need some time with it. It’s just a boat anchor if I can’t get it into gear 🤔 probably a ground problem not sure yet why this trans module is clicking. Thanks for any help. This site is great.
 

Suprman

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Maybe bad dash power relay. The back of the power panel cover has a diagram. If it was me I would replace all the relays and re-seat all the breakers. Sometimes you get a little corrosion on the contacts. And run the batt to frame ground. You can still measure good voltage at the panel but under load the voltage will drop with the bad ground. If you start the truck from the frame solenoid it will run and appear to be fine. Happens all the time.
 

ou812

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I need to find ground sources

Maybe bad dash power relay. The back of the power panel cover has a diagram. If it was me I would replace all the relays and re-seat all the breakers. Sometimes you get a little corrosion on the contacts. And run the batt to frame ground. You can still measure good voltage at the panel but under load the voltage will drop with the bad ground. If you start the truck from the frame solenoid it will run and appear to be fine. Happens all the time.
i pulled the fuse panel right out so I can see the back. There looks to only one fuse related to transmission and it’s not labeled transmission on the back of the fuse panel cover. I follow the wire down to the Allison module, looks like they feed 24 volts into the module. If I take the fuse out and bridge a wire to that circuit there is four clicking sounds that come from it. So now I know what is clicking buy why? Maybe the module is not getting good ground and it can recognize that. If I can find the ground locations for the transmission module I could do a resistance check or give it the ground. Also things that I noticed there is a big 37 or more pin out connector in the far left order dash with aluminium cap that comes off. Is this for diagnostics? This thing apparently ran on road 1 year before I came along. The owner passed away, so he may have done something? it’s odd all head lights or trans don’t work but the heater controls and horn are fine so we have good power and ground to some circuits. I’m going to have to tow this unit out. I put it on a roll off flat deck and it was to high 16 feet to top of cargo box, so now I have to find some way of towing lower to the ground, I was going to pull a drive shaft so we can lift the front and roll on the back! This drive shaft does not look like it’s easy to remove? When I get it home I can rip it all apart and get to know the system. Thanks for any info to help me out.
 

Ronmar

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For towing with lifted front, it is easier to pull the rear axle shafts out thru the rear hubs. There is a big hex head cap(3"?) screwed onto the center of each hub if you remove it, you will see the end of the axle, it has a threaded hole in the end, you can screw a bolt into that hole and use that bolt to pull the axle right out(mark them left and right). With axles removed, the rear hubs freewheel and you can tow with a wrecker lifting the front end.

Yes, the big covered connector under the drivers dash is for test equip. it doesn't do much though as it is not connected to very many systems.

The CB that powers the trans is CB79, which gets its power from K2 which turns on by the main power switch. If you have replaced/bypassed CB79 and the power is steady at CB79(dosnt pulse with relay clicks), then you may have a VIM, Transmission controller or associated wiring issue.

The VIM or Vehicle interface Module is the module under the power panel behind the passenger kick plate. It is a box of relays and some power conditioning and is how the transmission controller(drivers dash) connects with the vehicle. As an example, One of the relays in there is the neutral start relay. Unless the trans controller powers up and is in neutral, that relay will not energize to complete the starter control circuit. The VIM has 2 fuses in it that pass power to the controller from CB79 and CB35 in the PDP. You need to make sure those have good connection and STABLE power(doesn't pulse when relays are clicking).

The WTEC2 transmission controller is located in the drivers dash and is bolted to the underside of the transmission control/display. You need to pull the dash panel up to access it and its connectors. you need to check that those are connected solidly...

The trans controller(and just about everything else in the cab) gets its ground back thru the power dist panel TB2 which is on the under side of the panel and is tied back to that ground test lug on the left of the PDP. The ground test lug is connected to the cab chassis ground strap which connects down thru the cab floor to the right frame rail. The main frame ground ties from the drivers frame rail to the negative starter connection. That neg starter connection runs thru a shunt(current test device) and back to the battery negative terminal. That is why the first test I always recommend is power at the ground, 12 and 24 test points in the PDP, as a bad frame/chassis ground will show as bad power at those test points.
 

ou812

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I wanted to thank you! your response is great. You know your stuff and your message is going to help me a lot once I get this thing home.I hope these are good trucks. Sure is hard start cold not even freezing yet. I’ll get my multi meter and diagnose this thing. Once I get this thing figured, I’ll work on the cosmetics,and sealing it so I don’t get bees inside. I’m kind of excited.
For towing with lifted front, it is easier to pull the rear axle shafts out thru the rear hubs. There is a big hex head cap(3"?) screwed onto the center of each hub if you remove it, you will see the end of the axle, it has a threaded hole in the end, you can screw a bolt into that hole and use that bolt to pull the axle right out(mark them left and right). With axles removed, the rear hubs freewheel and you can tow with a wrecker lifting the front end.

Yes, the big covered connector under the drivers dash is for test equip. it doesn't do much though as it is not connected to very many systems.

The CB that powers the trans is CB79, which gets its power from K2 which turns on by the main power switch. If you have replaced/bypassed CB79 and the power is steady at CB79(dosnt pulse with relay clicks), then you may have a VIM, Transmission controller or associated wiring issue.

The VIM or Vehicle interface Module is the module under the power panel behind the passenger kick plate. It is a box of relays and some power conditioning and is how the transmission controller(drivers dash) connects with the vehicle. As an example, One of the relays in there is the neutral start relay. Unless the trans controller powers up and is in neutral, that relay will not energize to complete the starter control circuit. The VIM has 2 fuses in it that pass power to the controller from CB79 and CB35 in the PDP. You need to make sure those have good connection and STABLE power(doesn't pulse when relays are clicking).

The WTEC2 transmission controller is located in the drivers dash and is bolted to the underside of the transmission control/display. You need to pull the dash panel up to access it and its connectors. you need to check that those are connected solidly...

The trans controller(and just about everything else in the cab) gets its ground back thru the power dist panel TB2 which is on the under side of the panel and is tied back to that ground test lug on the left of the PDP. The ground test lug is connected to the cab chassis ground strap which connects down thru the cab floor to the right frame rail. The main frame ground ties from the drivers frame rail to the negative starter connection. That neg starter connection runs thru a shunt(current test device) and back to the battery negative terminal. That is why the first test I always recommend is power at the ground, 12 and 24 test points in the PDP, as a bad frame/chassis ground will show as bad power at those test points.
 
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