M1088 project, no start. Not even trying!

[thetruckguy]

So I picked up a 98 m1088 tractor and it had a ton of parts missing. I'm pretty sure I have everything replaced, but the starter will not even click. Any advice on where to look first? This thing is a LOT different than my last m931a2!

 

[NDT]

Start by making sure you have the proper p/n relays in the spots. Uncle loves to mix them all up. Visit the TM, there is an easy to use troubleshooting tree there. Does your WTEC light up? If not, that will inhibit cranking.

 

[Suprman]

Didnt you have a thread going before on this? Do you have good batteries and they are connected properly.

 

[scottmandu]

check for tcm function. the starter won't engage without the tcm activating the neutral relay.

 

[thetruckguy]

Yes suprman, I did have another thread about mystery wires under the dash. I have to go on and update it. I did find where they go. Plug J210 was for the winch that I don't have, and plug J108 is for a dump bed that I don't have.
A lot of fuses and relays were missing, and I spent a lot of time researching part numbers to find the correct ones and was successful. I used the chart on the back of the fuse block cover to make sure they were all in the right spot. So that should be good. (If anyone needs guidance finding the relays and semiconductor numbers, let me know)
The wtec was lit up. As was the ear piercing buzzer. We tried to listen for a clicking relay when I hit the starter button, but wound up with our ears ringing from the buzzer. I plan on disconnecting it when I go back to work on it.
As of right now, I have only 2 batteries hooked up. I tried doing so in the proper way so both 12 volt and 24 volt will both work, but I am going to borrow 2 more batteries and hook them up right and see if that helps. Then I guess the next step will be checking the thermal switch.

 

[Suprman]

Make sure you have 12 and 24 volt at the panel posts left side. Check oil and coolant levels. Turn power switch on fold cab. Drivers side frame rail, stand to the right or on the tire, is a contactor relay. Jump the 2 large posts and it will crank. As long as you have fuel and the fuel solenoid is powered it should start.

 

[thetruckguy]

Awesome, thanks! I will try it and get back to you!

 

[thetruckguy]

I got it to crank today by jumping the solenoid on the frame. It was pretty cold (15℉), and it looks like the water separator filter is leaking, so, no start. I am going to replace the water separator and try bleeding the injectors. I am guessing it's not as easy as my m939a2 was. I will try again with warmer weather this weekend. Also still have to find the culprit in the start button system.

 

[Suprman]

The diaphragm in the separator hand pumps go bad. Once you swap that out you can crack the 2 lines at the front of the fuel pump and prime away. Once you see fuel dripping close them and prime more then crank. Repeat till it starts.

 

[thetruckguy]

Also, I checked the thermal switch and it has already been bypassed at the starter. So I will start at the start button and work my way back. And a half a roll of electrical tape later, the buzzer is now tolerable, so I will be able to hear relays clicking.

 

[Suprman]

I wouldn't worry about that for now. Get it running and there are things to check for the no start at pushbutton. It's not a big deal.

 

[thetruckguy]

Yeah, I just want to hear this beast run most of all. I will let you know how it goes.

 

[frank8003]

Yes suprman, I did have another thread about mystery wires under the dash. I have to go on and update it. I did find where they go. ~ ~ The wtec was lit up. As was the ear piercing buzzer. We tried to listen for a clicking relay when I hit the starter button, but wound up with our ears ringing from the buzzer. I plan on disconnecting it when I go back to work on it. ~~

To enable truck to come up to air pressure, silence low air buzzer, find leaks, operate brakes, and be able to listen good, find if it is possible to feed in service air backwards on your truck? Works good on M35A2, I don't know if it will work on M1088 tractor.

 

[Suprman]

You can charge the air system from the front emergency gladhand but you will release the spring brakes at the same time. Best to get it started and build air.

 

[thetruckguy]

Oh, I didn't even think of that. That would be easier! Wouldn't have to hand Jack the cab up either! Thanks

 

[frank8003]

You can charge the air system from the front emergency gladhand but you will release the spring brakes at the same time. Best to get it started and build air.

So it is possible to input service air into gladhand. I took it for granted that if truck is parked for any kind of maintenance or inspection all the tires are blocked, safety + TM's.

 

[Suprman]

Behind the front grill to the left a bit is a check valve. Allows air in from the front red gladhand to charge the air system. 90% of the check valves are rusty so when you put air in, the check valve won't close properly and when you do get the truck running you can build air it all escapes out the front gladhand thru the rusted check valve. It's easy to block off the gladhand and build air but by doing that you inadvertently allow air to feed back into the spring brake release system (intended for towing the truck) and it will roll away.

 

[thetruckguy]

OK, so, I jumped the solenoid after bleeding the fuel lines and with a very slight dose of either it fired up! So it is running now but there are "cobwebs" all over the place. The air brake system isn't working right, and the transmission will not up shift while driving. I pushed the down arrow while driving and it would not go below 3. I also tried up shifting manually and the gear selector will go up to 7 but it doesn't shift. The truck was up to temp before I drove it, and the fluid is clean and full. I did take a picture of the ID plate on the tyranny, I will attach it. Judging by the keypad and module type, I believe it is a WTEC III. Also after messing with it for a while, the push button starter started working, but acted like there is a loose terminal or corrosion in the button. I did find a bunch of air leaks too, and another missing component. It came off of the rear air tank and looks like there is a 2 prong wire terminal that goes to it. It was right above the regulator that comes out of the bottom of the same tank.

 

[thetruckguy]

 

[Suprman]

The throttle cable may need some adjustment. Alot of trans issues are low voltage either weak batts or the alt is not charging. It wont let you downshift into a gear that would cause over rev while moving. Sometimes you just need to run it hard to get the trans going again. Post a pic of where you think something is missing.