1998 M1078 A0 Wiring nightmare?

[Suprman]

The black panel is a1 c7 data bus with wtec4 or 5 keypad. Won’t work on a first gen 3116 truck or an a1 3126.

 

[wheelspinner]

That is a mess. You need all those harnesses replaced. No way around it.

 

[NDT]

That is a mess. You need all those harnesses replaced. No way around it.

Maybe not. He has one of the two WTEC plugs, just splice matching color wires (solder with heat shrink, no crimp connectors), find the missing WTEC connector, same. Then the behind the dash harness, he has a cut-off of that as well, seems like armed with the schematic diagram and a test meter, someone could match up the wires. Next, the VIM, again obtain the VIM along with cut off plugs and match up. With any luck, drive away.

 

[Suprman]

First thing you need to see if the engine runs. 24v at the fuel solenoid and starter and you can crank it with a clip lead at the starter solenoid. I would check fluids and filters first.

 

[DREDnot]

First thing you need to see if the engine runs. 24v at the fuel solenoid and starter and you can crank it with a clip lead at the starter solenoid. I would check fluids and filters first.

That's where I want to start. Verify the engine and trans models, and then get it fired up to make sure this isn't just a parts heap. I do wonder why they hacked the electronics out, though.

Seems to be a complete truck otherwise

 

[Suprman]

You may never know why the harness was hacked. The first gen truck dash harness and power panel is one piece. If the harness is cut it all needs to be replaced. What year is the truck?

 

[DREDnot]

You may never know why the harness was hacked. The first gen truck dash harness and power panel is one piece. If the harness is cut it all needs to be replaced. What year is the truck?

 

[Suprman]

1998 would normally be wtec3 trans control.

 

[NV555]

I you need the harness i have several as well as most of the electronic components for tbe cab.

Tim

775 338 0960

 

[DREDnot]

Ok. Dug into it a bit today. Oil and antifreeze were good and full. Hooked up batteries and got the starter to turn it over a couple dozen revs. So far so good.
These were the data plates found on the engine...





Injection pump...


And the trans...


Fuel tank was empty...yet remarkably clean. We are going to put some fuel in it and try to prime the system. I saw a little bulb primer pump on one of the filters. Is that the SOP to prime it?



And is this the fuel cutoff solenoid? I need to jump 24V to one of those terminal, correct?


Noticed this big hose coming off another (fuel) filter...It looks like it was cut, or is it just some sort of overflow/dump tube?

 

[coachgeo]

need more of the plate of the allison number. front edge not visible and the bottom number stamped has a glare so can't read it. Looking for a number on plate that shows any of the numbers in following quote

" The Allison 3070 SP seven-speed transmission[SUP][1][/SUP] fitted to A1P2 and A1R FMTVs has also evolved with the FMTV, its A1 designation being MD 3070 PT, its A0 designation being MD-D7. ...." (from wikipedia) A0 SP 3700
​

 

[Suprman]

First gen truck. Mechanical engine. Put fuel in the tank and pump away at the primer. Its a recirculating system but sometimes you have to crack a line at the fuel pump to bleed it a little.

 

[Ronmar]

Yes that is the run solenoid on the side of the governor in your pic. That big hose over the secondary fuel filter that runs down is the crankcase breather(part of the filter mount assy).

On top of the secondary fuel filter you will find a plug, you can loosen that and pump the primer until you get fuel out which will purge most of the air from the system and should get fuel thru/to the mechanical lift pump in the governor. If you pump and pump and don't get anything, remove the primary filter and check the flapper type valve up inside the housing. if it is fouled the primer wont lift fuel from the tank(mine had a horse hair or bug leg stuck in it) For extra credit you can loosen the 3/8" return hose that connects to the elbow and block(the block Is the fuel pressure reg) on the top front of the governor(upper left corner of pic 7 in the last group of pics you posted). If you get fuel out there you have fuel all the way thru the cylinder head... That and provide power to the solenoid on the governor should get you a running engine when cranked...

Since you don't have gauges, if it starts, over by the shock mount on the passenger side you should have some oil sample valves. if you have oil pressure you should be able to push on the engine sample valve and get it to squirt oil...

 

[DREDnot]

need more of the plate of the allison number.

 

[Ronmar]

Looks like they just didn't want to clean it, so they sent it to DRMO

 

[DREDnot]

I really appreciate the guidance on this, guys! Im slogging through PDFs of the TMs with a mouse that wont scroll up...

Trying to understand the way the fuel delivery system functions and Ronmar's clue that that block(orifice tube?) is the FPR was a BIG help. Now the rest of the hardware is making sense.

 

[DREDnot]

Looks like they just didn't want to clean it, so they sent it to DRMO

No kidding. Ive been wrenching for 40 years, and nothing transfers its filth to me like an army truck.

After messing with it for three hours before work yesterday, I was so grungy that my boss asked me what happened...I told him a garbage truck ran over me

 

[Ronmar]

Ronmar's clue that that block(orifice tube?) is the FPR

If you disconnect the line and unscrew the elbow from the block you will find a spring and a sliding core. very basic pressure reg nets you about 15PSI when idling and 60PSI at higher RPM measured at the T on the secondary filter. If your bulb is working you should be able to push fuel thru to this point...

 

[coachgeo]

hmmm..... ok..... you guys know more about this than I...... since it has an MD 3070 PT allison ... does that make it most likely a wtech III?

 

[Ronmar]

II or III...