1998 M1078 A0 Wiring nightmare?

[DREDnot]

looks mostly plug and play to me on this side and way easier than the reconstruction another gentleman has undertaken just recently.

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Today's progress report...
Got everything plugged back in. Put some power to it. No POOFs. No sparks. Master switch made a relay click. Trans controller fired up and gave me a N N.

Tried to crank...nothing.
I realized that there are at least two circuit breakers and two relays on my bench back home.
Maybe tomorrow will be the big day...

 

[coachgeo]

One step at a time....... once you get the wiring all fixed up...... then you will begin the journey in discovering why it became a parts truck in the first place. Just be prepared...... this may be a long journey.

 

[DREDnot]

Yeah, I'm fully expecting something catastrophic. Not my first rodeo trying to raise the dead. I'm about 8 for 10. 10 for 15 if you include the motorcycles.
I was encouraged by the fact that it was complete and intact. Nothing else was disassembled or missing. There is a new drivers door and some light crash damage that looks like it pinched the drivers door shut but that could be unrelated. And the engine fired easily with ether in the air cleaner. Ran smooth and quiet.

Fingers crossed

 

[Suprman]

There are relays in the vim module that can prevent crank. If you turn the dash switch on and the trans control comes on, and you have power to the fuel solenoid, then go to the drivers frame rail and jump the aux solenoid to crank.

 

[DREDnot]

Success!

Had to pull all the Circuit breakers and relays and function test them all to make sure I didn't have to chase stupid gremlins.
I finally got a 30V power supply to test the 24V relays.





Got the 24v segregated from the 12v
Got the four pins segregated from the

five pins.
Verified the correct number of each and plugged them into the proper sockets
Replaced all the circuit breakers with regular fuses.





half successful power up revealed that I missed the VIM power fuse so no neutral start signal.

Once That was sorted out, There was still no crank, just the start relay clicking.

Digging into the world of the AUX start solenoid, I discovered that the ground for the solenoid was cut.



It used to go to a thermal protection switch in the early style starters.
Later replacement starters eliminated that switch and part of that install was to bypass that switch by cutting off the connector and stripping and connecting them together to complete the ground for the AUX solenoid to function
From the looks of things, It may have had the bypass done shoddily may have worked loose and caused a "no start" complaint that sidelined this thing.
I put a crimp connector on fresh clean wire and It fired right up!

Quick function check of the trans/controller had it shifting from neutral to drive to reverse and back to neutral with corresponding indicators functioning as well.

Good oil pressure. Compressor filled the tanks in about three minutes and extinguished the buzzer and warning panel lights. Held at max pressure(100) and the pressure relief valve was heard popping off a few times.

Gave the brakes a few cycles and they seemed to be functioning(in neutral).
Cycled the park brake and trailer brake valves and they seemed to make the expected big rig sounds.
Horn works.

Volt gauge showed 24v(in the yellow). We have four old small car batteries with an unknown state of charge so they may be needing to charge up?

I only ran it for three or four minutes so I didn't see any movement of the temp gauge.

Tried the lights and nothing was lit. So that's a separate project. I doesn't have a flasher unit so we have to find that first anyhow.

So, All in all, a good day.

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[Ronmar]

Cool! Alt output is low, what did the voltmeter read before you cranked it? The first check for that is if the alt is receiving excitation from Relay K11. This should happen as soon as the oil pressure light extinguishes in the annunciator panel after start...

 

[DREDnot]

Alt output is low, what did the voltmeter read before you cranked it? ..

It was reading a needles width below 24v mark. After start, is moved to about a needles width above the 24v mark.
Next trip out, Im gonna start going through the troubleshooting chart.



Our battery collection is sketchy, but functional

 

[Suprman]

Those batteries are not hooked up correctly.

 

[Ronmar]

The ground lead isn't connected(nearest/outermost - terminals) but the rest looks OK...

 

[DREDnot]

I pulled the two ground terminals off to let it sit till I go back. I plan on going through the battery harness and cleaning all the stacked terminals. They are just setting in there for diagnostic purposes till we confirm mobility with a few laps around the compound. After that we will get the battery bank squared away.

 

[Suprman]

Ok. I was wondering how it ran that way.

 

[DREDnot]

Got it moving and took it for a short drive. Got it to shift as high as 6th gear. The initial shift from 2 to 3 takes too long, but the rest seem to shift normal. Headlight switch is bad but lights work otherwise. Air/hydraulic system raises the cab, cab lock works, air bags work. About all that's missing is the turn signal flasher unit, and I need to install the CTIS controller and see if that works

Sent from my SM-G970U using Tapatalk

 

[Suprman]

The 2-3 shift is normally like that. If you really rev the snot out of it, then it’s a little better.

 

[Ronmar]

Yea, you may need to have it relearn the shift points. You have come a long way with this truck.

There is no cab lock. Are you referring to the folded bar assembly on the right frame rail? It doesn't lock the cab it keeps it from over-extending. In normal operation the cab should not tilt far enough forward to fully extend/unfold it. Did you get a big lurch out of the cab when it passed over the balance point(not supposed to do that either)? The rod end where the hydraulic cylinder attaches to the cab is dual function. It has a long slot and a short slot and a sliding cam. At the bottom the cam is aligned with the long slot to allow the cab to float on the air suspension without damaging the lift cylinder or mounts. As you tilt the cab up the cam rotates into the short slot so you maintain positive control of the cab over the balance point... The mechanism is open and needs to be cleaned occasionally lest it get clogged with debris and fail to rotate properly...

 

[DREDnot]

Yes. I forgot about it learning shift points. Ill have to run it a little longer. The cab lock I was talking about is the one with the red pin that locks the cab down. Everything needs to be lubed next.

 

[Ronmar]

Ok, now I am tracking. Still check the rod end for crap... mine was full of sand and grease