M1078 No Start...Not even trying.

Just a quick picking of the brains before I start any unnecessary troubleshooting. I am resurrecting an M1078. Installed four new 31 series batteries, all new circuit breakers, semiconductors, and relays. She's breathing, but won't even try to crank. All four batteries show 12 volts, volt gauge reads about 25, main switch does activate panel (I disconnected alarm for sanity's sake) and there is power at the start button. All wires/ connections look good inside cab and on engine. However, I have not installed the trans ECU and selector. Given the interaction with the Trans ECU and engine, would the ECU's absence cause this? Any other quick tips? TM suggests checking compressor, but it seems the engine should still turn.

First thought is the thermal switch in the starter is bad. In another thread is a pic of the bypass I did. S&S was aware of the issue and had done a similar jumper wire at the starter itself. Mine was easier.

IF your truck has a 3116 engine, there are no computers to keep the engine from starting.

Were you able to put the battery box cover back on? What I remember is that 6TL was a lot shorter than almost every other battery, and I couldn't install the cover

I would plug in the Trans ECU, neutral safety switch/selector not in neutral will keep the starter from engaging.

DSD277 said:

First thought is the thermal switch in the starter is bad. In another thread is a pic of the bypass I did. S&S was aware of the issue and had done a similar jumper wire at the starter itself. Mine was easier.

IF your truck has a 3116 engine, there are no computers to keep the engine from starting.

Were you able to put the battery box cover back on? What I remember is that 6TL was a lot shorter than almost every other battery, and I couldn't install the cover

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Ok. So, I went to the starter relay and checked the supply side. Got 25V. Then I switched my connections to the starter side, went to hit the start button and got nothing. Rechecked my connections, still nothing. Thought I'd try once more for clarity, my alligator clip slipped, shorted, and fried the wire from the hot supply and the lower small connection. AAAAHHHHHHHHHHH!!! I'll fix those tomorrow. Hopefully that was the only damage and I can pick-up where I left off. Since I didn't get any power from the "switch on" side, I think we may be on to something.

As for the trans ECU not being hooked up, I read that with no power the transmission goes into neutral. I saw on another thread that it should start in this condition. Of course "should" is always a loaded word. I'm waiting on my ECU so I can't hook it up yet.

As for the battery box...Yeah that's an issue. I was so proud that I was able to cut the spacing blocks in the battery tray in a way that actually held the batteries in place and looked neat; like it could have been built that way. I was even able to get the cover locked down. Everything was great! Until I connected the cables. Now the retention/ spacing indentions on the lid conflict with the cables. I haven't decided what to do yet. I'm focused on getting the truck running. The easiest thing I've thought of so far is to cut out the indentions that are in the way and make a cover for the lid out of aluminum tread plate.

The pic of the jumper is here.
http://www.steelsoldiers.com/showthread.php?108761-Oops-I-won-an-m1088-tractor/page5

I also was wondering if you had the right relays with the right voltages in the right sockets. If yours is an older truck, it is easy to put the wrong voltage relay into the wrong socket. iirc, most are 12v and a few 24v. This pdf has the distribution panel layout, the relays, voltages and the circuit breakers. I used ATO fuses because it would be quicker to see if I had a bad circuit. I n the early days of me working on the M1094, I put the red arrows next to the relay/circuits I thought I needed work to, to start the truck... I had no relays or CBs , so I overdid it a little for safety sake, and later, added more relays and fuses as I verified circuits. If you haven't done so yet, you may want to read my thread on my rebuild of the Flying Dump Truck. I tried to document everything I could for others as there was very little out there on these trucks when I started.

On the battery front, I've only used 2 batteries and now only a 6TL and (Ithink) a 24N ???. I need to check, but Optimas group 34 without the spacer may fit in the tray and allow the cover to fit. Anyways, that isn't high on my priority list.

Lastly, just curious, was your truck a WTEC II or WTEC III ? The trucks are wired differently for each and not directly interchangeable.

Thanks for the info! I will definitely review your project.

As for the batteries, I didn't do 6tl because of the cost. I couldn't find anyone locally with any 6tl blems. I thought of trying two, but being my first crack at an MTV I could just see something driving me crazy because of a wacky battery set-up that needed all four. Lesson learned there. I'll revisit battery selection and better educate myself on what these big trucks need.

I thought about the relays as well. I double checked them against the decal on the panel cover and the TM, but I'll look at what you have as well. I know the ignition relay is a little confusing because it says 24v ignition, but takes a 12v relay according to the decal. I'm also been a little confused as to your last point. Everyone I've talked to, including two transmission shops say it should be a WTEC III, but I have no wires/connectors on the panel for the WTEC III labeled spots. I guess that harness could have been taken with the ECU, but it leaves me nervous. What are you running? If a III, do you have relays in k25, k26, k34, or k37 (pto, which will not be on all)? You know, It's entirely possible that the panel cover I have didn't really belong to my truck.

The easiest way to find out if you're suppose to have a WTEC II or III is to have you remove the kick panel underneath the power distribution panel and look up at the sheetmetal under the distribution panel and see if you have a VIM. A black plastic box with "Allison" on it. If it is there, you have a II, if it isn't, then a III. At this point I should say that you should add to your sig line the year and model of your truck. My distribution panel is not pinned out the same as what the MTV TMs says it should be. I also don't have a "cheat sheet" on my panel cover . I had to do everything the hard way. Also from the first day I bought my truck I heard nothing but negative comments on it and FMTV's in general...
thought I was in a remake of "Kelly's Heros"....'.enough with the negatives vibes'

No black plastic box that says Allison. So I guess it is a III. I've seen some of the negatives as well. I guess some people just can't accept change. It's like muscle car guys vs. super cars, NASCAR vs. F1, etc. I like and respect it all. I want to learn as much about the MTV series trucks because they are a big part of the future of the hobby. Personally, I think your rig is pretty sweet!

GTR0419 said:

. I want to learn as much about the MTV series trucks because they are a big part of the future of the hobby.

Click to expand...

Bingo! I wish some of the suppliers would start sourcing the parts for these! It's not like they are not being made anymore.

10-4 on parts availability. So far, I have been able to find most of the things I've needed. As DSD277 said, Google has found a few things and there are actually some commercial/industry websites that will search and cross-reference part numbers and then solicit prices for you. I found most of my electrical that way. Allison and the trans electrics have been the biggest PIA. I think the parts will start to show up more now that more of the trucks are being liquidated. Some eBay sellers have parts, they just don't know what they go to. I actually found a tie-rod at a great price. Seller didn't know what it was for, but did have the part # listed.

...Haven't got it started yet. I have to repair the wires I fried. I did have another thought...would the oil level sensor keep the starter from engaging and how sensitive is it? The truck does have oil, but is a little low.

Is the emergency no start button resent? It's in the dash on pass side?

Thanks for keeping me sane on the oil level sensor. My wife's car recently developed an oil leak and practically drug her out of the car a whipped her when the level got low. So, it was on my mind. I haven't had time to work on the truck this week. So, everything stands as it was. Hopefully I can get back to it this weekend.

I have cycled and reset the start inhibit switch with no change. It does "click" when pushed. So, I assume it is functioning and not "stuck".

I will keep you posted.

OK...Wires are repaired and I'm back to were I started before the "barbecue." I had already replaced all the fuses, relays, and diodes/CPUs (they were missing), but double check voltage on the
recommendation of DSD227I. Everything was good.

I went to a local Allison dealer today on the hunt for info and came away with a lot. They were very helpful. First, it would appear the truck is a WTEC II rather than a III. It can actually run both, but the installed harness is for a WTEC II. As the WTEC II is older and the doesn't seem to be in great supply, I'm going to look into how difficult making the change will be.

They also confirmed, as someone stated earlier in this thread, that the truck will not even think of starting without the ECU or VIM. It doesn't matter that the transmission shifts to neutral without power. If the engine doesn't receive the signal from the trans, it will not engage.

So your VIM was also missing on your truck?
There is a way to start the truck, but I'm not going to tell anyone if they don't already know how to...

I'm reposting this with an explanation to what and how the thermal switch in employed in the starter circuit.

The jumper wire on the auxiliary starter relay in the photo is the grounding side of the trigger of the relay. Instead of going directly to a chassis ground, originally it is routed back inside the back plate of the starter motor to a thermal switch mounted inside the plate and back out of the starter to a chassis ground, The jumper wire only removes the thermal switch from the circuit. The factory method of bypassing the thermal switch is to cut the wires going to and from the thermal switch and splice them together.
I was told of the factory repair method while talking to a BAE service manager... this was months after I had done my repair.Failure of the thermal switch was a known issue and this was the easiest repair. Otherise, the starter motor has to be removed and the back plate with the thermal switch had to be replaced.

BTW, the moderators should take this post and lock it at the top of the FMTV section. This will be an ongoing topic now that the FMTVs are coming out in mass

Just posted this on my transmission help thread, but copied it here for anyone following that might also be interested.

"OK...I'm going to have to write a nice detailed "overview" of the MTV transmission saga at some point. As frustrating as it has been, it has definitely given me some valuable knowledge that will help me and potentially others going forward. For now, just know that the transmission data plate and serial number are NOT the defining factor when it comes to outfitting your MTV (and probably any WTEC equipped vehicle) electronically. You need to take the serial number to Allison/Allison dealer and get a "Registration Information" print out. That will give you the customer part number. Allison can then look that up and tell you how your transmission was set up for a specific vehicle. DO NOT ASSUME ANYTHING BASED ON PRODUCTION DATES, TRANSMISSION SERIAL NUMBERS, or vehicle. There are many different potential set-ups. In the case of my vehicle, the Army actually went backwards rather than updating the transmission electronics. That is, the truck was re-worked in 2007 and the transmission is a WTEC III TID 3 (Gen 3), but was "reverse engineered" to run the old WTEC II. Nobody seems to know why other than possibly trying to use up overstocked parts. It's maddening because Allison had actually stopped making WTEC II parts at that point. It can be converted to a WTEC III, but would require all new harnesses including the internal.

Anyhow...the correct parts are now on order."

Yes the VIM is missing as well, but they are not that hard to find.