802a Burned Wiring at J7/P7

[Toolslinger]

Ok... Well this came to light here:
No Start - Oil Pressure - 802a

I thought I'd start a fresh thread with a more useful title to keep the further info in.
I haven't gone any further yet really. I expect it may be a slow evolution.

I found someone with a 803a enclosure that had the engine, and generator removed, due to water intrusion/locked up condition. I will probably take a look at that this week. I could see the control box wiring in the photos, and that looked fine, and it might represent some spares of other components as well. I know there's a bit of difference between 802a and 803a, but I believe the harness that I'm looking at would work, even if I had to make the odd change.
I also got an offer from someone here for some of this.

So, I expect I'll be able to come up with parts. I haven't posted a wanted yet, because quite honestly, I don't know fully what I need. I did look in the -24P, but unless I missed it, there's no PN for these harnesses complete. It seems to just tell you what the end connections are, and you build it from the specified wire gauge.

Haven't gotten the machine indoors yet. My tractor that can run a fork is tied up with a firewood trailer currently. I can sling it from a loader, but I haven't really cleared a space in the barn to set it yet. Between social schedule, work, and weather it just hasn't worked out yet. Today, I've got howling wind (~30 mph gusts), which is when we tend to loose power, but I sure don't want to be under the trees messing with it today. I got the old gas fired unit in place in case, but that's the extent of my outdoor time today. Since all the ash trees are dead/dying, any day like today is when you just hear trees crashing down in the woods. Not good outdoor weather unless you're in the middle of a field. No ash over the house, but still not ideal to be out there.

I did pull P7 apart. Unfortunately it does have enough damage that I'll have to deal with that as well. A couple pins from J7 came out when I pulled it.

 

[Guyfang]

NSN: 6150-01-379-0592 30554
Part Number: 88-20256
Nomenclature: WIRING HARNESS, BRAN 60HZ

The MEP-803A Wire Harness will work perfectly. Its just that the wires that go to the engine portion will be longer that the MEP-802A. So cut em off, or coil them.

Do not just look at the pictures. Look at the parts callout too.

 

[Toolslinger]

Do not just look at the pictures. Look at the parts callout too.

I thought I had. Really. I am going to go look again simply to satisfy my curiosity.

 

[Toolslinger]

And there it is... At least that shows me how they've indicated it on the schematic. Now I have the engine side number as well. If I'm lucky, the engine side is still present too.

I still intend to spend time with a meter seeing if I can find anything that caused this. It would be nice to get the replacement harnesses on hand since that may be a bottleneck if I find the time to work on the machine sooner than expected. I expect I could remake everything by hand, but that is likely to be far more expensive, and way more time.

 

[Toolslinger]

The shell I ran across is from an 813a, rather than an 803a...
-24P indicates no difference for the engine side harness, so if that's present, it would be ok.
-24P indicates a different PN between the 803a, and 813a in the control box. Looking at the schematics, and parts breakouts, the only thing I see different in the harness is the 3 wires associated with the convienience outlet. I know there are component differences like relays, and switches, but the wire harness looks the same apart from those 3. If that's the only difference, I can run those seperate, and just bundle to the main trunk.

Have I missed something glaringly different? While I have been staring at this for a couple hours, I fully expect I may have missed something.

 

[Guyfang]

I made a quick scan. I think, I would go for it. I too, did not see any big difference. But you need to know what started your set to burn. If its something you overlook, than you will get to see a second one smoke test.

 

[Toolslinger]

Test everything I can first is the plan.
Then I'll put in the harness, and test some more before it sees batteries.
I should add that I'll be running through contact cleaner as well.
That many wires is daunting, I don't want to ever do it again.

The shell came home with me. Control box looks ok. Engine side was cut sadly. There's enough left that I can splice on my existing, but that's not ideal. No harm since mine is shot anyway, and I only have to splice 1 of 3 plugs. Gauges look ok. Switches look and feel ok. Relays are present. So the parts that cross over will likely go in the spares stash if they test ok. The shell will get sold. The sheet metal and doors look to be in good shape.

 

[Toolslinger]

Well time flies...
Yesterday, it was a balmy 10 degrees out there... Perfect day to do tiny wiring in an unheated garage... At least I put it in my uncle's place which is wind tight. With the propane heater going, it might have gotten above freezing.

The process started with harvesting the harness that ends in J7 out of the 813a. Now, I'm sure we've all looked in the control cabinet, and thought, man that's a lot of zip ties... I'm here to tell you that, yea, it's a ton of zip ties. If you ever need to do this, use/get/buy very sharp, very pointy diagonal cutters. They fit over the tie, and between the wires in the bundle to act as a guide. Obviously you don't want to be cutting wires, and I'd say it's better not to disturb any more than you need to.

Unfortunately, when that harness burned, it cooked the wires right above it that run to the voltage regulator... So more wire needed. That set of wires ends up being connected to J5. Only 4 at J5, but 8 or 9 total involved.

There are 2 wires that run to the diagnostic port, 1 to the fault light panel, and a shielded pair that runs out to the voltage adjustment pot that are not just terminals. I cut those as there's no way I'm messing with those connectors. Everything else is a screw or nut connection.

After 5 hours, I packed it in for the day...

Day 2... 4 degrees... Really?... Well I did a number of errands first, so it was up to 17 when I got back to the 802a...
The hardest part was getting the tiny little screws that hold J5 in place. They're slotted screws coming up from below, and there's almost no room to work, let alone see. Two people would have made it better, but probably not much. Between both machines I couldn't save the 4 needed screws... Found some that are a bit longer, but work fine, so that's done...

I basically started laying the wire back in by bolting down the connection, and then following the burned harness backwards. When I came to a wire the burned bundle, I found the matching number in the new, and replaced it. Almost everything really was perfectly positioned except the 813A didn't have a fuse mod, so I got a little panicky when the wires were not in the right order... Sorted that out, and moved along pretty nicely. I left the 5 splices for last. Good quality crimp connectors, and a really good quality crimper made that reasonable. They're done, and shrink wrapped.

After that, it was just a matter of installing all those zip ties again... The upper wiring is now done. I'm about 10 or 11 hours in to this now. The lower or P7 harness is next. P5 didn't have an issue, so I don't have to worry about that one.

Got a couple more tanks of propane for the heater. I don't think I could have done this without that little bit of comfort. No way you're doing this with gloves on. I should be able to get back at it after Christmas.

So in answer to my earlier question, the control box wiring harnesses from the 813a work perfectly on an 802a. The lower doesn't matter in this case since it was cut, and I'll be splicing.

 

[Toolslinger]

Just because everyone loves pictures... This was almost done resecuring things... Obviously the tails are yet to come off...

 

[Ray70]

I give you a lot of credit for doing that 10* weather! I've done it a couple times on 003's and 802's during the summer and it sucked bad enough when it was warm enough to feel your fingers.... never mind below freezing!

 

[Guyfang]

Looks good!

 

[CallMeColt]

Great work. I had wire harnesses posted for sale FOREVER and they didn't move, so I scrapped them to just browse & see this thread. Had someone local need it two weeks after as well. Looks like I will not being doing that again. My next part out, the harnesses will be saved. Though, at the point, I'm sure it will go a few years before they're needed again but I do have more storage now.

 

[Toolslinger]

Well, on the up side they don't take up a ton of space to store. I think they'd fit in a gallon ziplock pretty well to keep them neat, and from catching on every possible thing they're near...
Instead, I have an entire 813a enclosure to store them in... I'm voting for a ziplock in the future when I scrounge things I don't need this time around.

 

[Toolslinger]

Back at it today...
In my head the P7 harness was going to be fairly simple... I really thought it was just wiring down to the engine. Alas, it runs between the two sections of the control boxes, 3 lines up in to the rear compartment, and then 3 down one side of the engine, and the balance down the other, all the way out to the fuel tank.

I found that while extricating what was left of it from the 813a. It was complete to the control box, and down the starter side of the engine, and then cut right about where the fuel/water separator is.

After wrestling with the 813a, I decided the better choice was to pull the front control box off. More sheet metal headache, but way better access to everything else. My 802a must be old. I haven't looked at the date, but just about every single panel assembles with a nut. There are only a few captive nuts. Just a real delight to get at.


Lots of cut zip ties again...

Wires up to TB4 weren't too bad. Wires back to the starter, and magnetic pickup were easy enough, though I have a question on that...

Is there a polarity to the magnetic pickup?

I kept track of which wire came off each of those two, and the 1/4" terminals are backwards on the replacement harness. I can swap that easily, but I didn't know if it matters. I wasn't quite done today, so no loss leaving it until I can look in to it, and it's readily accessible. I didn't see it in the TM when I was chasing wire destination today, but I wasn't really focused on polarity of that since I knew it already had the terminals on those wires...

All the rest of the lines had to be cut, and spliced. I feathered them as much as I could so I didn't have a giant lump of crimp splices. They're all crimped, shrink wrapped, and secured in the bundle running across the front of the rear control box. I would prefer no splices, but it isn't the worst spot to have done it.


Hosed out the mass connectors with Deoxit. They all look good at this time. Put the front control box back in place and made up the connections.
I was going to start checking continuity on the lines, and the questionable LOP switch. Naturally the battery in the meter was dead. It was kinda late in the day, so I'll start on it again tomorrow, and with any luck start putting some panels back on it. Assuming all appears well, I should be able to hook up batteries, and spin it over on the weekend after the new years break.

Happily, the weather was cooperating today, it was above freezing all night, and made it in to the mid 50's... Way easier to work in a sweatshirt, rather than a parka...

 

[CallMeColt]

Great work & thanks for documenting. Hope you got a bunch of new hardware! I throw away all removed stuff as it's not worth the hassle. That is just me!

 

[Toolslinger]

I got some from the last go around inside. Not enough, and I didn't think that far ahead to get more sadly... On the up side the vast majority of the steel screws, and nuts are in good shape. Anything that's at all sketchy will go stainless.

 

[Guyfang]

Just go down and get all the screws stainless. Might as well, you got it torn apart anyway.
I always carried several hundred screws and nuts of various sizes, and when I had someone's set torn apart, I simply used the good stuff to put it back together. Do that once for someone and they have no problem ordering some to give you back. Good "Public Relations!"

 

[Guyfang]

Is there a polarity to the magnetic pickup? No. Its AC and no matter how you hook it up, it works. You just need to read the procedure 1-2 times and follow it when putting it back in. If you haven't had it out, do take it out. Inspect/clean it and re-install.

 

[Toolslinger]

Is there a polarity to the magnetic pickup? No. Its AC and no matter how you hook it up, it works. You just need to read the procedure 1-2 times and follow it when putting it back in. If you haven't had it out, do take it out. Inspect/clean it and re-install.

Thanks for that. I have not pulled/inspected it yet. I am going to add that to the list that includes the fuel/water separator. My plan is to do these PM/inspection tasks once I finish up this repair. I do not want to disturb anything that was working as far as I know prior to the wires burning. Once I know I got that fixed, I can get on with opening the next can of worms...
I also will be putting in an order for the screws, and nuts. I only put one panel back today to secure the control box frames. I really didn't like the whole front panel feeling floppy.

Other than that, I took care of the magnetic pickup wires today, and finished that bundling. I also checked the LOP switch, and wires with the set dead. I'll do the second test once I can get the machine running per the TM. There's no question the one wire running to the LOP was hot. I hit it with some Deoxit that was handy, and the dark color isn't oil. Regardless, I checked continuity of both wires through the switch all the way back at the relays. All seems happy at this time. Wiring is 100% complete at this time. Reinstalled the relays after cleaning the sockets.

Hooked the NoCo back to the batteries, and put a charge on them. One topped up, and the second is almost there. I'll finish that up next time I'm present. It would be very poor form to burn my uncle's garage down if something went bad with the batteries, or charger... The batteries are at end of life really, but as long as they were topped up, they kicked it over ok. They should be replaced, but that's another thing that is going to wait until I know I'm functional again...

 

[2Pbfeet]

@Toolslinger that all sounds as if you are making great progress. Good luck in getting the unit back up to full service!

All the best,

2Pbfeet