Hi i was working on my 1984 6.9 IDI replacing my fuel cutoff solenoid and after i was done i went to start it up and i saw smoke coming from the engine. I looked and it seemed one of the wires melted the outer insulator sleeve and now it wont start. The wire is second from the left toward the cab top of the harness. The harness looks like it goes to the glow plugs. Any ideas on this?? Any help would be greatly appreciated thank you. Dont know how to insert pics but i do have some of the wire and harness.

 

Do you mean second terminal from the left top of the big harness plug?

Aha, I see now that must be the one you mean, it's in your hand, correct? The photos are very small but those will do. I was able to enlarge them.

That part of the wire that is completely toasted is FUSIBLE LINK WIRE. That is exactly what it is supposed to do to protect the components in that circuit if that circuit has a short in it.

Now look on the other side of the fuse link on the side where you were standing. That wire is red, can you tell me the color of the stripe is? Lightly clean it off first with a wet paper towel and some dish soap so you can clearly see the color of the stripe. Knowing that I can probably quickly find out where it goes and what component(s) are in the circuit.

ALSO NOTICE : The insulation on that red/(unknown color of stripe) appears to be split open. It's difficult to tell for sure from the photo. Examine that wire very carefully for any signs or arcing. If the conductor strands (copper wire) is exposed that may have shorted out to something metal that was ground(ed) and caused the fuse link to burn up.

Hopefully this will be all that simple but probably not. You'll have to replace the fusible link once we know what caused it to burn out and fix the cause first. It's likely to be related to something that happened to it while you were replacing the fuel shut-off solenoid.

Let us know what color the stripe is and it will be quicker (for me anyway) to find out what's in that circuit and what the problem might be.

Meanwhile after a break I'll see what I can find in wiring diagrams.

 

[QUOTE=Fixnstuff;17329168]Do you mean second terminal from the left top of the big harness plug?

Yeah its the one in my hand that burnt. The color looks like a light green possible yellow. i took a pic hopefully you can tell. Yes top left on the harness second wire. i bougt a inline fuse wire could i replace the fusible link with that connected? Or where will i be able to find a replacement of the original? Your help is greatly appreciated trust me.

 

YES that's a R/LG wire. Red/LightGreen stripe. I know where that goes from looking at diagrams but I am WAY TOO TIRED to pursue this at 3 AM and I have a tough schedule tomorrow so not sure when I can get back to this.

EDIT: What I wrote below may be incorrect. It's based on a wiring diagram from the 1st edition of the 87-91 factory shop manuals that are a mix of 84-86 trucks/vans and 87-91 printed in July 1986 when they were starting production of the 87 trucks/vans. They had not competed changes in the manual for the new design series (1987) so much of it is from 84-86 with some changes for 87. I've found significant errors in these diagrams before.
This morning I found some crude wiring diagrams for 84-86 that I downloaded from this site. Originally from The Diesel Stop site. - they are very blurry and very difficult to read. So far it's showing that the R/LG wire goes from ignition switch to Glow Plug Controller. I'll see what else those diagrams show. I'll leave what I wrote here in case this is correct and I'll try to post a diagram or two later.

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In short, that R/LG wire from the opposite side of the harness connector (Opposite side from the burned out fuse link) which is where you will be looking for the problem, goes to these components:
The Fuel Shutoff Solenoid (FSS). The positive wire at the FSS connector should also be R/LG - You can confirm that (?)
Follow that wire and covering back and down below the Cold Idle Solenoid you'll see a splice in the harness where it branches out to more connectors. The connectors coming off of that same R/LG wire (that goes to the FSS) are:

Engine Temperature Switch which when engine is cold, allows current to flow to these two components:
Cold Idle Solenoid (aka Fast Idle Solenoid)
Cold Advance Solenoid.
After engine is up to operating temperature the Engine Temperature Switch opens the circuit (no voltage to those two items) but at start up they are enegized.
Something is shorted to ground in that circuit causing the fuse link to burn up and you have to find out where that is occurring and THAT has to be fixed before you can put another 20 ga. fusible link in. NOT before you find and fix the problem that caused it or you'll just instantly burn it out again.

If you know how to use a test light and/or a volt-ohm meter (and you will need at least one of those - preferably both then you can find the problem, with some help. Just start by visually inspecting those wires and connections I mentioned looking for any signs excessive heat at the connectors or any places where the wiring could have shorted to ground.

The image upload feature for some reason cannot locate the .jpg image file that I have in a desktop folder of the wiring diagram I used so I'll have to figure out what is going on with that LATER TODAY whenever I can get to it and I'll post it.

You are not ready to think about that yet. Not until you trace down the problem and fix it! I don't know what you bought "inline fuse wire?" doesn't say much. Is it 20 ga? You know it needed to be 20 gauge fusible link, right? Ok , put that off until the problem is located and FIXED. then you have several options, the simplest is bypassing the connector with a fusible link wire, to PROPERLY CONNECT AND SOLDER to the wire on each side of the plug. Otherwise you have to separate the plug and remove the pin for that wire, connect a new pin onto that end of the new fusible link just like it was originally, insert the new pin into the connector and plug it back together. That's if the OTHER SIDE of the harness connector, the female side for that wire pin is good and not burned up.

There are videos on Youtube on how to replace fusible links. 'Chris Fix' for just one example has a pretty good one.

I'm too tired to think about this but don't worry now about how to reconnect the wire with a new fuse link, that's the least of your problem. You can't do anything with it until you locate and fix the problem that caused the fuse link to melt.

If I repeated myself it's because I'm too tired to think.

Have a good day and I hope you find the problem right away. [Ask Yourself]: What exactly did you do while replacing the FSS? Everything you touched, connectors, wires moved etc. might lead right to the problem.

Dang. 4:08 AM.

 

I edited my post above to add the following:

What I wrote may be incorrect. It's based on a wiring diagram from the 1st edition of the 87-91 factory shop manuals that are a mix of 84-86 trucks/vans and 87-91 printed in July 1986 when they were starting production of the 87 trucks/vans. They had not completed changes in the manual for the new design series (1987) so much of the wiring diagrams are from 84-86 with some changes for 87. (a mix between both series). I've found significant errors in these diagrams before.

This morning I found some crude wiring diagrams for 84-86 that I downloaded from this site. Originally from The Diesel Stop site. - They are very blurry and very difficult to read. So far it's showing that the R/LG wire goes from ignition switch to Glow Plug Controller. I'll see what else those diagrams show....

Nothing more than that. They are not readable. I searched at The Diesel Stop to try to find original copies - no success.

Is the wire at the FSS connector and/or Temperature switch R/LG?

If not you are going to have to trace that circuit by following the wire through the harness.
Look around the glow plug relay for a R/LG wire.

NEXT I will look at another diagram that I have - the branch circuit of the R/LG wire from the ignition switch that I didn't look at before. Maybe that circuit goes to the glow plug controller. I'll get back here with it in a few minutes.

 

YES, the other wiring diagram shows that the R/LG wire from the ignition switch also goes to the GP Controller and the Diesel Warning Lights.

Exactly where it goes to the controller or glow plug relay on the 84-86 trucks I don't know and no time left today to try to find it.

Here are the two wiring diagrams that I am using, in the order that I discussed them before. I hope that someone else will jump in with some assistance/advice. Keep us posted on your progress. Next steps will probably be using a test light or meter to find the shorted circuit(s) Others with more experience will be better at that diagnostic procedure than I am:





Note: The ignition switch is shown in the upper blue box. The reason you see the switch duplicated so many times in the box is because all of the wires/connections at the switch can not be shown in a single diagram of the switch, so it is duplicated 5 times in the second image, each showing different wires that come off of the same single switch.

The R/LG wire circuit is to the left in each diagram. 'S' means Splice, such as S216.
'C' means Connector, such as C129 <--that is the harness connector where your fusible link burned up and this connector is shown in the first diagram right below the 20 ga. Fusible Link that goes to the FSS, etc.

Hope these will help and keep us posted on your progress. Actually you can probably start using a test light or meter to start looking for the shorted circuit if you can't find the problem visually.
That will also help to confirm that you got it fixed and there isn't another issue in the circuit.

I hope that someone else with more experiences can help you with that. It's something you need to learn to be working on vehicles since wiring issues are common.

 

Hey thank you so very much for your help fixnstuff without your help i would not know how to atleast start this task. I think I might know what i did wrong but i have to follow those wires from the female side of the harness to each componet they connect to. Again thank you so very much for your help on this. I will update as i try to figure this out.

 

You are very welcome. I always like to help people it's a character trait that I've had since I was a teenager.

One thing to remember, it's always best to disconnect the negative battery cables before working on electrical. That way there is no power in the circuits and if you short out a wire or component while working on it no damage can be done. Don't put tools on top of the batteries, they could touch the positive post to metal in the truck and make a very unpleasant spark. (It's possible to blow up a battery - I suppose if the tool gets stuck in that position or if there is hydrogen gas from the battery present<-- even if that's not likely it's better to be safe than sorry.

Depending on what you think the mistake might have been you might want to start at the other end of the harness near where the 'maybe mistake' happened. Actually:

IN FACT, what exactly did you do that might have been wrong? If you can correct that or did correct it you might not have to trace the wire, the circuit might be fine if that mistake was/is corrected. The fuse link probably saved you. The circuit wire can be tested with an ohm meter or test light to see if it is still shorted out somewhere. If not you'll only have to replace the Fuse link wire making this a lot easier.

That's my view on it right now, being very tired and not being an expert at this. Seems to make simple sense to me.

So, what did you do that you think might have been a mistake? Everybody makes mistakes and that's one way we learn. At 67 I've learned to try to avoid those. I can't afford to make mistakes that cost money and more work so I spend a lot of time preparing for something I plan to do, becoming familiar any problems that I could run into so I'll be prepared for them and being able to do everything right the first time. It takes me lot longer before I start a job (being fully prepared and knowledgeable/informed before I start) and longer to get it finished because I tend to be a perfectionist in just about everything I do. I have the time for that, I guess, where a lot of people don't. Usually that works out very well and I get good repairs that last a long time. Other times it wouldn't have made a difference so I wasted some time (sometimes a lot of wasted time).

I am rambling I know but one thing I learned in the construction business is that some things look like they will be easy but turn into a can of worms and become a nightmare while other job details look like they might be very difficult with problems and turn out to be easy 'a piece of cake.'

I don't know what any of that has to do with this topic, I'm just 'burnt out' if people reading this are familiar with that expression and just typing what my mind is thinking. Too tired to even try to edit what I wrote.

Anyway, what's going on with that wire problem? WHAT do you think might have caused it?

 

Well when i replaced the fuel cutoff solenoid i noticed there was rubber washers under the screws. I did not replace those cause after i took off the solenoid they just broke. By having those rubber washers there under the bolts for the solenoid do they prevent the grounding out i wonder? Could that of caused it. I didnt do anything else different either when replacing the solenoid. This is however what i think i might have done wrong im not sure.

 

GREAT! That helps alot! I've never replaced a FSS but those "rubber washers" were probably plastic insulators (Old and brittle) ELECTRICAL INSULATORS! (at least one of them) Preventing the FSS from shorting to ground!

Can anyone else confirm that???

This means that the Fusible Link probably protected that wire as it is designed to do! It might have protected the FSS, I don't know how to test that. Should be simply applying voltage to it and if it clicks it's good. I've never really looked at one so I'm not sure how to do that.

This would mean that all you have to do is use a simple and cheap test light to very simply test that wire to the FSS to make sure that it isn't shorted to ground and I don't think it will be. THEN, all you need to do is splice a Fusible Link wire to the good part of the wire on the starter relay side of the big connector, BYPASS THAT CONNECTOR and splice the other end of the fusible link onto the wire that goes to the FSS (other side of the big connector). It's just easier to bypass the big connector because the pin for that wire will have to be replaced and the female terminal will need some attention if not replacement. I don't think you want to add that work. I am dealing with 2 different harness plugs right now to get one good one and that's my advice to you - bypass it.

You can even buy a separate connector for that one wire and use that to bypass the large connector which is even better! You'll be able to unplug all of the wires that way if/when you ever need to and you won't have to cut that wire and splice it again.

You have to test that wire from the FSS side first, THEN somehow confirm that the FSS is still good ALSO you need to have that insulator at the FSS.

I don't know where to get those at the moment but I'll look later

Can anyone else confirm what I wrote above?

Thanks!

 

Ok so im having no luck finding replacement 20 guage fusible link wire any chance i can use a different guage? I found 14 and 16 but not 20. For the bypass im going to use insulated male/female connectors.

 

The answer is NO! 20 Gauge is the size of the wire that protects the wiring in that circuit. If it's a lower number that, it is larger wire that carries more current and will not burn out before the wire it's supposed to protect burns out. That's how fuse link wire works. Its smaller wire than the wire it protects so if the current load gets too high, it burns out before the larger wire in the circuit, thus cutting the power to the circuit, protecting the wire and components on that circuit. IT HAS TO BE FUSIBLE LINK WIRE which has a thick insulation that protects from electrical fires, as well as purified 'low oxygen' copper so it will melt through at a consistent amperage load.

Make sure you get a really good well clamped connection to the terminals in that connector, AND THEN SOLDER THEM!!!!! The reason is those terminals require a SPECIAL crimping tool not the common wire crimper on common wire stripping and crimping pliers. I doubt if you have one of those. I don't, can't afford to buy one. On the OTHER END of the fusible link wire do you KNOW how to connect that?? You CANT use those cheap crimp on connectors! I suggested before that you go to Youtube and look up "Chris Fix Fuse Link" and find that video to see how that is done.
That's one good way to do it, using the wire clamp and then soldering but he wasn't as meticulous as I would be in meshing those two wire ends together. You need a good soldered connection!

You can also, (first, remember to slide some heat shrink tubing of the right size over the wire - you won't be able to get it on after the connection is made) then, tightly twist the wires together (the way that I would do it, not Chris Fix's way) and then SOLDER THEM. Slide the heat shrink tubing over the the soldered connection you just made and apply heat to shrink it tightly around the wire insulation and the connection.

Go to Youtube and watch a few videos to learn how to do these repairs correctly. Not all videos show the right way to do things so look for people who know what they are doing! (some people don't in their videos) Some companies, parts suppliers put up excellent videos on this stuff, splicing and soldering wires and connections for example. Someone who posts a video titled something like, "How I fixed them wire things MY OWN WAY, but it worked good so far" might not have done it right or very well, or they might have done it right or got a good result anyway. Best to watch several good videos to see different methods or techniques. OR you can view web pages with instructions and photos.

Just do it ALL RIGHT the first time now so you won't have to do it again.

What are you going to do to replace those broken and now gone insulator washer(s)???

I guess you'll have to buy some generic ones that fit.


Did you ASK someone at the desk at Kragen Auto Parts (aka Schucks, O'Reilly, etc) to search the computer to see if they could order 20 gauge fus link wire in from their supply warehouse? (Usually next day delivery or same day if you order early enough) Online they list lot's of fusible link wires but not 20 ga. but they still might have access to it. Call all of your auto parts stores first and ASK them to check and see if they can get it. "20 ga. Fusible Link or Fusible Link Wire."

Otherwise order from Summit Racing, probably your fastest delivery option, they will ship the same day:

https://www.summitracing.com/parts/pco-5557pt/overview/

I found this nice one at Amazon.com. 'Nice' in my view because it has that larger diameter molded plastic piece that clearly marks and Identifies that it is a 20 GA. Fusible Link. It's OBVIOUS when you see those. Unfortunately it looks like a SLOW delivery time at best:

Ford dealership parts counter is another quick option! ANY 20 ga. fusible link should work! Pars guy might not know that and wikll look up your truck to see that the ancient part number isn't in stock and possibly they didn't update that particular data to show later model part numberS for THE SAME THING. Long experienced parts guys will know how to find it, less experienced and thos who don't want to take the time to search for it may not find it so just tell them you need a a 20 GA Fuse Link (wire) (A CHEAP ONE, LOL! - as if that's gonna happen!) Might not bee too bad though. ALSO THOSE INSULATOR WASHERS! I don' know if you got your new FSS at a dealership but if so, they should have those insulators! DON'T FORGET TOP CHECK THAT Regardless of whether you go there for a fuse link!

I have a ton of work to get done on my truck in the next 3 days so I have to get off of here!

 

Yes i did watch that video from chrisfix and i am going to follow his way. I have all the stuff to do that. The 20 gauge Fusible Wire i found on amazon so just waiting for it to get here. This past weekend i tried hunting it down at all the part stores, home depot, lowes, orchard supply and nothing. Its ok like i said i found it on amazon for 8$ free shipping. The washers i got at home depot i got the neoprene and fiber washers so i will also be replacing them. Im going to attack this all next weekend. Thank you so very much Fixnstuff for all of your help on my dillema. It is very appreciated i asure you. Without your help i would have been lost trying to figure all this out. Again thank you very much.