Died in traffic - '93 Mechanical IP - Most Electrical Dead

[trbankii]

Had an errand this morning. Started up fine in the driveway. No issues.

Ran my errand. Got back in the truck, started up with no issues, headed back home. Less than half a mile and the truck died. First thing I noticed was that the radio went off, then realized I had no power steering, then realized the truck had shut off and all the gauges were dead.

Coasted to a stop and tried to restart. Nothing. Dead.

Pushed it into a parking lot and started checking things out. Checked out all the fuses under the driver's side dash. Looked in the owner's manual, but that was the only location they mentioned. Headlights and horn work. Other than that, no electrical. Taillights, radio, interior, etc. All dead. But - as I say - headlights and horn work. :confused:

Walked about two miles back home (already 95℉ here and headed up). Trying to figure out what to take out with me to see what I can do with it. Looked at the service manuals for locations of other fuses/fusible links. I'm not sure that I'm clear on all their locations, though. It would be nice if I could just replace something where it sits rather than calling for a tow.

A few years ago I had a battery short out in the driveway. Came out in the morning and everything was dead. But I cannot remember if I tried the headlights or not at that time - I think that they were dead too, though. I did try running a jumper cable from one battery to the other, just to see if that might be the problem again since I do have headlights this time. Still nothing. Besides, if it was just the battery I'd have figured the truck would have kept running off the alternator until it was shut off.

Always something, isn't it?

[trbankii]

Ok, got it home, but still confused... :confused:

Went back and first just tried it again before messing with anything. Despite not being driven far this morning, figured it was worth a shot to try it after it had "cooled down" for a bit. Nothing. No dash lights, no click, no nothing - just the sound of the tumbler turning. Headlights and horn still worked, though.

Checked under the hood. Seemed from the diagrams that the fusible links were on the passenger side firewall. Nothing obviously amiss there. There are two "sockets" there. One fairly large with five wires going into it. The other one opens up and there is a 20amp fuse in there. Unplugged and replugged everything there. Looked around for anything else. Nothing. Tried the ignition. Nothing.

Went back and checked the fuses under the driver's side dash again. Everything looked good the first time, but I figured I'd check them again. For good measure, I swapped the IGN/ECM fuse with another one.

Tried the ignition - the dash lit up - turned the key - and it started right up! Ok, not messing with things here - drove it home. At home, I pulled the "bad" IGN/ECM fuse and looked at it again - more closely. Still couldn't see anything wrong with it. Swapped it back in just to confirm that it was bad.

Nope... It started right up with the "bad" fuse. Ok... :confused:

Further, just for grins, I pulled the ECM/IGN fuse entirely just to see if that would be the problem if it was blown. Nope. Turning the key with the fuse totally removed and the dash lights up. Everything was totally dead before.

Tried unplugging the two sockets on the passenger side firewall to see if maybe I had jostled something there. Nope, dash still lit up even with them disconnected.

Well, it is currently 98℉, they're saying heat index of 102 to 105℉, and the truck is back in the driveway. I'm not going to worry about it right now. When it cools down tonight I'll take a closer look at things.

I'm always a bit more concerned when I can't figure out why something is working again. Always makes me wonder how long it will be until it doesn't work again since nothing was actually fixed. I'm a little unclear on how much of an ECM these things have - if at all. Is there a chance that I "reset" something by leaving the fuse out a bit longer? If it was just a bad contact, I'd think the first time I removed/reinstalled the fuse would have done the trick. And pulling the fuse out entirely should have created the same situation.

[DmaxMaverick]

At first, I would suspect the chassis power fusible link. It works now, at least for now, and they don't heal themselves after they burn. With everything dead but the headlamps and horn, the suspect circuit is the secondary chassis power, which should run from the starter lug up to the firewall. The primary chassis power (headlamps, horn, and some others), runs from the "extra" power lead from the battery terminal or the alternator stud, OR they both run from the starter lug (not sure about the 93). Each circuit has a fusible link.

Don't rule out the ignition switch. The horn and headlamps aren't ign switch dependent, but the IPC, Acc, and engine circuits are. If the ignition switch is bad, you can usually see that it's burned or melted when you get it out.

[trbankii]

Thanks for the thoughts.

I've had a couple situations in my lifetime where a fuse has "healed" itself - sort of re-welded itself together. But as long as this was out and as completely dead as it was, I'd sort of doubt that was the case if it was a fusible link or such.

First thing I had done was jiggle the ignition switch around a bit. Again, there was absolutely nothing. From the time that it died while driving until the time I messed with the fuses the second time, everything was completely dead. Not a glimmer of dash light, not a click of a contact, not a nothing. After messing with the fuses, it started right up like there had never been a problem.

Temperature seems to have peaked at 102℉ (heat index 106℉). It has now fallen to 101℉. But now it looks like there are some heavy storms coming in this evening. It might be tomorrow before I can look at it. I'll start by checking out those chasis power leads.

[greatwhite]

Cant imagine what a mechanical IP 5 speed 93 would use an ecm for.

If it were an auto I would say a TCM, but it's not.

Maybe it uses an ecm to read the sensors and send the signals to some of the dash gauges (ie: drac, speedo, etc) ?

:confused:

[trbankii]

Only reason that I mention the ECM is that is how the fuse is labeled. Could just be a carryover from the gas version?

But the service manual for my truck states that:

The ECM is a multifunction control module that controls the following:

Exhaust Gas Recirculation (EGR)
Exhaust Pressure Regulation (EPR)
System Diagnosis
Cold Advance and Glow Plug


The ECM monitors the following inputs, to allow proper engine control of the above.

Engine RPM
MAP sensor signal used to monitor EGR vacuum
Throttle Position (TP) Sensor Signal
Engine Coolant Temperature (ECT) sensor signal.


So it says that it monitors the sensors and turns on the MIL (Malfunction Indicator Lamp). But it doesn't seem like it has any actual control over my truck other than adjustments to the EGR, cold advance, and glow plugs.

Truthfully, that is more than I thought it had control over for my truck...

[trbankii]

Went out for awhile today to see if I could come up with anything. Truck still starts right up. Couldn't see any burnt/crispy sections on any of the wiring. So I tried jiggling wires around while running to see if I could get it to cut off or at least stumble. Nothing...

Going to have to be careful about where I drive it for awhile until I can either figure out that it was a crazy fluke or figure out what went wrong.

[trbankii]

No problems with some tentative trips around town today - including one trip to the grocery store and the purchase of four three pint cartons of ice cream (remember when they used to be half gallons?). I figure if it would quit and make me walk, a grocery bag full of ice cream would more than tempt the fates... :p

[a5150nut]

No problems with some tentative trips around town today - including one trip to the grocery store and the purchase of four three pint cartons of ice cream (remember when they used to be half gallons?). I figure if it would quit and make me walk, a grocery bag full of ice cream would more than tempt the fates... :p


I like your thinking. . . . . .. .

[trbankii]

Another day with nary a hiccup... Totally baffled by this. As completely dead as it was, I wouldn't expect it to return to completely normal.

[trbankii]

Ok, a week later with no problems since that once.

[trbankii]

One month later, not a single hiccup since that day. Sort of baffled.

[ccc]

trbankii, I have been following this thread, dad has a 93K3500 so I am really interested to see what this turns out to be (not that I hope you have any more issues.) Please keep us updated as you did today. It's good to know it's still running. Good luck.

[trbankii]

I'll be sure to let people know if something turns up. It literally went from absolutely no problems - to - dying in traffic and not starting back up for a couple hours - to - starting right up and absolutely no problems ever since...

As I mentioned above, in trying to get it started I went over a number of things and tried to start it after each "investigation." The last thing I did was to pull and check the IGN/ECM. After finding it good but swapping it with another fuse, the truck started right up.

But, I subsequently found that the truck will start with the fuse completely removed... :confused:

Now, this is going to sound a bit weird, but the last errand that I had run was to answer a craigslist ad. A guy had advertised a few arbor presses. When I got there, he had mis-represented what he had (lighter duty) and was asking $10 more than what he had put in the ad. Older guy, Eastern European accent. I said no thanks, thanks for your time, and left. But he seemed a bit pissed that I wouldn't haggle and the thought has crossed my mind that he put the "hex" on me... Just an odd gut feeling for some reason. :eek:

I'm not a superstitious person, but I also believe there is more to this world than we know or could explain through rational thought.

All I can say is that if that is what happened, it's a pretty nifty trick and I wouldn't mind knowing it myself! :p

[Artworks]

Check the ground at back of the engine near the glow plug relay ( on my '95 anyway) I found that small wire ground was bad and gave me stalling ( quick fix was pulling fuses and reinstalling ??) and also made my air bag light stay on. Check & clean all grounds & maybe add some more ? I feel your pain !!!

[trbankii]

Three and a half months later and not a single hiccup since that day...

[trbankii]

Five months later and not a single hiccup since that day...

[trbankii]

I had made a comment on my calendar - a year ago today was when I had this issue. Since that day, there has not been one single hiccup or anything even remotely similar to the problem again.

Very curious... :confused:

[trbankii]

Ok - 2 years, 9 months, 21 days later and it hiccups again…

No issues up until this morning. Started up fine, pulled out of the driveway turning to the right, straighten out - and everything went dead. Just enough momentum to push in the clutch and drift to the curb so I wasn’t blocking traffic.

Same as before. Everything is dead except for headlights, horn, and dome lights. Tried jiggling various things around and nothing.

Previous thoughts were fusible links or ignition switch. I actually replaced the ignition tumbler about a year after the first incident because something jammed up and the key wouldn’t turn without a lot of fussing. I realize that isn’t the actual switch, though. Other than that, I haven’t done anything related to this issue - nor have I had this issue in the past 2 years, 9 months, 21 days...

[trbankii]

Well, I pulled out the <extensive obscene profanity omitted> ignition switch. It is worn, but does not seem to be bad. I pulled it apart and the contacts aren’t burnt or anything. I went and got a new one because for all of the <more extensive obscene profanity omitted> work to get the switch out of there I figured I’d put a new switch in there to make sure I didn’t have future problems with it.

So, out to try to wrestle the new ignition switch into it...

[More Power]

On a 93, you could carry a length of automotive wire (with a pre-installed spade terminal and battery clip) to jump the shut-off solenoid to a battery if this happens again.

Sounds like an ignition switch to me though...

[trbankii]

Ok, I got the ignition switch back in with a suitable amount of fussing and fuming.

That wasn’t it… Turned the key and still absolutely nothing. But the key clicks from position to position a lot more cleanly. After pulling the <extensive obscene profanity omitted> switch out of there, it was worth the $20 to put a new one in rather than find I had to do that again any time soon.

So I buttoned everything else back up and turned my attention under the hood. DmaxMaverick had originally said that fusible links are the other likely suspect - "suspect circuit is the secondary chassis power, which should run from the starter lug up to the firewall.”

Starting to look at the passenger side area from starter to firewall, I was looking at the available wiring:

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=2998&stc=1&d=1430250966

There’s the big loom coming up and then going back down - with a bunch of wiring sprouting out of it at the apex. Sources tell me the item in the green box is the fuel pump relay and the item in the yellow box is the fuse for the fuel pump. I opened both of those up. The relay is sealed, but I made sure that the connection was well seated. The fuse was fine.

I’m assuming that the collection of white “tubes” that the purple arrow is pointing at are the fusible links? One of them has the wire taped both at the fusible link end and at the end connected to the junction block (by the previous owner). I inspected things and didn’t see anything burnt or blown - but I pushed and prodded at things to make sure it was all connected.

Tried the key and everything lit up. Turned it further and started it right up.

From my second post, I fussed around with the stuff over in that area and checked the fuses right before it started up. So I’m guessing that it is something over there - likely that wire with the tape on it, although the one right under it is connected to a big thick red wire which seems to say “carries all the power for everything” than the littler brown one with the tape.

So… First question - are those “tubes” the fusible links? I’m used to this style:
http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=2999&stc=1&d=1430252033

Or a bunch of them in a holder like this:
http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=3000&stc=1&d=1430252033

I’m having trouble tracking down anything that looks like what is in the truck. What should I be looking for?

Second question - is there anything else I’ve misidentified in the first photo? Or should I be looking for fusible links elsewhere?

[trbankii]

On a 93, you could carry a length of automotive wire (with a pre-installed spade terminal and battery clip) to jump the shut-off solenoid to a battery if this happens again.

Is the shut-off solenoid the item in the green box? Others referred to it as the fuel pump relay, but I could see that being the same thing.

I went back out and was able to get the motor to stumble while running if I messed around with the wire with the tape on it. I couldn’t completely kill things, but that seems to be the culprit as messing with other things didn’t seem to have any effect.

If that is the culprit, I’m amazed that this has only happened twice in nearly three years.

[DmaxMaverick]

Those are "automotive" fusible links. They will usually discolor and/or blister when they burn. Also note, harnessed resistors will look similar, and are usually white, but they should be marked. The others you pictured are more of an "industry standard" type, but can be used to replace what is in the vehicle, if necessary. The inline "tubes" are preferred for automotive because they aren't exposed (sealed from elements and contact) and are easier to harness. I usually just use inline Maxi fuse holders to replace bad links.

[trbankii]

Ok, playing around with the wire with the tape on it I’ve been able to get the truck to stumble pretty much on command and have got it to shut down completely a couple times.

Curiously, I have not be able to recreate the “full blackout” that I experienced this morning and (nearly) three years ago. I can get it to die completely, but then the power comes back on. So it appears to be some unique position that the wire gets into that doesn’t make contact and my “fussing around” breaks the contact, but then allows it to return to a position that does make contact.

The “tube” in question has a “16” stamped into one end and either “812” or “B12” on the back of it. Others have 12, 16, and 18 stamped on the ends, but with them all together it is hard to see the backs of them.

Obviously, something happened to this one at some time that ended up with it being taped back together. I’m guessing that these aren’t normally replaced just due to my inability to find anything about them.

If it is a fusible link, how do I determine what amperage to replace it with? Amperages of 12, 16, or 18 don’t really make sense. Or could it be a harnessed resistor? As you say, it is fully sealed, so I’d have to cut it open to determine what is actually inside.

[DmaxMaverick]

It's entirely possible it was taped to "help" it maintain contact. I'm guilty of doing this, but only as a temporary solution.

The reference number is more likely the wire gage. I've replaced them according to the diagram spec, or the wire gage, and never really paid attention to their markings. I don't have a 93 diagram, so I can't say what it should be. Ideally, the fuse/link should be just shy of the smallest wire gage in the entire circuit (the "weak" link), or between the maximum component amperage and the maximum the wire will support, including the ground source (automotive wiring is almost always too close for my comfort).

For testing purposes, you can use a CB. I recommend a manual reset. This will allow you to determine if the problem is a weak link, or an overloading circuit (for whatever reason). I do not recommend using a CB as a permanent solution, as 12V CB's are generally unreliable for continuous duty.

[Dvldog8793]

Howdy
If you replace a Fusible link with an inline, I would use a slow blow fuse. A fusible link does not act the same as a fuse and sometimes if you use a regular Maxi you will either blow lots of fuses or if you get one that does not blow regularly then you might not have sufficient protection. The Fusible links are available at most parts stores and the value can be found in the schematic. Make sure you either solder the connections and use heat shrink or do a REAL good job with the HEAT SEAL butt connectors.

Might not be bad idea to trace that wire back and see if there is a problem someplace else. I would think some one was messing with for a reason before.

Good Luck!!!

[trbankii]

Pulling the tape away a bit, I’m seeing bare wires at each end. No idea what the PO was doing here - may have just somehow caught the wire and pulled it loose and then taped it up when he couldn’t readily find a replacement.

I’ll dig through the wiring diagrams to see if I can figure out what to replace it with. I’ll let you know what I find out.

[strykerAKAmack]

Seems more than likely that a wire has failed inside of its outer covering So that from the outside it looks fine but inside the strands have broken ,so it's held together by sheer luck and sometimes will separate just enough to fail occasionally , had that happen to an oil pressure light on a motorcycle years ago , if the ground wire was lost light would turn on . Drove me nuts trying to figure out what the problem was , ended up using a continuity tester on the wires and sure enough outside looked fine but wiggle it in certain way and poof no continuity .
So check the whole length of the wires not just the fuse

[More Power]

The electric fuel lift pump is powered through the oil pressure switch with the engine running and a relay while cranking the engine.

The fuel shut-off solenoid is located inside the top cover of the fuel injection pump. The wire that powers that solenoid was originally pink when the truck left the factory, but turns sorta light brown with time.

On top of the fuel injection pump, there are two electrical connections - a green wire and a larger "pink" wire mentioned earlier. The green is used for the housing pressure cold advance, and is not necessary on an already warm engine.

[trbankii]

Seems more than likely that a wire has failed inside of its outer covering So that from the outside it looks fine but inside the strands have broken ,so it's held together by sheer luck and sometimes will separate just enough to fail occasionally

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=2998&d=1430250965


Pulling the tape away a bit, I’m seeing bare wires at each end. No idea what the PO was doing here - may have just somehow caught the wire and pulled it loose and then taped it up when he couldn’t readily find a replacement.

As noted, this wire has obvious issues - tape mentioned is at red arrows in photo. You can see at the lower arrow that the wire takes nearly a 90 degree bend where it enters the fusible link.

[trbankii]

The electric fuel lift pump is powered through the oil pressure switch with the engine running and a relay while cranking the engine.

I don’t think my issues have anything to do with the lift pump.

When I mess around with the taped wire in the photo above - particularly the end that goes into the fusible link - I can get the engine to stumble or die. When it dies, all the power is going out. Have to dig through the wiring diagrams to see what that particular wire is for, but it seems to be pretty essential. :o

[twaddle]

Tribankii, How did you get on with the blowing fuse a while back on your truck as per this thread? I am having very similar problems with a 1996 6.5 Suburban. Any help would be much appreciated. Jim T

[trbankii]

Well, as detailed in the final few posts, it turned out to be a compromised wire. The wire had been taped up to “help” it out and some new tape has had it running trouble free ever since. See post #22 for most of the details.

[twaddle]

Thanks for taking the time to answer. Mine is the later 96 model and today I couldn't get it to blow the fuse and stall at all. Just thought I'd ask you in case there has been some more fun since your last post. Jim T

[trbankii]

Sounds like you’re dealing with a different issue, but with these decades old rigs going over the wiring for anything funky is a good starting point.