f1d094
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Everything posted by f1d094
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For future someone who also needs to disassemble their harness connector: MAKE A NOTE: that here are two long plastic retaining comb-clips that hold in ALL of the pins on each side. It doesn't look like it wants to fall out, but it is pretty loose and if it falls out all your unlabeled connectors are coming too Cut the zip tie and remove tape from the harness/connector Remove the small retaining screw located on the end of the connector by the hook/hinge Use a plastic spudger to run around the edges of the rubber gasket inside the connector Slide the cover away from the harness
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Oh? Do you mean above and beyond burning out the internals on the selector and high-beams swtiches? Do you think this is something to be concerned about now that my power draw has been dropped so much? GENIUS. I was literally just now chatting with my wife about how I can either make the female sides more grabby, or the male sides "fatter". Did not think of twisting to accomplish this. I will keep that one in the arsenal, thanks! Now I just need to get the harness connector disassembled and verify root cause. I already have a spare...which might actually be in the car now (ref. prior comment somewhere). I had an unrelated issue several years ago and put in a new one but the old one tested out great. Uncertain which is in the car now. If I remember I'll open the box in my parts bin and see who's hiding in there.
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I'm right there with you. Hence the disassembly of the harness and connector head. I am very very confident at this juncture that it is something in the head itself...so either a damaged connector, or worn out connector, or bad wire-to-connector crimp/solder. It has to be one of these things. There just isn't anythinge else in the car that would be affected by my tapping on the ECU. "When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth."- Sherlock Holmes Wiggling the harness plug didn't do anything, almost certainly because it is so securely held in place to the ECU, and the ECU to the body. Tapping directly on the harness plug however had the most immediate and obvious effects. This is what made me think it was the "choke coils", their proximity to the most delicate "tap point", but that has now been elimiated. This leaves me with a "I'd bet $1000 USD" confidence level on it being something to do with the connector internals...and so I'm going to disassemble it and have a look. Since the pin receivers are where all the action is, I would think they would be the most likely culprit. I've unplugged the ECU only a handful of times in the 25 years I've owned the car...but who knows what the PO may have done. Now I'm all fired up. Maybe I'll do some re-arranging and find time during my evenings this week...
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I'm generally familiar with the brown-out condition the Z's ran under due to an undersized alternator or so it was explained to me when I replaced my headlight switch assembly... I addressed that a couple decades ago by installing a high output one. Also, during the pandemic, one of my projects was to convert the entire car to LEDs (minus the headlights), which dropped about 200W of load off the electrical. The headlights I was planning on doing very soon...but now that is clearly on hold until I have a drivable car again. ;)
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Not 111% certain on root cause yet, but 100% certain it isn't the ECU (cold solder joints or otherwise). The problem was very reproduceable previously by hitting the ECU hard enough at any time, not just when warm. During testing, I BEAT on the ECU with zero effect. What I did not do is whack the actual harness plug as planned, the pins simply were not secure enough. They did not slide out on their own, but any brushing of the wires in-situ would likely have caused them to slide out or lose contact. They were simply not tight at all. If you look in the photos closely you will see I have a rubberized tie-wrap wudged between the dual-bank wires to help them maintain contact. I don't have an official "pin drag" tool, nor do I have any pins that are the precise size of the ECU pins, except on my spare ECU...I tried a bit of googling about Bosch 35pin connectors to no avail but may revisit that. I should note though that the blade connectors I used are definitely thinner than those on the ECU. I had to really really push to get the female ends of the extensions on the ECU vs the harness connectors that could have been pushed in by an ambitious ant. At this point I have removed the 3 miles of electrical tape wrap that was over the rubber harness covering all the way down to the harness head. I did not have enough time to figure out how the harness head disassembles, so if anyone has one laying around and wants to give me some pointers that would be great. I've not had any time to give it a close look yet. The best I found was one for sale on EBay that has some useful photos. I have a large array of spudgers and other disassembly tools, so I'm sure I can get it apart, but it is always nice to have a look at the inside of what you are working on first. Old plastic is old. My biggest concern is that the problem might be an internal break in one of the wires that isn't discernable externally. Hopefully not though, all of the wires under the tape/rubber look like they were installed yesterday; they are that fresh and new. There is even some marking paint on them that is still pliable; mummies were less well preserved before burial. Another concern I have is when I get the casing open that all the individual connectors come flying out, leaving me to do wire-tracing to re-identify their homes. Hopefully they have individualized stays that are still in good shape. I don't know how I will tighten up / micro-crimp the female leads or if I will simply replace them. There isn't a lot of play in the harness so I am loathe to cut them shorter to get new ends on. I don't even know what these types of ends are called or if they even have a special name. I think they are the same as an injector plug and I have several spares of those, so next weekend I'll look into that. The adventure continues...
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RESULT: Loose harness connector(s). Now to figure out how to either tighten/tweak the harness connectors...or replace them 🫤 There is still a mystery (to me, at any rate) on why the engine would sometimes simply shut off like a switch and sometimes stutter-stop, and why sometimes it would re-start immediately and othertimes re-start 10-20 mins later. My hypothesis is that by simply getting in/out of the car while diagnosing I was re-wiggling the loose connector(s) such that they had good-enough connections, and the changing fault symptoms were a result of different pins or a different combo of pins losing contact. The end result is the same: Fix all the connections and do pin-drag tests on all of them to make sure they are sufficiently grabby. Thank you to everyone. I hope it was fun for you too.
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Because the curious mind must KNOW. For me, owning a classic car is really the journey. I get great satisfaction from understanding all the ins-and-outs of...well, anything. If I drive it, fly it, sail it, race it, ride it, eat it, grow it, run it in my house or office, or if it has moving parts or does anything that impacts my life in any meaningful way, I am driven to know how the thing works, and/or how to build/repair/grow/write/create my own. I like making things.
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Many thanks to you both. I love the idea of testing with the lid off, I should have thought of that. Since the refurb unit won't be here until mid-week I think what I will do in the interim is the following: 1) Assuming I have enough connectors in my bins, make 26 individual extensions so I can "plug the harness" without actually attaching it to the ECU 2) Install the ECU sans case, but connected with my 26 little piggies 3) Run the system 4) Thump the free-floating harness plug 5) Wiggle/Tug every individual connection 6) Use a spudger to do delicate tap/wiggle tests on every little thing inside This should be interesting.
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The ignition system is stock other than the wires and plugs. I did replace the coil many years ago, and maybe the ignition module a few years ago. I say "maybe" because I can't remember if I kept the original (which tested out perfectly) or swapped it back in and put the new one back in my parts bin. The problem that go-around was simply the car battery. Fun fact for anyone playing the stay at home version: It is possible for your battery to have plenty of juice to turn over your car and still be low enough on voltage so that your injectors won't fire. That was a fun one to diagnose. I can say for certain that the tach is spinning as normal and at least the tapping is not imaginary. I can make it stumble/stall 100% if I upgrade the tap to a "knock". However, it is entirely possible that more than one thing is going on and the stalling without tapping or opening/closing of the door could be something else entirely. Problem 'B' doesn't care one lick if you are already dealing with Problem 'A'. Alas. It looks like my order finally got out the door but it won't arrive until next week. We'll soon see what the future holds. Now taking bets at Window #3.
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Just a gut feeling, but based on the how-and-where-and-how-hard I tap on the ECU/connector, it seems like there might be a break in one of these coils...I think this only because they can rattle around a tiny bit in their respective tubes and would likely still "settle" with some sort of contact again because of the confines and 45+ years of work-hardening through vibration might do them in. I'll try and have a peek down the tubes with some sort of magification and see what I can. Alternatively, based on your comment about the darlington transistors, is this any sort of failure mode that makes sense for them? Where rattling or knocking with make them fail temporarily? The very temporary nature of the problem is what is most baffling to me.
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Haha. Indeed. This is me, all day every day. No matter which way this goes, I will be using at least one of my ECUs as a learning/traning tool to do a refurb from the ground-up and truly learn every last function, and to really play with tuning. This is why I already had: A spare ECU, a spare AFM, the FSM, the FI Bible, Bosch Fuel Injection & Engine Management, an Ignition 1-2-3 distributor, and an oscilloscope...as well as a host of articles and posts from around the Internet. But I had planned to do this on my own schedule. It seems my Z has other ideas... In related news, last night I discovered that rebuilt ECUs are actually a dime a dozen; I just failed to Internet properly. I've fallen into some sort of pavlovian response mechanism where I assume everything is unobtainium and start scouring ebay and specialty z-parts shops. But if you look at AutoZone, O'Reilly, RockAuto, NapaAuto, etc. a rebuilt unit can be had for as little as $200, or $175 if you are willing to return a core. I've now re-added the standard parts-jobbers for future needs. It looks like they still have some bits and bobs. If it is useless I can return it no problem, so I figured: why not? When it gets here I'll do some compare-and-contrast. More news at six. Film at eleven.
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I'm just learning what's what. I have near-zero electrictronics background but I am handy with a soldering iron and recently bought an oscilloscope to learn on (Tektronix TDS 1012) I can see that the WMIC labled parts are all metalized polymer capacitors and the resistors I recognize are pretty common...but the ICs? Are those the silver 14(?) pin guys with the heat sinks? And what the heck are those copper-coil towers with blue things next to the plug? I need a magnifying glass. I can't read 'em. Nothing looks like a discrete transistor that I recognize, but the round caps on the side say NEC...so I guess that would be those? When I was running the car previously I've grabbed the harness connector and given it a good hearty wiggle with no change but today when I did the second "tap" it was on the plug and not the unit itself, and it went off like a switch. Mostly though, when I tap it with my foot it is on the lower metal bracket. Tomorrow I will be sure to try and move/wiggle each bit of the harness from the connector up on into the dash and see if that makes any changes.
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