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Today I only did a just little investigating of my strange TT igniter / bad IGF issue. More tomorrow.
--Tested continuity between TT igniter harness connector "A" Pin 4 (Ground) to the intake manifold and got a good signal.
--Tested continuity between the TT Noise Filter connector Pin 2 (Ground) to the intake manifold and got a good signal.
--Tested continuity between the TT igniter harness "A" connector Pin 4 (Ground) and the EB1-7 Ground JUST because I was curious... and got continuity there too. Common ground circuit I guess?
So I think the ground is okay but I'll still look into it further.
In past months I did extensive continuity testing and repair of the coil pack connector wires and pins a while back and made sure they're all good to the ECU. I'll have to double check all my previous investigative notes there in previous pages of this thread. Tomorrow I'll try running the spare TT USDM OBD1 6-speed ECU that I have.
Also will run the voltage drop test across all the coils to rule out any irregularities.
While searching I did find this interesting thread that sounds like a somewhat similar issue. The OP went to ridiculous lengths to find the culprit but to no avail: https://www.supraforums.com/forum/sh...-error-code-14
Then I found some interesting info to learn from from this thread (involving MKIII Supras but the theory of how Toyota IGT and IGF signals work seems to be the same): http://www.supramania.com/forum/thre...-signal.75628/
Originally Posted by annoyingrob
"There are two signals, IGF and IGT. IGT is the ECU telling the ignitor to fire, IGF is the ignitor telling the ECU that it fired."
"Is the ECM supposed to supply the IGF wire w/ a full time voltage and look for a ground interruption when it gets fire?"
Originally Posted by Travis89Turbo
"No, based off of my research it is normal to see 5v output from the ecu to igniter. But the igniter internally varies the resistance that the ecu translate into confirmation that the spark that it sent a signal out of the IGT actually occurred. The only way to verify this is with a o-scope. Which basically shows a graph of the voltage variance! There is not a DMM on the market anywhere near fast enough to pick up the crazy small voltage variance!"
So this suggests a reason why realistically the only way we can test whether or not an igniter is good or bad is to just install a known good igniter for sake of comparison...?
Also this is interesting diagnostic theory I'm trying to learn from. It's diagnosis is for a 1991 LS400 with dual igniters and distributors but the theory appears to be the same for any Toyota/Lexus engine of the era.
Connect the other ecu with the old igniter (which you got the car last running) and see what it does.
There is not much to fail on one side of the igniter since they are coils. Whereas the other side is all controlled by the ECU assuming harness is good.
The exercise will at least isolate the ECU if it is the one causing you trouble.
That was my thought too— keep the 1996 era igniter installed when trying the spare TT ECU. Then see what happens.
The plot thickens though... I noticed over the last few weeks some residue on the plastic fuse box cover and just assumed this was leftover from the power steering system leaks I had been encountering a while back. I wiped it all off thoroughly but it continued to show up. But it wasn’t PS fluid really.
Then more recently I began to notice the Bosch 24F battery was leaking some fluid from its vent caps and from the battery terminals themselves. It struck me as odd but I cleaned it up and kept driving... until igniter #3 failed.
Last night while researching all of this I realized that could be a sign that the battery is failing due to overcharging from a bad voltage regulator on the alternator.
And I have noticed some slight fluctuation on my analog voltmeter gauge. Nothing major but the voltage always wavered a bit ever so slightly. I never saw it read above 14V (whenever I *did* look at it) so I thought nothing of it.
With all this in mind and knowing my TT 90-amp alterntor is original and never rebuilt from the 90’s with 67k miles on it (supposedly) from the time I installed it, I have ordered a new TT Auto 100-amp reman from McGeorge Toyota.
I’ll install that when it comes in and get the core fee back.
It will at the very least elmininate a longstanding concern I’ve had over whether an alternator that old is really OK.
First thing today is to go and buy a new 24F battery to replace my 3+ year old leaking Bosch. I’m going with an Interstate, AC Delco or Die Hard.
Run a ground wire from the intake ground point to the battery negative or the chassis ground on the frame rail, or straight from the ignitor to the battery negative as a test. I suspect that intake ground is having some interference as it's not the most foolproof. The old single coil ignitors used induction for the igf, think wireless charging where the coil firing induces current in the return path.. but the newer multi coil ignitors I want to say switched to a logic circuit in the ignitor, so they do need a good ground. Toyota ignitors don't fail that often, you probably have something else going on but try that first. A continuity test might pass, but that doesn't mean it can support the amps when running.. electrons flow from ground to positive as backwards as it sounds so def eliminate that first.
Other than that... I know 2 people that did not have the igf pin fully seated in the ecu connector, or the lock tab on that pin was broken, so if you wiggle the ecu plug and it starts running youll know right away that's the issue.
Sadly I’ve still had no time to diagnose my igniter issue with all the holiday stuff going on. Enough time to do something quick and cursory yes but not to really investigate.
Tonight I got a new Interstate 24F MTP battery installed to replace the old leaking Bosch battery.
Also the brand new TT igniter (now my fourth) came in this afternoon. However I am reluctant to install it in the car yet if I feel I haven't found the root of the issue. Maybe I don't have a choice if all three previous igniters really are internally damaged/fried.
I’m still waiting on the Toyota reman TT Automatic 100-Amp alternator to come in to replace my old 1990's original used TT 6-speed 90-Amp alt with supposedly 67k miles on it plus my roughly 1,000+ miles of added use (the seller said it was "67k miles" but how do I know?) and a suspected failing voltage regulator.
A couple of things occurred to me when double checking my manifold and block grounds for both continuity and for any irregularities (I found none):
In this shot below you can see the TT igniter currently installed (the 1996 era unit with the old style mounting bracket which has failed on me several times). There are some non-stock extra harness wires that go into a multi wire Weather Pack heavy duty connector just above and to the left of the igniter. Those carry various 12V functions: my fog lamp on/off switch wiring, oil pressure gauge sender wire, A/C aux cooling fan override wire and something else I am forgetting offhand right now).
Now I made these connections a bit shorter than they should be for neatness so I do need to go back and extend them and clean them up later to make it look tidy. Not important right now. Just noting.
Then to the RIGHT of the TT igniter is a big thick plastic conduit section that pushes right up against the igniter. Inside this is my 10 Gauge direct battery feed wire that goes right to the relay for my TT Denso fuel pump. I am wondering if there is any way... at all... due to that wire carrying up to 20A or so for the fuel pump.... that some kind of electromagnetic field could be generated from it and thus somehow affect the TT igniter pressed right up against it?
My assumption is that there is absolutely no way this would be so and that this is just ridiculous thinking on my part. Nonetheless I thought I'd bring it up just on the 0.01% chance I'm not asking something completely absurd.
Next, I want to replace these fuses (or are they "fusible links"?) in my main under hood fuse box.
There is clearly visible corrosion on inside of the AM1 and ALT fuses (the blue and white ones below). Moreover they proved to be impossible to attempt to remove without destroying them in the process. So I let off and am looking for the part numbers for these (specific to the SC300's original electrical system) but so far I am finding nothing.
Run a ground wire from the intake ground point to the battery negative or the chassis ground on the frame rail, or straight from the ignitor to the battery negative as a test. I suspect that intake ground is having some interference as it's not the most foolproof. The old single coil ignitors used induction for the igf, think wireless charging where the coil firing induces current in the return path.. but the newer multi coil ignitors I want to say switched to a logic circuit in the ignitor, so they do need a good ground. Toyota ignitors don't fail that often, you probably have something else going on but try that first. A continuity test might pass, but that doesn't mean it can support the amps when running.. electrons flow from ground to positive as backwards as it sounds so def eliminate that first.
Other than that... I know 2 people that did not have the igf pin fully seated in the ecu connector, or the lock tab on that pin was broken, so if you wiggle the ecu plug and it starts running youll know right away that's the issue.
Thanks Ali. I have enough spare wire in thick gauge that I can make myself a secondary ground from the intake manifold direct to the neg battery terminal or chassis ground point. I think I also need to see a picture of both 2JZGTE intake manifold gound wires from a harness onto the manifold. Right now I can only easily find one of them but I know I looked over all the connections carefully when I installed the harness with the engine on the stand. Hopefully I didn't do something wrong there.
When you describe the two types of coil systems I think you're referring to the distributor with single coil setup that the 2JZ-GE non-vvt-i has versus the 2JZGTE's multi-coil system?
From what you've said I am gathering that the coil system I am dealing with has a logic circuit within the TT igniter itself which is what communicates the IGT and IGF signals between itself and the engine ECU. Which is why good grounds are VERY important. It is that correct?
Right now I have only three hunches. Maybe even one of them holds merit:
A) I have a bad or poor ground that is affecting the ignitor and not allowing current to flow correctly
B) A longshot... but my strong indication of a failing alternator voltage regulator having caused a battery overcharge situation and eventual battery leakage/seepage may have also affected other things electrically. Doubtful but I am addressing this anyway as a separate issue
C) There actually is an issue with the ECU not accepting or possibly in some way frying the IGF generating circuit inside all these TT ignitors. No idea on that one way or the other but I didn't think that would be possible anyway since the IGF signal is received by the main ECU, not sent.
What makes me think it probably isn't the main TT ECU being at fault is that every time I have installed a known good or brand new TT ignitor... the problem mysteriously goes away for a couple of weeks or more. Until it returns in the same way: rapid deterioration of the ignitor's IGF signal until it doesn't start the car any longer at all.
I feel like it's got to have something to do with either too much voltage/amperage going into the ignitor somehow (but how would that even be??) or a bad ground issue not allowing enough current to flow out of the ignitor's critical brain circuitry.... which eventually causes a burnout to occur.
So maybe the only surefire way to test that theory is to make a direct wire ground to the negative battery terminal or direct to the intake manifold...?
The current tally when I'm able to properly investigate this issue soon the tally of things to check is now:
--I'll replace the alternator with the new reman. Since I suspect the voltage regulator in my old used alternator I want to rule this out. Probably unrelated but I also just spend $150 on a new battery so I don't want to overcharge that as well.
--Since they look corroded inside I will try to replace the original SC300 AM1 100A and ALT 120A fuses. Probably unrelated but... it seems reasonable if I have observed corrosion in each?
--swap out the current TT 6-speed ECU (which has been capacitor serviced by Driftmotion) and install my spare TT 6-speed ECU (not yet capacitor serviced) and see if it makes any difference
--voltage drop test across all coils and the igniter
--make absolutely sure my front intake manifold ground off the harness is in the right place
--run a new ground wire (12ga? 10ga?) from the intake manifold to the negative terminal or chassis ground on the frame rail
--as a test, run a ground wire direct from the ignitor to the battery negative terminal
--recheck my IGF pin at the TT ignitor and on the ECU connector
edit: adding this simple video which explains how to perform a voltage drop test on any circuit. It’s basically testing each section to see if any junction point in a circuit takes the path of least reaistance (ie: your multimeter) out of the acceptable range specified in the TSRM due to a short of some kind.
I’m still waiting on the new alternator to come in but in the meantime, this showed up
A new(er) LH driver’s side headlight from a 2000 SC400.
I’ll look for a spare passenger side headlight assembly later. The long term objective is to take my old ones out and have OG Status restore and upgrade them.
This is a huge improvement over the severely yellowed, fogged and internal moisture-leak affected ‘93 original driver’s headlight.
With the swap mostly completed I’m focusing bit by bit again on the cosmetic restoration.
Craig!!!! I've been away from the forums for a while. Hope all is going well with you. Glad to read you got it started and are diligently working through everything.
Craig!!!! I've been away from the forums for a while. Hope all is going well with you. Glad to read you got it started and are diligently working through everything.
Jim
Hey Jim!! Hope you’ve been doing well! How is it going with your SC?
Things are going well on my end. Just getting busy again as we’re well into the new year.
Yes, I got the car through the break-in and well past. And other than an underrated slipping clutch (which I will address soon) it drives brilliantly! It’s all I wanted and I love what its turned into now.
I had a setback in late December unfortunately— the car keeps blowing igniters within a 1-3 week span for some reason.
I haven’t driven it for nearly a month while trying to sort out the issues. Gerry has been very kind to help me troubleshoot but we still don’t know for sure. The holidays kind of took over so I have only just begun to investigate.
Easiest case I may just need new coil packs. Worst case I need to pull out the wiring harness and verify all the ignition wires and basically the entire harness.... or send my untouched stock 5-speed CA harness to Tweak’d and get a new harness made. But we’ll see. Still more investigating to do before I commit to that or putting my current swap harness on the work table to tear apart.
I have suspected that issues developed because of my old alternator causing overcharging so I replaced that with a new 100A TT Auto Toyota reman and got a new battery... but the issue seems to still be there even when I tried a good used igniter from Gerry AND a brand new igniter from Toyota.
Tonight I removed all the 1k+ mile new Denso OEM-spec (but not from a Toyota dealer, so the Toyota logo and P/N is not embossed) GTE ignition coils and replaced them with a really old very used and untested OEM Toyota coil pack set I had in a box (which do have the Toyota logo and P/N embossed).
First start attempt with the good/tested/verified/working igniter that Gerrb just sold me and it was a no go... but the engine WANTED to start.
I then swapped in the brand new OEM igniter that I just bought from Driftmotion which was only used once the other day.
It started up right away. Twice. The second time it was a little delayed/weak at first but it was fine after that, if ever so slightly not glass smooth at idle. These were really old used Toyota coils with unknown history. One of those really old coils has a broken clip tab for the coil connector so I had to tension tape it in place with some electrical tape to make sure the connector stayed put. This was all done for testing purposes after all.
Gerry, I know you would probably not have advised this but I did run the engine for a couple of minutes. Really just to observe the idle and see if there was any breakup or Code 14 when I raised the RPMs. Neither happened.
Also now (with the new alternator installed) instead of gently fluctuating voltage readings from my analog VDO gauge I am getting a consistent and steady 14V.
So I seem to be back where I started again: any time I install a *brand new* igniter... the car is fine. And this is the case now unless this new igniter also suffers a burnout. I'm still investigating.
But as of right now this is what has changed from before:
--new re-manufactured TT Auto 100A alternator bought from Toyota (replaced the old 90's era original 68k mile 90A TT 6-speed alternator which I suspect had a failing voltage regulator)
--new Interstate battery (replaced my 3+ year old Bosch battery that I observed to be leaking for many weeks before I realized that was probably a bad sign)
--removed Denso OEM-spec ignition coils that were bought new and replaced them with old used Toyota ignition coils
If it is possible that the Denso coils or one or two of them are defective or damaged causing igniter issues then I'll replace them... but this time with the Toyota versions. And a new set of Denso 5304 IK20 plugs for good measure.
Testing so far has not suggested to me that this is an ECU issue. It could still well be a wiring issue. But... at least some parameters have changed that MIGHT have affected the coils or igniter.
Craig - now for two or three times in a row , remove igniter and ecu .... jostling the wires on the connectors , reinstall them and try re-starting so we can confirm if it is a wire / pin within those connectors causing you problem. Remember , the other day you replaced those two items and when you reinstalled that same igniter and ecu , it wouldn't start . Now the only thing that changed were the coils.
Analyzing closely the ignition circuitry after I have asked you to interchange the coils , if truly those coils you removed have shortage on one of the coil's primary winding that causes brand new igniters to burn out left and right , before that happens your 30A fuse would burn out ... but you are not burning any fuse . If a primary winding wiring is open instead of shorted then no current flow thus should not burn your igniters .
We have two separate issues , non starting at times and burning out of igniters . At this point , I will still go back to my original assessment ...wiring issue since the problem is intermittent . But you have to confirm again by removing ecu / igniter and reinstalling a couple of times and jostle their connector wires.
All right. I think it's fair to say that a culprit was found for that latest issue with the burning up of TT igniters (which four of when all was said and done).
Ultimately it was a bad ECU. Thankfully I had found a deal on another USDM 6-speed 2JZGTE OBD1 ECU late last year and tucked it away as a spare. Little did I know that I would need it so soon!
From what I can tell, and Gerry I think you agree with me after our conversations, here is what happened:
I used a 67k mile OLD, old old but said to be "good" OEM original USDM Supra TT 6-speed 90-amp alternator. I never began with a new one, thinking that one would be fine. I slowly figured out that it had a bad voltage regulator during the first 1,000+ miles of running the new engine. A big indicator was I realized the battery had started leaking and would continue to each time I wiped off the residue.
Its voltage output was fluctuating. Sometimes it was a tiny bit low and other times where it should be (or so I thought) but it was almost certainly overcharging the battery and sending a bit too much voltage into the electrical system.
This seemed to affect the speedometer and tach randomly when first starting up.
Meanwhile it was also likely harming my ECU. Or.... possibly my first ECU was just having an issue anyway. Either way the circuits that control the signal TO the igniter and back FROM the igniter (the IGF signal aka any Code 14 CEL if you ever have that issue) were not acting correctly. And this was causing a burning of every igniter I used until they no longer worked. New ones took longer to burn out than old good used ones.
Four things fixed this issue, since I checked my ignition wiring previously and checked my IGF wire many times during this diagnosis:
--Replaced the battery. Due to its age and likely overcharging harming it I figured it was a safe bet to just get a new one.
--Replaced the alternator with a "new" remanufactured 100-amp TT one from Toyota. Now voltage output was solid and constant within spec.
--Replaced my first 2JZGTE ECU with another good one. Identical part number. I still haven't had it capacitor repaired but I'm in no hurry for that now.
--Replaced my last burned igniter with yet another new one from Driftmotion.
I considered replacing all the coil packs with new ones but after testing with some really old spare TT coil packs it was determined that they are not the issue.
At this point the car:
--Starts normally
--Idles smoothly
--Drives normally
--Has normal speedo function requiring no slapping on the dash to make it activate
--Has normal immediate tach function with no initial delay before the needle starts showing rpm
--has a very stable and unwavering voltage reading on my voltmeter gauge... unlike what I observed with the old alternator
If I'm wrong I will know soon enough. I also bought *another* brand new spare igniter that I am keeping in the trunk for an emergency but with the entire ignition and charging system having been gone through including finally replacing the ECU there is nothing else that could affect burning igniters so quickly. My wiring could have an issue but I doubt that now.
So for anyone who has chased a strange issue with igniters being burned, always check your wiring (especially if it's a custom wiring harness) but also make sure your alternator and its voltage regulator is in good working condition. Have it tested to be sure. And make sure your ECU is not the culprit. Also make sure a bad alternator did not harm your ECU
...
So with that out of the way, I'm back to:
--get OEM antenna to work with manual up/down switch function and not shut off the amplifier when it's put down (making a couple of patch harnesses following Raine's thread for this)
--find the correct Y adapter to be able to plug in both the main antenna and the rear windscreen antenna into my aftermarket stereo to get diversity tuning to work again. Unless that's something only the original stereo head unit could do.
--replace my very old A/C compressor that has a loud and squeaky magnetic clutch with a brand new (not reman) Denso compressor
--get the slipping SB Stage 2 Daily clutch replaced with the SB Stage 3 Daily kit which should solve the power holding issue for good.
--get steering rack bushings replaced again with Figs bushings (the dealer mistakenly threw out my old Diazen bushings with the old rack and didn't install them on my new rack)
--get that TT Auto LSD diff with the custom 4.27 ring and pinion out of the car and get it rebuilt back to the 3.76 ring and pinion and reinstall
Craig - I do believe that the ECU became your problem all along . It may not be that way on the break in period till your 1000th mile ... but after that , it became the problem.
So looks like your engine harness is good after all.
12-26-18, 04:45 PM
. If a primary winding wiring is open instead of shorted then no current flow thus should not burn your igniters .
. It may not be that way on the break in period till your 1000th mile ... but after that , it became the problem.