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'91 ecu troubles
#30
cab temps in cars can hit 200F easy parked in the sun,, windows up. this proves deadly to many parts in ECU.. (all our ECUs here die from that heat, every one)
and water, sure, that too, is bad. (we lost ECU here for simple window (windshield) cracks. the potting also protects from vibration damage (3 way protection)

signals. (inputted?) (you can't use a test lamp to measure TTL signals. you do know that ,right"?) or what ever it is.. 74HC173? (guessing at '1')? 8bit latch?
https://en.wikipedia.org/wiki/Transistor...stor_logic
we don't know any of this yet, we don't t even know what processor that is. (it too is a contract part, see the number? see that "S" prefix?)
does that other chip the 173 driver to the main driver, called a pre-driver? connect up?


http://www.st.com/web/en/catalog/sense_p...pe=keyword

they make processors in different voltage classes now. lower (VDD), is faster and less heat.
but if the uP is 5vdc then the signals will be that, 0 to 5v, or TTL highs and lows. TTL is about (ViL) 0-0.8 and when high 2v to 4 v (Vih).
see page 18 here for all families
http://www.slideshare.net/aMiERuLz/logic-families-1

that driver probably is a near discrete component (modern type) the newer parts have current limiters inside, thermal overload protection, and that coil of yours has huge back EFI spicks (read damaging) to deal with, so will have a back EMP clamp.

in the olden days, all those parts were on the outside (not seen on yours), so ST.com made a new part that does all that magic in one part.
i put the link to the typical ST.com part used for ECU.'s
Other drivers( well which one? there are many VSV and solenoids, and ISC motors used)
the other drivers, are usually in a special form or chip or SIP , and many today are obsolete.. do no assume anything, get the data sheet and read it.
only that works.
and what if the ECU cut spark on purpose? (didn't like the timing relation ship, cam to crank,) what if? be sad to learn that after a new ECU installed.
happens like 90% on the forums... that, (the poster not understanding the ECU logic rules on spark, some ECu are very strict here)


here is one part (coil driver, common)
http://www.st.com/web/en/catalog/sense_p...pe=keyword

HVc is the coil pin. note the complex paths.!
the modern coil is a nasty beast.
my scope views showed that, it can blow up most simple discrete transistors fast. with that huge spike and currents.
VB526SP-E (search for that part , as 1 example)
this part (not saying it's yours) is classic part here. in many millions of cars.

the input has a pull down, so the device does not go active, if the input is disconnected and burn up the cars coil.
page3 in the data sheet shows the input requirement and the schmitt trigger thresholds. 0.4v.
Vil 0.3 to Vih 4v. for this part . using 5v. this device trips with input 1.9v or less.
but as stated above, the signal will be fast.
page 13 in the data sheet PDF shows the uP to driver connections.
this part is a 125watt part. (limited by junction temps inside)

your driver is not a simple transistor. unless there is 2 in one package. but did you trace all 6 wires there? do 2 pins go to the main connector
some ECU can to 4 and 6 cylinders, with one ECU, (a prime goal today) and more. (eg, one ecu fits many engine, and has flash uploads)
but again, we dont have the data sheet, above is me pretending we did.... as an example

if the driver is say a 6 pin dual channel twin transistor. see those 3 pin pairs. what if? and then it has external clamp diodes and its bad, the new part will fail pronto.
i see SIP packs right next to the driver chips, are they related? are they custom clamps for the driver? who knows?, lacking a full trace out....
the other connections can be in the center layers of the card,,, making all this hard to discover. lacking xray machine.

Finding and buying old parts, can be very hard, (dispite the cloner sellers claims)
most parts are out of production, those parts were made 20 years ago, and the technology moved on,,,, today we expect the devices not to blow up
when a simple spark coil shorts. back in 1996 , they did go boom on most cars , back then.
but not all, did that. Maybe Siemens is more advanced, then... I dont know. until the data sheets arrive.


lets now talk Dwell: (rule one, infinite dwell burns up all coils)
the coil dwell time , is about 15mS max, this is long to reach saturation of the coil (- lug) (the coil maker dictates this, and if exceeded it burns up)
15 Milli seconds. 15/1000th of a Second.
on modern cars, it varies, from cranking to max RPM, to keep heat down and to make dwell longer at high rpm. not over 15mS,
so the coil pin is at 12vdc when the coil is off, a test light glows then.
then the ECU charges the coil for say 10mS, you cant see that with out a scope.
if you crank it the light may, flicker,? this dont prove it's working, not at all. or with normal eyes, you might see nothing..
math:
your engine turns 250rpm cranked. divide by 60 to get seconds. (wasted spark rules)
so is 4.1 RPS revs per sec. call it 4. and coil 1/4 fires together, 2 times, per 4 sec. (a wasted spark deal) 1,3,4,2 order but fires 1/4, the 2/3, then 1/4 again, in one turn of crankshaft.

250 ms per turn (=4PRS). during that 250MS period the coil is charged 2 times, at 10mS each turn. (typical)
that works out to 12v for 230ms and 2 negative pulses for 10mS each. FAST that is, 10/1000th second.... fast..
most humans can not see light flash that fast. (why movies are called flicks) Movies are best seen at 20 frames a sec. or faster for comfort.
some can , some cant see the flick. one person see a movie the other sees torture. (1920 Charley Chapman era, seen today at excess speeds.)

the scope cures this. we can see 3 things, the full pulse, any noise there, and the fact that the pulse is NOT WEAK.
The WEAK thing, only scopes can see. never some test light.
the scope will allow me to see a leaking transistor, say causes the voltage not to reach full battery volts. 0v, 10v, 0v 10v. like that. and would be bad.
it's an analog world, to a tech. and is not digital , until digitized.
or the low signal does not reach 0v. that too is bad driver.


substitutes, why are you doing that, and the part is still unknown
you cant do that, yet.
what if the part has read back pin.?
if you dont get that right, the ECU will shut down the coil.

Good luck finding out what contract parts are used.... that be super good to know,
most companies, have a non disclosure agreements, with contracts, and ST.com is bound by that .... a signed contract.
them might even say, we are not going to read ours, just for you.
in most cases, they tell me that, it's a contract and that is all we are saying,,,,
that is why I send my hard nut cases to CARDone.
they dod all this hard work for me.....
but yes, after full rev. engineering i can replace a dead obsolete, VSV solenoid driver, in a SIP pack, i cut the pins off the dead transistor
and add my one, discrete trans. but its just a SIP pack with 6 transistors, NPN and i know the beta and other specs. too. so can sub out easy
but as i say, you dont even know what you have. yet.



Cardone may say, sorry, can't do Siemens anything....



2 wire CKP sensors only, (is yours 2 wire?)
https://www.youtube.com/watch?v=2tHkV3v6XIo
see the first seconds here, of the VR CKP? first 3 seconds of video, repeat this... over and over. see?
see how weak it is. then it starts, and voltage just to +2 volts and -2v swings... (faster you go the more volts it does)
so.... that is how we check CKP
there is NO other ways.
sorry. and is 1st check. when spark is lost.

here is same deal, but note its only 0.2v up and down. weak as a cat.
see? great example of weak CKP, yours is new, and im sure strong. but is the timing right, does it match the cam? !
https://www.youtube.com/watch?v=7Ofa8Gcn7S8

see coil as amps. , see each charge up.
here
https://www.youtube.com/watch?v=F8Pr81mH...c7fHhuPJIV
http://www.fixkick.com
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Messages In This Thread
'91 ecu troubles - by Kirk - 06-05-2015, 04:55 PM
RE: '91 ecu troubles - by fixkick - 06-05-2015, 11:05 PM
RE: '91 ecu troubles - by Kirk - 06-08-2015, 04:28 AM
RE: '91 ecu troubles - by GeoHacker - 06-06-2015, 02:41 PM
RE: '91 ecu troubles - by fixkick - 06-06-2015, 11:17 PM
RE: '91 ecu troubles - by GeoHacker - 06-08-2015, 07:23 AM
RE: '91 ecu troubles - by fixkick - 06-08-2015, 04:39 AM
RE: '91 ecu troubles - by fixkick - 06-08-2015, 11:16 PM
RE: '91 ecu troubles - by greenfield54 - 09-26-2015, 09:15 PM
RE: '91 ecu troubles - by fixkick - 09-26-2015, 11:38 PM
RE: '91 ecu troubles - by greenfield54 - 09-27-2015, 08:26 PM
RE: '91 ecu troubles - by greenfield54 - 09-29-2015, 09:41 PM
RE: '91 ecu troubles - by greenfield54 - 10-01-2015, 07:50 PM
RE: '91 ecu troubles - by fixkick - 10-01-2015, 11:55 PM
RE: '91 ecu troubles - by greenfield54 - 10-02-2015, 09:40 PM
RE: '91 ecu troubles - by greenfield54 - 10-03-2015, 10:11 PM
RE: '91 ecu troubles - by fixkick - 10-03-2015, 10:57 PM
RE: '91 ecu troubles - by greenfield54 - 10-03-2015, 11:03 PM
RE: '91 ecu troubles - by fixkick - 10-03-2015, 11:15 PM
RE: '91 ecu troubles - by greenfield54 - 10-03-2015, 11:21 PM
RE: '91 ecu troubles - by fixkick - 10-03-2015, 11:36 PM
RE: '91 ecu troubles - by greenfield54 - 10-03-2015, 11:47 PM
RE: '91 ecu troubles - by fixkick - 10-03-2015, 11:54 PM
RE: '91 ecu troubles - by greenfield54 - 10-04-2015, 08:56 PM
RE: '91 ecu troubles - by fixkick - 10-04-2015, 11:42 PM
RE: '91 ecu troubles - by fixkick - 10-05-2015, 02:15 AM
RE: '91 ecu troubles - by greenfield54 - 10-05-2015, 09:42 PM
RE: '91 ecu troubles - by fixkick - 10-05-2015, 10:43 PM
RE: '91 ecu troubles - by greenfield54 - 10-06-2015, 09:01 PM
RE: '91 ecu troubles - by fixkick - 10-06-2015, 11:00 PM
RE: '91 ecu troubles - by greenfield54 - 10-07-2015, 06:41 PM
RE: '91 ecu troubles - by fixkick - 10-07-2015, 10:07 PM
RE: '91 ecu troubles - by fixkick - 10-07-2015, 11:11 PM
RE: '91 ecu troubles - by greenfield54 - 10-09-2015, 09:32 PM
RE: '91 ecu troubles - by fixkick - 10-09-2015, 10:04 PM
RE: '91 ecu troubles - by greenfield54 - 10-09-2015, 10:23 PM
RE: '91 ecu troubles - by fixkick - 10-09-2015, 11:19 PM
RE: '91 ecu troubles - by fixkick - 10-10-2015, 12:36 AM
RE: '91 ecu troubles - by greenfield54 - 10-10-2015, 01:10 PM
RE: '91 ecu troubles - by fixkick - 10-10-2015, 10:35 PM
RE: '91 ecu troubles - by greenfield54 - 10-16-2015, 09:08 PM
RE: '91 ecu troubles - by fixkick - 10-22-2015, 03:56 AM
RE: '91 ecu troubles - by greenfield54 - 10-22-2015, 09:20 PM
RE: '91 ecu troubles - by fixkick - 10-23-2015, 01:25 AM
RE: '91 ecu troubles - by greenfield54 - 10-24-2015, 09:03 PM
RE: '91 ecu troubles - by fixkick - 10-25-2015, 04:12 AM
RE: '91 ecu troubles - by greenfield54 - 10-26-2015, 09:16 PM
RE: '91 ecu troubles - by fixkick - 10-26-2015, 10:41 PM
RE: '91 ecu troubles - by greenfield54 - 10-27-2015, 09:29 PM
RE: '91 ecu troubles - by fixkick - 10-27-2015, 11:04 PM

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