I.A.C Valve????

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Re: I.A.C Valve????

Postby KimAndersen » Tue Feb 12, 2013 11:16 am

You're onto something right there Fat Freddy - the voltage spikes are very important in detecting an error in the circuit - for example when there is open load in the driver stage or a wiring problem.

These waveforms are taken from a Infineon TLE4729G 2-Phase Stepper-Motor Driver and explains how a open load is detected. So voltage spikes or as Infineon calls them fly-back voltage are important.


Error Detection Method:

If an inductive load is connected, one of the outputs will rise to a voltage VS+VFU (VFU beingthe forward voltage of the source-transistor freewheeling diode). This voltage is detected by a comparator which resets the flip-flop. As this happens much faster than the 15us filtertime, the error flag is not set under normal operation (Figure 3). If, however, the inductive fly-back is missing due to open load and the voltage does not rise above VS, the flip-flop remains set and the error flag 1 is set after 15us (Figure 4, Figure 5).

Normal_Fig3.jpg


Open_Load_Error_Fig4.jpg



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Re: I.A.C Valve????

Postby ecosse » Tue Feb 12, 2013 7:30 pm

Hi guys been looking at this today, my thought was the pcm was at fault, and as (scanner danner said) when component disconected ive only got, 3 signals yet when conected its got four, my thoughts were that the 4th signal picked up whilst component plugged in was a ghost signal from one of the other channels, so when i read this here i thought about it and so my conclusion is, other mechanic who looked at it has fried its drivers some how, or the old component, or the new cheap and nasty one did.

some great info here, from every one who input's i thank you,and for the help in learning this scope technique.

i am still trying to get it together in my head, that is the captures ive got and interperating them :D

sure it will sink in soon enough :shock:
Attachments
jeep_reconect.jpg
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Re: I.A.C Valve????

Postby ecosse » Tue Feb 12, 2013 7:36 pm

one thing to note is thazt the first captures, they were taken with me just plugging in to any channel, later after some info from autonerdz guys across the pond, i connected as above and i'm sure that the blue channel is indeed the same as the green from before :D next time i will make notes :D

the attached picture a bit crude ,but does show only current flow good on 2 channels only have one clamp so just switched between wires whilst vehicle running :D

ecu deemed broken :shock: i did think this initally when i saw the 3 up 1 down on the capture but what you guys have been saying makes sense and i'm convinced now the ecu drivers are F.U.B.A.R

Thanks guys

these are from the jeep pins 1 and 4 i think :oops:
Attachments
jeep no signal wire.psdata
(127.85 KiB) Downloaded 189 times
jeep wire without signal running engine.psdata
(127.6 KiB) Downloaded 189 times
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Re: I.A.C Valve????

Postby ScannerDanner » Wed Feb 13, 2013 4:11 am

darn. forgot to subscribe to this thread. also Im typing on my phone right now and can't look at the final pics. just thought i would provide more operation of this valve. it has only two internal coils unlike say a Nissan 6 wire stepper that has four coils.
the two coils are controlled by reverse polarity circuits. So for each coil when one side is switched to power the other side is switched to ground and vice versa. So with one driver open on one coil what you were seeing plugged in was the one driver switching high and low and you were seeing this travel through the windings of the coil on the other wire too (the dead wire). the reason the resistance of the coil was a non factor was because there was no current flow. no current flow = no voltage drop.
this is why unplugged we only saw activity on three wires.
also with my case study, yes, the voltage spikes are due to small magnetic field collapses and you cannot have a magnetic field without current flow!
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Re: I.A.C Valve????

Postby Fat Freddy » Thu Feb 14, 2013 7:30 am

Thanks guys. I wasn't too sure if I had it right.

And a nice bit of extra info on error detection there. Thanks Kim


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Re: I.A.C Valve????

Postby ecosse » Thu Feb 14, 2013 10:02 pm

Update on this is i have sent ecu for testing/repair and will post back when i get a min :D

ive been posting on autonerdz feel free too have a look :D http://www.autonerdz.com/cgi/yabb2/YaBB ... 6200/30#30
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Re: I.A.C Valve????

Postby ecosse » Tue Feb 26, 2013 8:08 pm

Hi guys thanks for the help on this one ive learned alot and a bonus is the vehicle is now fixed, unfortuanatly ive no new data to post as ive been off work and customer has picked up car and took it away.

Will be back for mot shortly and will try and get some captures :D

many thanks

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