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Pics ~ Exposed Optical Sensor Filter Harness 12553327

dazed

dazed

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Ok I had ripped this apart a few months ago (used to be rubber over the PCB),
when i removed it because I thought it was causing some problems. Doesn't look like a ferrite bead... Any thoughts on how to test this to see if its any good?



I'm got some codes (18,35) start popping up more recently, and I read Buddy suggesting that a 5$ ferrite bead would replace this stock filter harness....if that is my problem.

Is there a way to test this (whatever these 2 chips) on the PCB board is....Or should I just get the ferrite bead?

Would the ferrite bead need to be placed only on these 2 wires or would all of them need to be under the bead?
 

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Looks like you have a few frayed/skechy wires there.....Just remove and plug the 2 ends together......Forget the filter harness, many people remove them without any problem afterwards...
 
Matt, Some people have.....mine has been out....but my replacement alternator has been making noise lately and these codes are popping up on me...(could be unrelated)

I get a slight hesitation than SES light comes on or an occasional stall, then SES light (limp mode activated no Cruise control etc...)

So I may need it??
 
yeah Brooklyn....fraid because it was a MF to get that rubber off with a razor blade....just wanted to see what was in it...
 
Not 100% sure...fuel filter clean...LP seems to be working...though I have a new walbro to install...Even pulled the screen off the fitting in the IP to look at the FTB mod. and found very little (albeit some) metal pieces trapped in it....wonder were they came from....hmmm


Its like hit or miss with the codes....sometimes no problem or just a quick one that can be cleared...other times it wont clear and will be long (limp mode) starting....its like hit or miss. I'm gonna be taking the intake off soon so i can really see the wires, and get in there...I will be replacing the fuel lines as well as FTB and Intake mod. Right now my EGR vacuum line is off...but shouldn't be causing this.
 
You can try to put the ferrite core in there and see if that solves the problem.

That is the only way to find out.

If you can get a close up on the IC (Chips) part of the cable, some electronics wiz may be able to identify what it is? There should be some code stamped on top of the Chips. The Chips is probably broken by now with the heat.
 
JMJNet said:
You If you can get a close up on the IC (Chips) part of the cable, some electronics wiz may be able to identify what it is? There should be some code stamped on top of the Chips. The Chips is probably broken by now with the heat.
Click to expand...

Click on the ATTCHED pictures to enlarge....You can see the numbers on them....
 
I originally thought it was just a capacitor in there, but others said it was a ferrite bead. The ferrite bead may accomplish the same thing. If using a snap over ferrite bead it would be easier to get a small one on just those two lines than Like I did and put it over all of them. Otherwise you can measure the capacitance between those lines with a mulitmeter that has that function. Maybe its supposed to be 22-25 microfarads. And put a better capacitor there, one rated at high temps.

The capacitor looks like it goes between the grey 5 volt PCM reference and the white sensor ground back to the PCM. Just to make sure the voltage source is clean. This is a common practice for power sources before integrated circuits.
 
The colors are really faded on those wires...but traced out to the plug....the top left (above the 22- in the pic) goes to A. the other lead ( above the -25)goes to D.

After reading various threads about the filter...I had never really seen one gutted....so here it is....I thought some may be interested.
 
Knew it wasn't a ferrite bead - the function is different - but I'd never taken one apart, either.

Looks like an amplitude gate to me... that would also jive with the clipping filter function in the OBD-II ECM grounding.

Some people have good luck removing the filter on OBD-I systems; others have problems. I've never been able to figure out (reliably) what the difference is between the winners and losers in that lottery.

One thing is certain - it isn't merely an RF noise filter... if it was, then any old clamp-on coil magnet or in-line capacitance filter would work.
 
Since this is DC voltage, its line level. A capacitor in parallel is used to clip out any interference peaks or troughs. It would be a better design if it has 2 or 3 capacitor values. 22-25 microfarad would make sense, but I would perhaps do 0.1 microfarad and something 20-47 microfarad each in parallel. The value doesnt matter, other than what interference levels it filters efficiently.
 
dazed said:
Matt, Some people have.....mine has been out....but my replacement alternator has been making noise lately and these codes are popping up on me...(could be unrelated)

I get a slight hesitation than SES light comes on or an occasional stall, then SES light (limp mode activated no Cruise control etc...)

So I may need it??
Click to expand...

That sounds exactly like when I run out of fuel or when I had a clogged sock.

Turning off the truck freed the clog up. Running it it would clog back up over time, and when it starved the IP enough it would hiccup, code, sometimes stall, sometimes recover in limp mode.

It coded to the IP. Don't remember exactly which code.

Next time it does this, get out of the truck and crack the fuel bleeder whether the truck is running or not.

If indeed it is a clog the bleeder will HISS as air goes in to relieve vacuum caused by the IP working overtime to get fuel, or fuel will come out and its not fuel related.
 
I did some research on the filter harness some years back, and as per GM the only reason the yever used it was due to AM radio reception. Th electronic DS-4 IP would cause the AM radio to cut out as it emitted a simliar frequency, so the filter harness was added in. I don't have the bulletin anymore, but GM said to remove it.
 
THEFERMANATOR said:
I did some research on the filter harness some years back, and as per GM the only reason the yever used it was due to AM radio reception. Th electronic DS-4 IP would cause the AM radio to cut out as it emitted a simliar frequency, so the filter harness was added in. I don't have the bulletin anymore, but GM said to remove it.
Click to expand...

That's funny; I was told that it was there to protect the OBD-I PCM from induction transients, which the DS-4 is prone to, like all solenoid systems. The OBD-II PCM has that input-limiting circuitry built-in, which is why when a filter harness shows up on a 96 or 97, they just pull 'em off without replacing.

Made sense at the time... maybe the guy fed me a line, but the chip in that harness doesn't look like an RF choke.
 
Looks like a surface mount diode with the white stripe indicating polarity. Check it with an ohm meter...
 
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