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This pic is of entire circuit board w Corroded Diode>I plan to Replace.
Notice its theonly diode of its kind on the entire board.
Thered pointer points to the Diode w the label GONE. (SEE ATTACHED FILE for ADDITIONAL PICTURES including my ECM)
Hi to everyone. Im TJ, a new member with a98 Base Coupe. This is my first ever post on this website. I hope youre all enjoying your cars and/or projects !!
My PCM circuit board has a BAD DIODE on it, and, because money is tight right now and a repair service costs a few hundred bucks, my GOAL is to replace it as a Do-It-Yourself project.
Im hoping this can happen thru one of these Scenarios (preferably A):
Scenario A ----- from experience, someone knows, or can tell me how to ascertain, the diode Type and Valuein Electronics Industry standard terminology: (EXAMPLE: Type: Zener diode; andValue: 5.1 Volts) ---- so I can then purchase the proper generic component from an electronics supplier such as Digi-Tek etc--VS--trying to acquire a good used GM diode. I realize this is a long shot.
Scenario B ----- someone can come up with thecorrect good used GM diode theyd be willing to sell me --OR-- tell me where or how I could a obtain one.
Oneproblemhere is that once my tech friend removed the corrosion from the diode, thepart number / labeling wasgoneas well. (See 1st picture: Zoomed in on diode at end of red pointer). I searched the Internet for an image of a similar circuit board with that same diode to get the part # off of it NO luck. If anyone could provide that part number itd be a step in the right direction.
FYI thecorrect PCM Part # is 19332289,which is ALSO found in a 98 Camaro and a98 Firebird ---- AND 16238212is stated to also be a valid GM part # per Car-Part.com, as well as ECM service Flagship One. Additionally, multiple Techs have said that GM put the diode I need onto similar circuit boards inOTHER ECMsthat cant be used in a 98 Vette ---- but I dont know which cars or part numbers for those ECMs.
I appreciate any help or input ! Thanks a lot ! TJ
How do you know the diode is bad? If you are going to replace the diode anyway you can carefully remove it and test it with an ohmmeter or a diode checker. You can do this with an ohmmeter by measuring the forward and reverse resistance. It should read infinite in one direction and a steady resistance in revese The reading will depend on the DMM current source and scale used. Check it on all scales.
Thanks for responding. I was told that this diode is, or most likely is, bad and that replacing it should resolve my ECM failure -- told this by a sharp auto expert who has repaired multiple ECM’s before (but that’s not his main thing). So, the FACT IS I’m not certain the diode is bad and I don’t know if he did any actual test of it in place.
QUESTION: Can you tell me if I can get ANY valuable information by using my Harbor Freight multimeter, in Diode Test Mode, on the diodewhile still installed on the circuit board ? ______ (FYI -- When I saidI’llreplace the diode, I meant I'll have mylocal electronics repair expert switch out the diode. That’s NOT something I personally can do ------- and ALSO my personal electronics knowledge is pretty limited.)
PS – Re what you used to do (in your Biography) – Shuttle etc.Holy Crap !!! Really cool !!
You can try measuring it, but without knowing what's in the circuit it could read anything. You would have to unsolder or clip one side of the diode and then measure it. This subject really belongs in the tech section. What codes were you getting when you read them via the DIC.
Last edited by Vetteman Jack; Sep 6, 2022 at 10:28 AM.
I don’t have the tools or expertise to desolder and remove components, but I might be willing to clip the midpoint of the leg of the diode for testing --- BUT ONLY if the following is true: A. ONLYIFthe test will prove that the diode isdefinitely good or definitely bad !!, (even ending up being only pretty sure is NOT worth trying this in my mind) ____ AND B. ONLYIFthe the leg can definitely be soldered back together withnormal function restoredIF it turns out the diode tests as definitely good.
Phil, can you tell me if BOTH A & B are true?
PS – RE you’re mentioning that“This subject really belongs in the tech section.”Is that because there are more technically minded people there to contribute, or is this content actually “inappropriate” for the C5 forum? (I honestly don’t know because I’m new.) Let me know if there’s something I need to do about that. Thanks
Last edited by Vetteman Jack; Sep 6, 2022 at 10:29 AM.
QUOTE:
What codes were you getting when you read them via the DIC.
Oh yeah, my dash display was reading “Reduced Engine Power,” and
my cheapo “HyperTough” Scanner gave me DTC codes: 0606 “ECM/PCM Processor” and 0518 “Manufacturer Control.”
My friend’s Snap-On Scanner said something like “Internal PCM problem.”
QUOTE:
You can try measuring it, but without knowing what's in the circuit it could read anything. You would have to unsolder or clip one side of the diode and then measure it. This subject really belongs in the tech section. What codes were you getting when you read them via the DIC.
I dont have the tools or expertise to desolder and remove components, but I might be willing to clip the midpoint of the leg of the diode for testing --- BUT ONLY if the following is true: A. ONLYIFthe test will prove that the diode isdefinitely good or definitely bad !!, (even ending up being only pretty sure is NOT worth trying this in my mind) ____ AND B. ONLYIFthe the leg can definitely be soldered back together withnormal function restoredIF it turns out the diode tests as definitely good.
Phil, can you tell me if BOTH A & B are true?
PS RE youre mentioning thatThis subject really belongs in the tech section.Is that because there are more technically minded people there to contribute, or is this content actually inappropriate for the C5 forum? (I honestly dont know because Im new.) Let me know if theres something I need to do about that. Thanks
It will tell you if the diode is shorted, open or leaky. As I see it, if your giving it to someone to replace it then it doesn't matter if you clip it and measure it. Either way it's going to be replaced. It looks like it's a low current diode so you can probably get away with just soldering it back together.
HEY I’D LIKE TO KNOW WHAT YOU THINK of this idea someone suggested to me, AND my response to it.
HE SAID, “If after a while you CAN'T FIND this diode and it is in fact BAD, THEN I would just buy a low signal diode and put it in the circuit and see if it works.Sometimes diodes are put in circuits for electrostatic protection.
To which I SAID, “That sounds like an awesome idea to me !! PROVIDED THAT: A. Someone can tell me EXACTLY what diode I can buy and use as a trial,
AND B. There would have to be NO CHANCE that doing this could cause or allow damage to my ECM when I fire it up in my Vette as a trial – meaning, affecting the ECM in such a way that, if I DID later send it out for repair, the Repair Service might tell me it’s now UNrepairable as a result of trying a non-compatible / interchangeable diode !!! ”
So Phil, if you don’t mind my asking,what do you think? (FYI – I don’t know what his background is.)
After doing some.searching I could not find a picture of a good board. I did find a picture of a bad board on this forum with the same corroded diode from 2018. This is odd how only this diode has corrosion. If you can trace the circuit to the correct external pin it would help determine what function the diode performs. Since it looks like one side of the diode is going to an external pin, you can just read the resistance in both directions and see what you get. Could not find a definition of code 518. 606 is internal fault. What were the codes via the DIC.
Last edited by Vetteman Jack; Sep 6, 2022 at 10:30 AM.
OP, I would not try replacing the diode. First I would cleanup the corrosion around it.
Unless the body of the diode is damaged it is probably good. What you have is possible moisture damage from bad seals on the connectors.
98 ECM DIODE Replacement - Pls Help Find
and/or projects !!
