NEED HELP Unknown Driver and No Start
- Thread starter Mramses
- Start date
friends now should i check? I did not find anything irregular. pcm has his 4 powers and his land. dark green communication cable class 2 reaches the sp205
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thanks for answering
I understand my friend. I must measure resistors from C2 65 with each power input of the pcm. What values should it have?
thanks for answering
you compare the readings since they are all 12v inputs. Looking for unusual, open, low resistance, very high.
resistance at C1 20 started to rise, rise and rise. C1 19 is equal to C3 17
resistance at C1 20 started to rise, rise and rise. C1 19 is equal to C3 17
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you are right... my eyes weren't looking at the full picture just the meter... dumb eyes (ass)...
that's probably why my second request of checking the other PCM didn't make any sense to the OP, I bet...
One other thing, tjbaker57. You notice that the battery light is on in the IPC. My understanding is that gets set by the IPC based on a command from the PCM so to me that would confirm that some form of PCM comms is happening. I am thinking the rest of the problem with IPC might be with the IPC and not PCM comms to it.... maybe...
but the resistance values I am measuring in the harness of the pcm. they are not connected to the pcm. that's fine?
How should I do the measurement?
connected the harness to the pcm and connected the battery?
Well I'm not certain of all the inner workings but I just now confirmed that with my sp205 comb removed I still have that battery indicator (the charge indicator as called in the charging circuit diagram). And it remains lit after starting the engine with the comb removed. The cluster does get a voltage signal on the class 2 network to drive the voltmeter. As you may remember I have a thread on reading the class 2 serial data.
Read from the pins of the PCM to the ground terminal on the PCM. The idea is to confirm the PCM circuits are correct inside the PCM
do this same test with the one that is currently bolted in the motor. The "zero" doesn't look good.
Ignore my post.
Can you appreciate well the values of the resistors on the 4 power pins?
in both pcm c3 17 is grounded.
and c1 21 is 1.5 Mohm check engine
c1 21 is 300000 ohm without check engine
in both pcm c3 17 is grounded.
and c1 21 is 1.5 Mohm check engine
c1 21 is 300000 ohm without check engine
As I indicated and perhaps expected, that some resistance readings should be "normal" (ie. not zero, not infinity, and maybe not high high). i would expect both units to have similar "powering circuitry" connected to incoming power... yet I know nothing of the actual circuit itself. I don't think it matters... maybe. The zero does not look right and potentially is the problem although I would have expected that to blow a fuse on the IGN 1 fuse protection.
Of course, if we had a known good PCM, we could check those...
Of course, if we had a known good PCM, we could check those...
sorry... you are correct, I see further that the IPC also has a check of battery voltage and does something although my "read" seems to indicate it is based on either PCM OR BCM confirming but maybe GM SI isn't as "clear" as it could be.
Updated 20200917: The image attached contains an error. I was on the wrong pin for C1, #59. The correct value is 4.66k
Here is what my results are.... Mine is also a 2002 PCM.
Here is what my results are.... Mine is also a 2002 PCM.
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the pcm that turns on the check engine was sold to me as good second hand.As I indicated and perhaps expected, that some resistance readings should be "normal" (ie. not zero, not infinity, and maybe not high high). i would expect both units to have similar "powering circuitry" connected to incoming power... yet I know nothing of the actual circuit itself. I don't think it matters... maybe. The zero does not look right and potentially is the problem although I would have expected that to blow a fuse on the IGN 1 fuse protection.
Of course, if we had a known good PCM, we could check those...
could that be my problem? Is it possible to check that it is faulty in the internal circuit of the pcm at pin c3 17 to ground c2 65?
Can any of your colleagues make these measurements for comparison please?
Mr baker could you help me to check if those measurements are good? although already my friend Budwich (whom I thank for continuing to help me with my problem)
What should I check the wiring circuit that feeds c3 pin 17 that may be causing the failure for the pcm in case I find another pcm?
help friends
I am unsure which pins are being tested in these photos. I will need to look further at these...
i checked both pcm. both in C3 color TAN, pin 17make sure you doubly confirm that you are on the right pin...
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Several of your pictures show you mistaken about the pin number. I suggest to recheck and be certain of the pin number you are on. Also check with the polarity reversed. Compare to my working PCM. Also,, use the smallest range of the meter that will give a result. This will mean using different meter ranges on different pins.
