98 C5 PCM "no comm"
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From: Andrews AFB Maryland
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From: Andrews AFB Maryland
Yea I dunno, I can't really complain though bc they didn't charge me for labor bc they couldn't figure out what was wrong with the car. So I'm thankful that there's still a few places out there with some integrity. they did however do some phenominal body work for me. I'm going to mail my bcm out tomorrow and have it checked. And also found a company that can repair/replace my pcm as well if need be. Just waiting on a reply back from them so I can send it. Then I'll see where I'm at after I know both of those are in good working order.( hopefully it'll be behind the damn driver seat)
Melting Slicks
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The PCM is on a fuse, I've seem many time you could not communicate with a PCM (in a running vehicle) because the fuse was popped, usually because of something plugged into the cig. lighter that popped the fuse the obd port was on too.
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From: Andrews AFB Maryland
I already checked the fuses visually and with a meter, and I checked the wires under the fuse box to make sure they weren't loose
Melting Slicks
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Did you try a scanner plugged into the OBD port and the DIC to get any info? Did you pull the battery to see if there was ever any acid leakage from the battery onto the PCM?
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From: Andrews AFB Maryland
Yea I borrowed a scanner from Advance, and checked the codes though the dash. All no comm. And before when this problem was intermittent, when the car would run there were no codes except for general loss of comm. The pcm looked clean, no acid signs of at all.
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From: Andrews AFB Maryland
Melting Slicks
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https://www.corvetteforum.com/forums...-there-is.html
It's sutile how the pins get twisted in the harness.
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Let's take a simple battery charger using 60 cycle AC and converts it to DC and does it using the Full Wave conversion and produces 60 square waves and not 30. This is like turning the electronics on and off 60 times a second when a battery can't help filter or mitigate this condition.
You may ask yourself then why does my computer power supply not damage the electronics? Good question. It is because the power supply is much more complex and actually makes a virtual true DC current. At least as close as possible.
Mr. Sam P. E.
You may ask yourself then why does my computer power supply not damage the electronics? Good question. It is because the power supply is much more complex and actually makes a virtual true DC current. At least as close as possible.
Mr. Sam P. E.
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From: Andrews AFB Maryland
Hey could a transmission issue cause the pcm to go into a "safe mode" and cause the issues I'm having. The more I think about it, the more I don't think its a coincidence that this happened they day after I changed the transmission fluid, which I accidentally got everywhere bc I loosened the wrong bolt on the trans,( the square one on the top) so fluid blew everywhere for a sec.
Melting Slicks
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Hey could a transmission issue cause the pcm to go into a "safe mode" and cause the issues I'm having. The more I think about it, the more I don't think its a coincidence that this happened they day after I changed the transmission fluid, which I accidentally got everywhere bc I loosened the wrong bolt on the trans,( the square one on the top) so fluid blew everywhere for a sec.
Racer
Joined: Nov 2012
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From: Coos Bay Oregon
It all sounds to me like you have a major grounding problem. I say that because you have several unconnected things (windows, PCM, coil packs, etc.) happening at the same time. If you will go to the beginning of the C5 tech forum, you will find a thread call "electrical issues." or something like that. The first thing mentioned is grounding points. You car is 17 years old, so your grounding points are probably corroded. That will cause more problems than you'll ever believe. I would clean those up in addition to the grounding points you already cleaned up. Then you can clearly look at anything else that may be screwed up and be more sure about what you are looking at.
Good luck with it.
Good luck with it.
Safety Car
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From: Portland OR
Sounds to me like you have a short in the comm buss.
More likely than not in the pass side door wiring.
Have you grabbed the door accordion tube and given it a good shake? Sounds dumb, but it's a common issue.
More likely than not in the pass side door wiring.
Have you grabbed the door accordion tube and given it a good shake? Sounds dumb, but it's a common issue.
Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Find the one with FOUR wires. Pop the TOP off of the connector and see if you resolve the issue.
Let us know how it goes.
Bill
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From: Andrews AFB Maryland
I 're 're 're checked all the grounds, the wires in the doors, disconnected the STAR connector with 4 wires( which only temporary solved the problem, it came back after a few days) I also disconnected both STAR connectors and jumpered just the pcm and bcm together and I still couldn't get it to start. I mailed out my pcm and bcm to a repair company to have them checked to see if either of those are my issue, they haven't got there yet though.
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
When the problem happens or is happening, do not change ANYTHING and read the voltage on the "Hot In RUN and START" supplied fuse/s test points to chassis ground for the BCM and PCM .
See if you have full battery voltage on those fuss at/during that event.
Bill
See if you have full battery voltage on those fuss at/during that event.
Bill
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From: Andrews AFB Maryland
Well hopefully when I get my pcm/bcm back I'll be good to go. I can't do much now till I get them returned. But I did do that before and after I changed my ignition switch and it matched the battery voltage