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No Communication with scanner

and on changing the fluid. NEVER FLUSH it! some of the jiffy lube shops like to tell folks it needs to be flushed. that will destroy a trans. any muck that is in the cooler or lines breaks free and causes a domino glitter bomb effect!
 
Yeah I read about that, definitely staying away from jiffy lube. I will just get a drain and fill with a new filter. Transmission shop near me would have this whole thing done by now if it weren't for communication issues. Found a local shop with 25+ years in business that deals with electrical so ill be calling them in the morning. I will follow up with any progress.
 
MattP said:
Last question towards pavaltolz, how would I specifically check the connectivity between port 2 and ecm?
Click to expand...
Sorry for the delayed response (Anniversary Celebrations and all).
I had to do a little digging in the 1997 manuals and (for us diesel guys) where you have a Vehicle Control Module (VCM) near the Brake Controller and the Under Hood Fuse Box vs. my 6.5. ECM next to the Glove box...my learning curve, no condescension.
Probe for continuity between the Data Link Connector's Pin 2 and the VCM's black connector, pin 11.

IMG_8855.jpg

I'll search the other books for info. Here's the Schematic in the meantime.
 

Attachments

  • DLC diagnostics.pdf
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dbrannon79 said:
and easy way to check the brake light switch is get it into lockup, then tap the brake slightly without moving your foot off the go pedal while cruising at a constant speed. watch your tach. you should feel and see the TCC release, RPM should increase about 200 or so on the tach.
Click to expand...
Did this today and experienced exactly what you described. I didn't feel any issues with the lock up today either. Have an appointment next Wednesday to try and get communication back, have a weird feeling it's the ignition switch. Going to see if I can find ways to test it.
 
TV cable? Not much on youtube but that could be a reason why the truck is shifting a bit late right? Im thinking it's just a guessing game to fine tune it. Also as of like 3 days ago every time I start the truck the pedal feels stuck. Only when I start it. Any correlation to any of my other issues?
 
I'm not sure if your model would have a real throttle cable to the engine or if it's drive by wire where there is just a sensor on the pedal. you might check if it has a cable to the throttle body, it's not kinked anywhere or the butterfly in the throat is carboning up. iirc there is a couple of GM TSB's out there where removing the throttle body and cleaning with some brake cleaner spray and an old tooth brush does wonders. again you might need to communicate with the ECM to reset it. I know on trailblazers and some other models you have to reset the ECM so it can "re-learn" the engine after a cleaning. otherwise it will run like krap making you think you broke something!
 
Shop looked over everything ended up getting communication with ABS but nothing from the transmission or engine. He ended up telling me to take it to the dealer to have them reflash the ECM. He's never seen it where it will communicate with the ABS but not the ECM. Will know Tuesday if the reflash fixes the issue. Tried to reset ECM by unplugging negative terminal to battery and jumping positive in battery to disconnected negative terminal but all i got out of that was my radio no longer works.
 
Ya gotta love technology! iirc GM did put out a tsb on a few models for an ECM re-flash / software update for silly things like this. if the dealer comes out and says that your ECM is bad, ask them if you went and snagged one from a similar model out of a pick a part yard, will they flash it with your trucks software including your VIN info. that will be much cheaper than you having to purchase a new ECM from them!
 
Well Doug I didnt see this comment in time, dealer mentioned something about a recall I believe. But yeah after diagnoses they told me the entire ECM was bad and they went ahead and ordered a brand new one from GM down in Arkansas. Will have it here Friday and they are gunna put it in Monday morning. I believe the dealer had a diagnostic fee of 300$ and the part was 391$ after the 79$ core charge. They said 168$ to put it in so somehwere around 800$ just to get communication back so I can see whats going on with the transmission. I thought I read that a bad ECM can send bad signals and cause issues with overdrive / transmission in general but im not sure.
 
Yeeouch!! That's gotta hurt the pocket book. I do hope they guarantee that if this doesn't fix the problem, your not out the cost of the new ECM and some credit for a mis-diagnosis. Hopefully the tech working on your truck back probed each and every pin to the ECM verifying there is no possible issue before ruling a bad ECM, at least for a $300 diag fee.
 
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