Issues after reinstalling pcm (radio and other things not working)

Spalding1028

Original poster
Member
Jan 20, 2012
60
(scroll down for tl:dr)
Just a bit of back story, I got my pcmforless tune, doing their loaner program. When I installed the loaner pcm, I did the security relearn and everything went fine for the week that I had it. I got my original pcm back last night, swapped them, it started right up, and I didn't really think twice to check everything since it was late and I was tired. On my way to work this morning, I wanted to listen to the radio, noticed it was off (off as in, wasn't even displaying the time (I've got the nav/bose unit btw)) I had to press the power button twice just to get it to show the normal "off" screen, and that went away in a matter of seconds. When I got to a stoplight, I put it in park, turned it off, pulled my key out and put it back in, and started it back up, the radio still didn't work, and I noticed that it didn't make the normal "beep" that it makes when inserting or removing the key. I was checking for other things that weren't noticeably working and also found that the green light for my drl's wasn't illuminated, nor was the amber light showing they were disabled. I switched them to the on position, the green light turned on, and then switched them back to the automatic position and it went off again, finally turning on a few seconds later. When I noticed that, I tried the radio again, but still no luck...

edit: Also forget to mention that both times the battery neg cable was disconnected before any of this work was done.

tl:dr?
did pcmforless loaner program. Loaner pcm worked after security relearn.
After original pcm is reinstalled, starts right up, but drls, radio (with nav/bose), and the "beep" when the key is insert/removed don't work...
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Sounds like an unrelated fault. Perhaps the ground at the bottom of the radio stack, on the passenger side under the edge of the carpet. The chimes come from the radio, through the left front speaker, so that's not a surprise. DRLs dying are also unrelated. Swap relays 45 and 46 to see if you just lost the solid state relay that runs them.

Do you have a meter and a copy of the schematics from the link on this site to dig deeper for the missing radio power? http://gmtnation.com/f23/need-service-manuals-get-them-here-371/
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
If I turn my headlight switch to the on position, the headlights come on, so I think we can rule out a relay. As far as the radio goes, the screen is completely black. If I press the power button (once) it will show the time only in the middle of the screen like the radio is off for three seconds and then it goes black again. I can do that as many times as I want with no issue, so I can't see how it could be a bad ground. When I get home tonight, I will disconnect and then reconnect the battery to see what that does.
 

Mooseman

Moderator
Dec 4, 2011
25,671
Ottawa, ON
Sounds to me like the radio's anti-theft system has kicked in and not recognizing the VIN in the PCM and locking itself out. Was this radio original to this truck? Did you request with your tune to have the VATS disabled? Maybe a call to PCM4Less would be useful, especially since the radio worked with their loaner PCM but locked out after the tuned PCM was installed.

For the headlights/DRL, this is a coincidental separate issue.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
I'm 95% positive I had them leave VATS alone. The radio is stock to the truck. I'm gonna give them a call in a few minutes here to see what they say.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
Called P4L, they left vats alone, I guess my next step would be to talk to my buddy that works at a local dealership to see if he can hook a techII up to it >.<

update: Got a hold of the parts guy from the vocational school I went to. I'm gonna hook their techII (yeah, I got to use one of those sexy things) up to it to see if clearing out the vin from the radio will do anything for me.
 

McGMT

Member
Jun 17, 2012
621
Spalding1028 said:
If I turn my headlight switch to the on position, the headlights come on, so I think we can rule out a relay. As far as the radio goes, the screen is completely black. If I press the power button (once) it will show the time only in the middle of the screen like the radio is off for three seconds and then it goes black again. I can do that as many times as I want with no issue, so I can't see how it could be a bad ground. When I get home tonight, I will disconnect and then reconnect the battery to see what that does.

Never question the ways of the roadie.... These vehicles are electrically engineered unlike any vehicle before it... Assumptions are never good when diagnosing issues with it, always check every possibility there is. We are all here to help diagnose and fix, if you don't want suggestions on how to diag and such ask your question on the other side, they won't bother you with answers...
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
McGMT said:
Never question the ways of the roadie.... These vehicles are electrically engineered unlike any vehicle before it... Assumptions are never good when diagnosing issues with it, always check every possibility there is. We are all here to help diagnose and fix, if you don't want suggestions on how to diag and such ask your question on the other side, they won't bother you with answers...

I'm sorry if I missed any sarcasm. I'm sure The Roadie has had more time working around cars than I have, and I respect any input that I receive on here, but I've been tearing through electrical systems on vehicles newer than these for the past 4 years, including my last 2 years of high school in which every single day (except for weekeds) I was learning to work on vehicles. I was simply stating what I had observed. Again, if that was sarcasm, I'm sorry for not being able to tell you were sarcastic, but if you are going to be a jerk, please stay out of my posts as I would like to hear from those who are trying to be helpful.
 

MAY03LT

Member
Nov 18, 2011
3,425
Delmarva
Spalding1028 said:
As far as the radio goes, the screen is completely black. If I press the power button (once) it will show the time only in the middle of the screen like the radio is off for three seconds and then it goes black again.

I've seen a bose/nav do that. Removing the radio fuse in the rear fuse block for several minutes brought it back to life. Not sure if that will fix yours but it might be worth a shot if the tech2 won't communicate with it.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
MAY03LT said:
I've seen a bose/nav do that. Removing the radio fuse in the rear fuse block for several minutes brought it back to life. Not sure if that will fix yours but it might be worth a shot if the tech2 won't communicate with it.

Thanks, I'll give that a shot when I get out of work tonight
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
MAY03LT said:
I've seen a bose/nav do that. Removing the radio fuse in the rear fuse block for several minutes brought it back to life. Not sure if that will fix yours but it might be worth a shot if the tech2 won't communicate with it.

Fuse pull did the trick! As far as drls go, they are on, I was just confused because the green indicator light wasn't on.
 

MAY03LT

Member
Nov 18, 2011
3,425
Delmarva
Coolness. Wish I had an explanation for why that happens. Thanks for following up with the fix!:thumbsup:
 

Mooseman

Moderator
Dec 4, 2011
25,671
Ottawa, ON
Excellent! Good to know. Maybe it just needed to reset itself. With these trucks, you never know.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
I'm moving away from random//bizarre occurrences and more towards maybe pcmforless messed up???

ABS/BRAKE issue
When I took my lunch at work today, I drove maybe a total of 4 miles. Halfway through the trip, my Brake and ABS lights came on. I pulled over, brakes worked fine, checked fluid which was fine, got back to work and looked around on here (I figured it was something different). As I was leaving work, it kicked on again, drove maybe a mile, and as I was making a stop my abs kicked in, so I thought it could be a wheel speed sensor going bad. Made the trip home with it chiming every 5 minutes (it would flash off then on and chime), once it even did it 3 times within 2 seconds. I got home, looked over the ground, snapped the bolt when trying to get it out and relocated the ground about 6" back to one of the bracket mounts. Started it up, light didn't come on and I let it sit for a few hours till I was ready to go somewhere.

Unkown driver/batshit crazy
A few hours after I made the ground repair, it was time to leave my buddies house and head home, got maybe 30 feet away, the abs/brake lights flashed for a quick second and went away. Got to the corner (maybe 100 yards) everything dimmed out for a quick second, dic came back up showing "Unknown Driver", only working gauges were tach and speedo. ABS, Service 4WD, Airbag, battery, and Check gauges lights came on, just about every lighted switch (including doors and 4wd indicator) went black, switches in the door did not work (window or lock/unlock), could not drop into 4x4, rear wiper was unresponsive, and the nav unit displaced a nice message saying "anti theft system" or something like that. It drove perfectly, but had about as much electronic functionality as my '64 nova... Turned it off, started right back up displaying "Driver 1" and got it home. Did some googling, disconnected the neg batt cable for 10 mins and reattached my pcm connectors to rule them out, got it to do it again 2 more times. Drove it home and it ran perfectly with the exception that the brake and abs lights were still on... I was messing with it some more and I actually got it to display "Driver 2" with the driver one key inserted, drove it around the block and no "Unknown Driver" message popped up. Got it home, shut it down, pulled the key, restarted it, it said "Driver 1", let it sit for a second, and as soon as I put it in drive, I got the "Unknown Driver" fiasco again. I can jiggle the key in the ignition and it does nothing. I'm not ruling out faulty ignition switch, but I find it odd that these issues surfaced after I installed my tuned pcm.

It drives fine, I'm going get up early in the morning and swap the loaner pcm (which I had absolutely NO issues with) and see what that does. If that fixes things then as a last resort before I contact pcmforless, I'm gonna put the tuned one back in and see if I can force a security relearn with a techII or at least look into what might be causing these issues. :hissyfit:

My cluster:
View attachment 22008

update: I swapped in my loaner pcm that had no problem the past week, and drove it a good 30 miles with no issues at all. Did a couple 0-40-0's and could not get the unknown driver issue to replicate. ABS and Brake lights still came on, so I'm thinking that is something separate. I noticed that my bluetooth pcm scan tool would connect to my phone, but could not recognize a vehicle when it was in unknown driver mode. I hooked a techII up to it, and when I tried to do something as simple as scan for DTCs, I got a message from it saying that it could not communicate with the vehicle. The scan tools will get 12v off of the connector but cannot communicate with the pcm, abs, or even the nav unit when in unknown driver mode.

My next step is going to be to contact pcmforless and politely ask for them to reprogram the pcm. I have good faith in them from reading all of the positive reviews on here, and I love how they have my shift points set up... Just wish I could regain some functionality on my trailblazer :frown:
 

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Spalding1028

Original poster
Member
Jan 20, 2012
60
I'm not worried about the abs issues, I'm thinking that's something different since it stays on even with the loaner pcm, but somewhere it looks like the pcm is almost losing communication with the vehicle. Especially if a tech II can't even communicate with it.
 

Mooseman

Moderator
Dec 4, 2011
25,671
Ottawa, ON
Just a wild hunch, did you check all the fuses? There is one for the aux power outlet that also powers the OBDII connector (which could explain the loss of communication by the Tech2). Other than that, maybe a flaky BCM? Did the Tech2 communicate properly with the loaner PCM? Just shooting in the dark here on this one. Probably your best bet would be to talk to PCM4Less directly.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
Mooseman said:
Just a wild hunch, did you check all the fuses? There is one for the aux power outlet that also powers the OBDII connector (which could explain the loss of communication by the Tech2). Other than that, maybe a flaky BCM? Did the Tech2 communicate properly with the loaner PCM? Just shooting in the dark here on this one. Probably your best bet would be to talk to PCM4Less directly.

Everything (with the exception of the abs and brake light) worked normally with the loaner. I tried for a half an hour and could not reproduce the unknown driver issue with the loaner in. Even with the tuned pcm, I could get a read on it unless the vehicle went into unkown driver/security mode (I'm thinking it's a form of security mode that the vehicle goes into) and then it was like all of the wires on the dlc with the exception of +12v and ground were cut. For the week that I had the loaner, I had no issues whatsoever. Everything that's been described in this thread has happened after I installed the original tuned pcm, and nothing like this has ever happened before I sent it out for the tune.
 

Mooseman

Moderator
Dec 4, 2011
25,671
Ottawa, ON
Looks like you have narrowed it down to the tuned PCM. Again, a call to PCM4Less would be in order. Maybe an error with the VIN? I had VATS disabled on mine for just this very reason as it could leave you stranded for no apparent reason.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
Looks like Marshall has been in here at least once. I'll give them a call on my lunch break today to see what we can get set up. I just wanted to see if there was any other input before going that route.
 

marshall@pcm

Member
Dec 6, 2011
260
Mooseman said:
Looks like you have narrowed it down to the tuned PCM. Again, a call to PCM4Less would be in order. Maybe an error with the VIN? I had VATS disabled on mine for just this very reason as it could leave you stranded for no apparent reason.


Impossible for there to be a VIN error. We never changed it. He sent his stock one in, we flashed it, and sent it back out. Very weird problem!
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
Any chance I could send it back to you guys to have you delete the vats and see if that clears it up? I hate to try hit and miss things, but unless someone else has an idea what it could be, I'm stumped
 

MAY03LT

Member
Nov 18, 2011
3,425
Delmarva
Spalding1028 said:
I hooked a techII up to it, and when I tried to do something as simple as scan for DTCs, I got a message from it saying that it could not communicate with the vehicle. The scan tools will get 12v off of the connector but cannot communicate with the pcm, abs, or even the nav unit when in unknown driver mode.

Does the scan tool communicate with the loaner pcm in? If so, are there any U codes in the BCM?
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
MAY03LT said:
Does the scan tool communicate with the loaner pcm in? If so, are there any U codes in the BCM?

It communicates fine. I'll have to wait until Tuesday to see if I can pull any codes from it.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
I'm going to drive it for a few days with the loaner in it. As much as I wish it was something as simple as a bad flash, I want to give P4L the benefit of the doubt in this. If I can rule out as much as possible before deciding it's the pcm, I'll feel better about involving them in this.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
Update: good news for p4l, not as good news for me... We can rule out a bad flash. I had the loaner unit in today and it went crazy again on the way home from work. Looked over a few threads and called a stealership for ideas. Potential culprits are bcm, ignition switch, and cluster. I'm also half tempted to pick up a tech2 for about $2k from gm dealer equipment if it's bcm or cluster so I can do the reprogramming myself and also for future nightmares. (i figure after I use it 20 times it'll pay for itself)

Other observations I've made are that at least once the key would not turn in the ignition after it was inserted, had to release the key and then I could turn it like normal. Also, I'm not sure if it's because I didn't do the security relearn with the driver 2 key in addition to the driver one key (possible to do both?) but it would see the driver 2 key as driver 1. Finally, I was able to remove the key and it would not return the seats to the "easy exit" mode. I had to insert and remove the key at least 5 times for it to see that a key was removed (didn't do this all the time). I'm leaning more towards ignition switch than bcm and cluster.
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
After some looking, I found the issue. The ground for the ebcm (on the frame just in front of the drivers door) was good enough for it to occasionally function, but was going bad, causing everything else to go crazy. I left that ground in place, but tied off another wire from it and gounded it to the steering column. If I disconnect the ground I made, it goes crazy, but as soon as I make the ground again, everything goes fine again. I'll be in the process of finding a better ground for it.
 

McGMT

Member
Jun 17, 2012
621
Spalding1028 said:
After some looking, I found the issue. The ground for the ebcm (on the frame just in front of the drivers door) was good enough for it to occasionally function, but was going bad, causing everything else to go crazy. I left that ground in place, but tied off another wire from it and gounded it to the steering column. If I disconnect the ground I made, it goes crazy, but as soon as I make the ground again, everything goes fine again. I'll be in the process of finding a better ground for it.

I thought there was no way it could be a ground? oh well, just deny it and hope nobody reads the beginning...
 

Spalding1028

Original poster
Member
Jan 20, 2012
60
McGMT said:
I thought there was no way it could be a ground? oh well, just deny it and hope nobody reads the beginning...

I'll admit that I was wrong on my opinion earlier. I had checked the ground The Roadie was referring to and decided we could rule it out. I did not think that a bad ground on a module other than the bcm or the cluster would cause this issue. The Roadie was correct in the fact that they were unrelated to the tune which I verified a few posts back.

I'm still fairly new to the site as I'm starting to use it more and more. I understand a lot of people here came from "the other side" that you referred to, to get away from something that was unhelpful. But seeing how you've been toward someone who came here for help does not give a potential new member much hope for finding people who are willing to help. And if I hadn't seen how helpful other members have been, my first thought would be to go to "the other side". I'm not here to cause trouble with other users; I bought a vehicle, fell in love with it, and found a good enthusiast site. Again, I will say that if you wish to come in on one of my threads in the future, all I ask is that you be respectful towards me as I will do my best to be respectful towards others on here.

As for everyone else that posted their ideas (including you, Roadie) thanks for trying to help. I'm sorry that I had to make this post as it is, but I do appreciate the help and I hope to be around to help another member in need if I can contribute to the conversation.
 

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