Computer Install

[ss_silverado01]

Hey guys, I need to replace my 2001 Silverado's computer. We have a new one, but I'm not sure if there's a certain procedure we would have to go through to program it after it's installed. Any tips and/or advice would help out a lot!

I've looked around on the forum, and cannot find the advice I need.

It's a 5.3 2wd if that makes any difference.

Thanks!

[bobcat5544]

1st off why are you replaceing it and how many miles on you truck?

[ss_silverado01]

1st off why are you replaceing it and how many miles on you truck?

253,000. having too many issues with it. Either I have my normal perfectly running silvy, or I have this monster that doesn't shift, doesn't get fuel, dies, acts like the battery's dead, etc, etc. It gives me a ton of problems.

[bobcat5544]

How did you find out it was the PCM

[ss_silverado01]

I have been having computer issues with the truck since I got an after market alarm put on it 3 years ago.

My truck has been the most awesome vehicle I've owned/driven. It has not given me many problems, so for it to all of a sudden start acting like the battery's dead (battery n alternator are brand new), acting like it has a bad fuel filter (replaced 2 weeks ago), alarm quit working, n transmission to start severely slipping n going into failsafe mode, it has to be the computer. It gives me more problems, but those are the main ones.

All those problems happen at once, not just one or two at a time. If it's not acting up, you'd swear it was a brand new truck it runs so well, shifts like a dream, etc. It's definitely electrical, and I got my money on the computer, since so many things happen at once. I'm not the only one that thinks the computer is at fault.

[bobcat5544]

What is the alarm brand and/or model is it.

[ss_silverado01]

Viper 2 way. Got it 3 years ago. It's got the remote start, gps, and alarm.

All my mods are listed in my sig.

[bobcat5544]

Before getting to deep into this. Did you check to make sure the pos/neg battery termanials are tight and have no corriosion and also check the positive cable to the fuse block and to the red junction block between the engine and drivers fender well.

[ss_silverado01]

The battery's brand new.

N yea, I checked all that.

[bobcat5544]

The reason I am questioning replaceing the PCM is

1. It doesn't act up all the time. a bad PCM will usally act up all the time.

2. You have transmission shift problems. The trans has it's own control module

3. The problems did not start until after the alarm was installed and when adding these alarms there is a lot of wire being spliced into the trucks wire harrness. Splicing into the wrong wire or poor install job will cause all kinds of problems.

I can bet it is spliced into the main power wire to the ignition switch. These alarm systems utilize mechanical relays and normal vehicle movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions of the ignition circuit can put power from it and not supply the power and signal that the modules need.

 

If you want to test this theory just unplug the viper alarm module and see if it keep happening.

[ss_silverado01]

The transmission has been rebuilt, n never works properly after. It's been rebuilt a few times, since the rebuild doesn't seem to do much good. The tranny shop itself agreed that it was most likely a bad computer, since they replaced everything pertaining to the trans. I also know someone with similar trans problems. Even with a brand new totally different unit, the truck did the same thing. Diagnosis? Bad computer.

As for the alarm, I'm pretty sure it was a bad install. I would not be shocked.

As for the rest of it, then why is my truck throwing me 5 different problems at once if it is something else? The fuel pump is newer, the fuel filter just got replaced, the battery and alternator are new. There is no reason for that truck to act that way on occasion, then be a perfectly normal truck the rest of the time. I do agree however, with your statement about it doing it occasionally. That's weird to me as well, but could it not be the computer possibly has a short, or glitch?

Also, the alarm has been disconnected several times, n even removed totally from the system. It still acts up with it uninstalled. Acting up via the alarm means, the alarm will totally not work, or I get a start-kill type issue, where the truck starts, immediately kills, n will not totally start for over 20 minutes. It does this regardless of if the alarm is connected.

Sorry if I'm seeming a lil pissy, but this is driving me bonkers, and nobody knows what else the problem could possibly be caused by.

[bobcat5544]

I can understand the fustration. I worked for GM Corporation for 7 years as a program tech, and also did tech support on electrical problems like your dealing with. I have seen some of the most screwed up s**t happen and tech have put days into a job for something that should have been found in an hour.

 

I have had one case where a control module did have a loose circuit inside which caused a vehicle to act up at time and then work normal.

 

If you want to go over the problem more let me know or after you replace it if it does not fix your problem let me know and I'll go over every thing with you to see what could have gotten missed

 

To answer you main question were did you get the PCM from is new or used

[ss_silverado01]

It was given to me by a couple of friends. That being said, it is used. lol

I am taking the truck back to the alarm shop today to see if we can fix the alarm issue. The remote gets no response from the truck, indicating that the remote wire is bad. I'm having that replaced today.

It's still not going to fix my other issues. I haven't had the truck much lately. I've actually pretty much temporarily swapped cars with my boyfriend. As far as I know, it hasn't been giving him any problems lately. It's not an everyday occurrence, but when it does happen, it will most likely act up a couple of times that day. The main thing it will do is start, then immediately kill. But, if you take the key out of the ignition, and open, then shut the drivers door, it will crank and stay running. I've had it act like the battery was dead after it started then killed. Totally dead. No dash lights, no radio. Nothing at all. If you try it a couple times after that, it clicks, like it doesn't have enough power to start, then eventually will start. Both the battery and alternator are about a year old. My volt gauge reads perfectly normal through all this, even when it "plays dead".

When all of this happens, I also get this great fuel-starved attitude from it, as if the fuel filter is clogged. Stop at a stop sign, it dies. Slow down below 10 mph, it dies. Give it gas, it's ok. Runs a lil choppy doing 55 mph, but not horribly.

And then on top of all this, typically my trans goes into fail safe mode. I'm sure you know this means third gear only. If it doesn't, it will slip into 3rd gear extremely rough each time. I already have a light slip going into 3rd gear, but it gets 10 times worse when it does all this.

The truck really has no other problems. The check engine light comes on once in a while, both when it's acting right, and when it's not, but that is about it. It runs perfect, with no issues.

[bobcat5544]

It will take me a few hours to verify, but I'm almost positive what it could be. You stated you had to open and close your door to get it to start again. I've have one other truck do the same thing. I just have to find that file and make sure it is simular to yours. I believe it had something to do with a ground, power, or ignition switch problem.

 

Just give me a few to find that file.

[ss_silverado01]

Alright. Appreciate that. I'd hate to get rid of this thing n come to find out it's not a major issue.