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LMC Truck



Username Post: 2000 Silverado ECM Change        (Topic#347110)
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-12-17 02:20 PM - Post#2707500    

If I replace my ECM w a used one w the same part number, what has to be done to program it?



 
LMC Trucks
jktucker92 
Silver Supporting Member
Posts: 92
jktucker92
Reg: 02-05-17
09-13-17 06:07 AM - Post#2707551    
    In response to crazycoyote

The program has to be loaded into the ECM using a flash programmer. The easiest way to do this is at the dealer. They may have the ability to program it out of the vehicle, but I've never asked. In general, they program it while it's in the vehicle, and I think the charge is $75. There are a few flash programmers out there that can be purchased, so there may be others that can program it around you (I have one).
There are lots of parameters stored in the PCM, that define a vehicle. Many of those parameters are similar from vehicle to vehicle for the same engine. Some parameters will be so different that the engine won't run (such as the difference between a V6 and V8), but others would be just a nuisance (such as the gear ratio for the speedo, and lockup points on the torque converter). If the PCM came out of a vehicle with the same engine and transmission, the truck may run without reprogramming. You should still have it programmed, but it may allow you to drive it to the dealer.



 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-13-17 04:54 PM - Post#2707603    
    In response to jktucker92

Thank you for the information. I have been told and saw on youtube where after a ECM change they had a no start condition and after a sequence of key on and off for different times it would then start. Trying this with mine did not work. It came off a 99 Suburban or Tahoe with a V8. The part number was the same. The only difference I can see would be possible gear ratios as you described.



 
jktucker92 
Silver Supporting Member
Posts: 92
jktucker92
Reg: 02-05-17
09-14-17 07:35 AM - Post#2707633    
    In response to crazycoyote

I don't think replacing the PCM requires the VATS relearn procedure. That would be required to replace the BCM or ignition lock, but I don't think PCM is part of the relearn. It's a lengthy process that takes ~ 45 minutes to complete. If it is a VATS problem, then your security light should show a problem.
You mentioned that the new PCM came out of a '99 Suburban. Is your truck a diesel? If it is a diesel, then I'm not sure why it won't start. The diesel PCM should be the same from '97 to '00 since it's the same 6.5L motor.
If it's a gas motor, then the PCM is different between a '99 Suburban and a '00 Silverado. The Silverado Gas motors are the newer LSx variant motors (4.8, 5.3, 6.0) and the '99 Suburban uses the old 5.7L that is a completely different motor and requires a different PCM. Should be PN 9354896



 
rockfangd 
"4th Year" Gold Supporting Member
Posts: 2215

Age: 31
Loc: Utica ny
Reg: 04-13-10
09-14-17 04:56 PM - Post#2707671    
    In response to jktucker92

I am pretty sure reprogramming is necessary as the vin information will not match

Old School GM fan FOREVER


 
1983G20Van 
Super Senior Member
Posts: 3650

Loc: Bedford, Texas, USA
Reg: 11-13-02
09-15-17 02:37 PM - Post#2707745    
    In response to jktucker92

  • jktucker92 Said:

If it's a gas motor, then the PCM is different between a '99 Suburban and a '00 Silverado. The Silverado Gas motors are the newer LSx variant motors (4.8, 5.3, 6.0) and the '99 Suburban uses the old 5.7L that is a completely different motor and requires a different PCM. Should be PN 9354896



NOT completely accurate. The OP never said what engine he has. I have personally reflashed a Black Box PCM in a 2000 GMT800 with the 4.3 V6 to swap the truck from a 4L60E to a 4L80E. It very well could be the correct PCM, but the wrong flash.

ALSO some of the bigger trucks the C3500s carried on as the GMT400 body style into 1999 and 2000. I know you could get a 2000 Tahoe that still had the same 5.7. Hell in Mexico you got the 5.7 in a GMT800 with the 5spd behind it, even in a GMT800 2002 Tahoe.

1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals


Edited by 1983G20Van on 09-15-17 02:40 PM. Reason for edit: No reason given.

 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-16-17 03:50 AM - Post#2707800    
    In response to 1983G20Van

My 2000 Silverado has the 5.3. 1999 was a changeover year where they built both. My pcm and the one from the Suburban are both part # 09354896. with the one from the Suburban my truck cranks and gives an occasional kick like it might start but won't. I put my old one back on and truck starts but im sure it will still run horrible part of the time as it has been doing. I am thinking its in the pcm as i get no codes. I have changed fuel pump and checked pressure and regulator. I changed coolant temp sensor and the mass airflow sensor. Truck starts hard then spits and sputters and may stall. then it will drive fine until all of a sudden it will have no power and will spit and sputter again for a moment and then all is fine again. It has been scanned with both an OTC and a Snap ON scanner . Thanks for the help. It might be time to shoot the old horse



 
2plus2 
Member
Posts: 1072

Loc: Langley,BC
Reg: 02-03-05
09-16-17 10:49 AM - Post#2707828    
    In response to crazycoyote

If the suburban was a 99 with a 350 then there is no way it will work
The 350 has a different firing order then the 5.3
Not to mention the 350 has a distributor and the 5.3 has 8 individual ign coils
Part numbers mean jack,its what firmware is loaded onto the PCM


69 Canadian Pontiac 2+2
factory L48 350 Chev,TH350,PW,PT
99 Silverado RCLB 4.8 NV4500 14BSF 4.10's locker 6" Procomp 35 bfg m/t's 9k winch cutout flares
07 Town Car Loaded,Tinted,Getting Bagged


 
jktucker92 
Silver Supporting Member
Posts: 92
jktucker92
Reg: 02-05-17
09-18-17 06:50 AM - Post#2707997    
    In response to 2plus2

Since the PCM is the correct PN, it should work for your application with the correct program in it. However, I'm not aware of any '99 Suburban that had the 5.3L engine, since a '99 Suburban was a GMT400 truck and would have had a 5.7L gas, 7.4L gas, or 6.5L diesel engine. Yes, '99 was a transition year for the trucks, but I believe all Suburbans were GMT400's. For that reason, I don't think you can be sure what program is in the new PCM. Things can be mis-marked at a wrecking yard, and there are also rare cases where a conversion was done.
The next step would be to flash the new PCM with the correct program for your vehicle. You can either drive it to the dealer with the old PCM (assuming it will get that far) and have them flash it or find some other way to have the PCM flashed with the correct program. I believe there are some online services that can flash a PCM, but I've never used them and have no opinion on the service.



 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-20-17 07:38 AM - Post#2708224    
    In response to jktucker92

You are correct. My mistake interchange says 99-00 trucks but only 2000 Suburban. I returned to salvage yard to verify and my mistake again as the one I got came off a 2000 Suburban with a 5.3 same as my truck. Since the yard was willing to exchange it I got one from another 2000 Suburban with a 5.3 and 4wd just like my truck except Suburban. Part# 09354896 Once again no start. I will try the relearn again and see what happens. Sure seems like it should just plug and play since engine controls should be the same. I would think it should at least run. Thanks again to everyone for their help



 
wreckmech 
Member
Posts: 197

Loc: Parsippany, NJ
Reg: 10-08-02
09-20-17 05:00 PM - Post#2708298    
    In response to crazycoyote

The ECM is VIN specific. If it sees a different programmed VIN#, it assumes a theft condition, therefore no start. The VIN# relearn procedure took over an hour when I did mine. Make sure you have a battery charger hooked up when you do it.

Turn the key to the run position, no cranking. Leave it on for 25 minutes. Turn it off. Do this 3 times. Don't scrimp on the 25 minutes. If it doesn't start, do it one more time. I had to do mine the fourth time. It then started, and ran fine.



 
rockfangd 
"4th Year" Gold Supporting Member
Posts: 2215

Age: 31
Loc: Utica ny
Reg: 04-13-10
09-20-17 05:58 PM - Post#2708309    
    In response to wreckmech

Agreed.
I mentioned that because I have run into it before.
Not much is plug and play anymore.
Vin info in all modules must match otherwise it will not work

Old School GM fan FOREVER


 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-21-17 08:27 AM - Post#2708370    
    In response to wreckmech

Thanks I'll give it a try and let you know.



 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-23-17 04:54 AM - Post#2708601    
    In response to wreckmech

Thanks wreckmech It was a good try but still no start.Just an occasional kick like it may want to start. But I got that with both pcm's before trying any relearn. I went thru the 25 min sequence 5 times with no luck. Back to the drawing board.



 
wreckmech 
Member
Posts: 197

Loc: Parsippany, NJ
Reg: 10-08-02
09-26-17 03:53 PM - Post#2708953    
    In response to crazycoyote

Two things I thought of....Check the ground wire for the coils on the left side of the engine down at the bottom just above the oil pan. I had a friends Suburban that drove me crazy for a week before I found that bad ground. It would crank, but only cough once in a while....

The other thing I can think of is the fuel pressure. It should be around 55psi...

You may have multiple problems that just happen to have manifested themselves when you changed the PCM...

Good luck, and let us know.



Edited by wreckmech on 09-26-17 03:55 PM. Reason for edit: No reason given.

 
rockfangd 
"4th Year" Gold Supporting Member
Posts: 2215

Age: 31
Loc: Utica ny
Reg: 04-13-10
09-26-17 04:33 PM - Post#2708960    
    In response to wreckmech

I agree on that ground.
Sometimes they are intact and rotted.
Most of the time they are rotted apart.
Causes all kinds of issues, from no starts, to starts but runs horrible, goofy issues, you name it.
It is the engine to frame ground

Old School GM fan FOREVER


 
wreckmech 
Member
Posts: 197

Loc: Parsippany, NJ
Reg: 10-08-02
09-27-17 04:30 PM - Post#2709050    
    In response to rockfangd

There is also one that is specific for the coils on the side of the block. That is the one that drove me crazy on my friends Suburban.



 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
09-28-17 03:00 AM - Post#2709082    
    In response to wreckmech

Thanks guys, I had checked fuel pressure and regulator both are good.You are right about the havoc a ground can cause. I got tired of all the trying so I ordered a used ECM from Flashmasters in Cincinnati, Oh. For under $100 I got a used ECM flashed to my vin#. After install and a 30 min relearn it started and ran good for a short test drive. Not sure yet if it cured all the problems I was having but it seems to start alot better.I still don,t understand how some guys on you tube show a ecm change with relearn and it runs without being flashed but mine wouldn't. I'll let you know if it cured my other gremlins. I knew I shouldn't have feed it after midnight. Thanks again for all the help. What a great site .



 
wreckmech 
Member
Posts: 197

Loc: Parsippany, NJ
Reg: 10-08-02
09-28-17 05:00 AM - Post#2709090    
    In response to crazycoyote

On my 01, I used a junkyard ECM. I had to do the relearn procedure 4 times to get it to run. No issues after it relearned.

I just bought a "custom tune" from Nelson Performance. They have a page to give all the pertinent info for your truck. I plugged it in, and it started right up. It had kind of a rough idle at first, and took maybe 15 minutes of running before it smoothed out. I have had no problems with it since.

I went with a custom tune to get rid of the majority of the "torque management" that Chevy puts in to save the drivetrain. It was kind of expensive for what I got out of it, but I'm glad I did it.

I'm thinking you have something else going on with yours. Do you have access to a scanner that reads live data? That may be the only way you find out what's going on.




 
rockfangd 
"4th Year" Gold Supporting Member
Posts: 2215

Age: 31
Loc: Utica ny
Reg: 04-13-10
09-28-17 05:01 PM - Post#2709157    
    In response to wreckmech

honestly it completely varies by vehicle.
I dont think even the manufacturers know for sure.
there could be 2 of the same vehicles and neither are the same.
Happy technology

Old School GM fan FOREVER


 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
10-09-17 07:01 AM - Post#2710272    
    In response to rockfangd

So goes my luck. It seemed to run good for a few days and the right back to where I was. Hard starting, occasional stalling, spit and sputter or loss of power, the rest of the time it runs great.You just never know when it will act up. I changed fuel pump and filter since gauge didn't work anyhow. it tests good, so does fuel regulator. I have replaced MAS,TPS and coolant sensor. cleaned throttle body and K&N filter very good. I tried the computer because I thought with all the different gremlins and no codes it might be in the ECM. No such luck.



 
jktucker92 
Silver Supporting Member
Posts: 92
jktucker92
Reg: 02-05-17
10-09-17 12:25 PM - Post#2710303    
    In response to crazycoyote

Sounds like what you've done should have fixed most of the likely culprits. Three other things come to mind. If it only has issues at idle, it could be the idle air controller, which is there to maintain idle when you're stopped. If it starts with your foot slightly on the accelerator, that could be the problem. A stuck EGR valve can also cause a rough idle and no start condition. Both of those problems should not be noticeable at speed. The third issue is a bad ground wire. There's one at the top back of the motor that can be corroded and cause random electrical gremlins.



 
N8sToolz 
Very Senior Member
Posts: 2322
N8sToolz
Age: 31
Loc: N 42° 53.290' W71° 34.1...
Reg: 10-23-03
10-09-17 03:42 PM - Post#2710320    
    In response to jktucker92

Do you have any scan tool whatsoever? Any engine codes? Does it start and idle ok for a minute and then start running rough or is it rough right away. How about driving down the road is it ok at light throttle and get worse as you throttle in? Faulty oxygen sensors are pretty common.



 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
10-11-17 12:40 PM - Post#2710547    
    In response to N8sToolz

It shows no check engine. been scanned several times with both a Snap On and OTC scanners . No stored codes, It can run bad at any speed and then run just fine.So many different intermittent issues is what lead me to think it may be a faulty ECM.



 
crazycoyote 
Forum Newbie
Posts: 26

Reg: 01-10-15
10-22-17 03:08 AM - Post#2711659    
    In response to crazycoyote

Had a little time yesterday so i removed and cleaned the ground wires at rear of block and left side by oil pan. all looked fine but i gave them a good cleaning. Didn't change a thing



 
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