I took my 06 TB to a chevy dealer and they did a diagnostic scan and told me I needed a new ecm. I put a new one in and it won't start it just cranks. I did the security relearn like it said but still nothing. Anybody have a clue what's wrong?
New ecm. but won't start
- Thread starter DerrickJR918
- Start date
Chickenhawk
Member
- Dec 6, 2011
- 782
Take it back to the dealer. They are the ones who misdiagnosed the problem. If they are the ones who installed a new PCM, then it is their responsibility to fix it correctly.
Or did they just tell you the codes that indicated something was wrong with the PCM signals, and you assumed you needed a new PCM on your own.
Two things to ALWAYS understand about trouble codes:
#1 - Trouble codes indicate SYMPTOMS, not problems. For example, if you oxygen sensor is reading too low or too high on certain parameters, it is not indicating a problem with the sensor.
#2 - People think trouble codes will tell them about mechanical issues. They don't. They only indicate issues that have to do with emissions. Your starter or starter relay could be toast; your engine on the verge of putting a rod through the block; your catalytic converter almost completely plugged; and your alternator ready to give up the ghost - and you will not get one single "trouble code."
In all the years I have been on various forums, I have never heard of a single documented situation where a PCM went bad and needed replacing.
However, I can think of LOTS of reasons why a TB might not start.
Please let us know more about the conditions, symptoms and any engine codes, and we can help you diagnose better.
Or did they just tell you the codes that indicated something was wrong with the PCM signals, and you assumed you needed a new PCM on your own.
Two things to ALWAYS understand about trouble codes:
#1 - Trouble codes indicate SYMPTOMS, not problems. For example, if you oxygen sensor is reading too low or too high on certain parameters, it is not indicating a problem with the sensor.
#2 - People think trouble codes will tell them about mechanical issues. They don't. They only indicate issues that have to do with emissions. Your starter or starter relay could be toast; your engine on the verge of putting a rod through the block; your catalytic converter almost completely plugged; and your alternator ready to give up the ghost - and you will not get one single "trouble code."
In all the years I have been on various forums, I have never heard of a single documented situation where a PCM went bad and needed replacing.
However, I can think of LOTS of reasons why a TB might not start.
Please let us know more about the conditions, symptoms and any engine codes, and we can help you diagnose better.
I took it in because it wouldn't start. I turn the key on and all the dash components worked but try to start it and nothing happens. The dash and radio turned off like the signal to start was sent but no crank. That's when I took it to chevy and they said the ecm wasn't responding. Replaced the ecm myself and now it cranks but won't start. The ecm came pre-programmed and with instructions to relearn the theft deterrent and also said the crankshaft position sensor would have to be relearn. The vehicle was running great until the non start happened. I don't have the $ to take it back to dealership right now
Mooseman
Moderator
If it cranks, the relearn worked. Do you also hear the fuel pump prime when you just turn on the ignition? Where did you get the PCM? Was it programmed for the right year? Check all the fuses and relays. Recheck the connectors.
Although rare, PCM failures do happen. I've seen one here for sure, possibly two.
Although rare, PCM failures do happen. I've seen one here for sure, possibly two.
Paul Bell
Member
- Aug 16, 2014
- 460
I bought a replacement PCM for my truck. Without a re-learn, it WILL crank then seem to catch just for a moment but no more. The PCM will not prevent the starter from spinning the engine. This is because some trouble codes are set during a crank/no start situation. EG: No start spinning for eight seconds will set some codes-such as no crank signal.
Derrick, welcome to GMTNation!
As you say it's now cranking but not starting, the re-learn process may not have worked (it might take a few tries to get it to work), see if there's any codes set. I have this one: http://www.autozone.com/test-scan-a...ketscan-code-reader/603853_0_0/?checkfit=true
Derrick, welcome to GMTNation!
As you say it's now cranking but not starting, the re-learn process may not have worked (it might take a few tries to get it to work), see if there's any codes set. I have this one: http://www.autozone.com/test-scan-a...ketscan-code-reader/603853_0_0/?checkfit=true
Mooseman
Moderator
Ok finally got a code reader but it won't link so I can't get any codes. Any ideas?
Yea it was programed with year, vin, and mileage
(Posts merged. Please use the edit button. Mooseman)
Yea it was programed with year, vin, and mileage
(Posts merged. Please use the edit button. Mooseman)
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Mooseman
Moderator
All the fuses are good
I'm going to try the relearn again
Just did the relearn and it started! Thanks you everyone that helped and gave advice
I'm going to try the relearn again
Just did the relearn and it started! Thanks you everyone that helped and gave advice
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Yea it's on and the reader I have isn't working right so I'm taking it to a buddy to have it checked. If I had to guess it's probably the crankshaft position sensor
Mooseman
Moderator
It will be a code for cam/crank correlation error, which means you need a CASE relearn, which you already knew. You can run it like this indefinitely or until you need an E-test if the light doesn't bother you. Won't affect anything.