plugging in scanner causes all to be fine.............................
plugging in scanner causes all to be fine............................. i bought an actron scanner today and when i plug it in i get my dash lights back....it shows no codes except that i took off the egr....well now it cranks but doesnt fire....pulled a plug and no spark..but i do have fuel pressure...hear the pump prime then cranks and cranks....no fuses blown but it wont start anyone know whats up????? thanks
Teching In
Joined: Dec 2001
Posts: 387
Likes: 0
From: Southern IN, USA
WTF do an Actron scaner, missing dash lights and a no start condition have in common?
However, I do recall reading about a Neanderthal Caveman grumbling that "Um, it difficult to cook antelope if there no spark to light fire..."
How about a bit more logical train of thought and a bit more specific explanation of the problem, the type of car, conditions leading up to the problem, etc.
Don't forget to check the nut behind the wheel...
MRK
However, I do recall reading about a Neanderthal Caveman grumbling that "Um, it difficult to cook antelope if there no spark to light fire..."
How about a bit more logical train of thought and a bit more specific explanation of the problem, the type of car, conditions leading up to the problem, etc.
Don't forget to check the nut behind the wheel...
MRK
this is an ls1 /6....i had the battery disconnected to weld up new exhaust....after finishing welding i put the cables back on battery and got in to start, turn the key and all i get is an SES light no milage shows up or anything.....read somewhere how to do a bcm scan and says maf shorted, IAC valve shorted, pcm....so i went out and bought a scanner and when i plug it in and turn the key on , now all of a sudden i get my dash lights back and milage?!?! so i read the computer and i get a po405 for egr removal /no other codes....but when i unplug the scanner tool i cant even crank it and its just like i havent pushed in the clutch.....it wouldnt be cranking if vats was acting up and i dont know where to begin to find out why its not sparking.....there is fuel at the rails.....ummm thats all i got off the top my head for now ANY IDEAS??? THANKS
It is a LS1 /6 what? Have you at least checked all the fuses in the two fuse boxes under the hood and the one on the side of the dash, that is guessing that it is an F-body.
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TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
yes ECM = PCM on our cars (we have a powertrain control module, controls engine trans etc... ECM means Engine Control Module ... valid when only the engine was computer controlled.. but w/computer controlled transmissions now it's PCM)
let's look at this logically... w/out the scanner plugged in everything's fubarred
with it plugged in it works...
I'm guessing that this scanner is supplying power through the OBDII port ... if this is the case then that means the PCM isn't getting power normally ....
not sure though...
let's look at this logically... w/out the scanner plugged in everything's fubarred
with it plugged in it works...
I'm guessing that this scanner is supplying power through the OBDII port ... if this is the case then that means the PCM isn't getting power normally ....
not sure though...
TECH Addict
Joined: Nov 2001
Posts: 2,662
Likes: 1
From: LaConner WA
ECM = Electronic control module. It's the same as PCM or VCM or ECU. I work on Caterpillar, Cummins, Detroit engines as well as Allison trannys. They each call it something differant but it's the same thing. Sorry to confuse you, sometimes I get confused myself. How about we call it the damn computer ?? 
Anyway whenever doing any welding on any computer controlled vehicle you always want to unplug the computer. I have replaced more than just a few when a customer did a little welding .
Anyway whenever doing any welding on any computer controlled vehicle you always want to unplug the computer. I have replaced more than just a few when a customer did a little welding . well when its plugged in, it sort of is back to normal just cranks no spark...the actron scanner i have doesnt use any batterys and gets its power through that obdii port...at work when pulling dents or patching a rust spot in the body we would just pull the battery and after welding the pins for dent removal it woujld be fine and did this all the time so i dont know/....
TECH Addict
Joined: Nov 2001
Posts: 2,662
Likes: 1
From: LaConner WA
Then you've been lucky. I'm not trying to tell you how to work on your own car, but the dozen or so schools I've been to ALWAYS say unplug the computer before welding or be prepared to replace it. I've seen many people weld with no problems at all without unplugging it, but have had to replace it quite a few because they didn't. It's kind of like russian roulette in that way. Maybe that's not your problem at all,I hope it's not, but from the way your describing the malfunction I'm guessing that it is.
TECH Addict
Joined: Nov 2001
Posts: 2,662
Likes: 1
From: LaConner WA
Like I said I can't KNOW that it's bad, I certainly hope that it's not, but I frequently read codes from computers that are effectively fried. Sometimes you can, sometimes you can't. There are many differant area's and circuits in a computer. It only takes one bad circuit to consider it fried even though there are thousands of others that might still be working perfectly. Many times the engine will still actually run, just not very well. They never seem to fail in the exact same way. Best of luck.
ok so it turns out when i jump 12volts to the coils , the motor fires right up. so somewhere between the pcm and the coils i have a break....but that still doesnt clear up why i need the scanner to start it!??!?
Like someone else mentioned in the thread, sounds like the scanner is looping back power somewhere via the DLC (diagnostic link connector). Truthfully, it really sounds like you have a messed up ignition switch...
