Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
ive got a 2010 chevy impala 3.5 pulled out of the repo line. dont know any history on it. the issue is, when the ignition switch is put into the run position, the car cranks. had an 08 that the switch was the same. same issue. when looking in the bcm, i can see where the ignition switch location is. it appears correct. there is a yellow wire that is the signal for the starter relay that comes from the pcm and it has voltage on it at all times which is the issue. from my understanding, the bcm sends a starting signal over the comm lines to the ecm which then sends the signal to the starter. starting my diagnostics at the bcm, i removed the acc wire from the ignition switch and it wouldn't crank, so im a little confused, though wondering if it is the pcm.
after looking over it, we put another computer and programmed it. still not start. after tracking down the no start issue, the low line was being pulled down by a couple modules. after finding the ones and disconnecting them, the lan came back up. the TDM was still down, found used and programmed to vehicle. learned key to TDM and the vehicle now starts and drove out of the shop. PHEW.
first thing i do with any of these auction cars or any other car lot car is check for any crazy wiring. although this car is really rough, the wiring was clean, nothing added on
Which wire did you remove from the ignition switch to get it to not crank? I like this test, just want to understand exactly what changed.
In the BCM scan data, what does the Power Mode data list have to say about the ignition switch while it's in the run position?
For testing purposes, it might be easier to disconnect the starter S-post wire and wire it to a test light. That way, you can see the light illuminate while you're testing, instead of cranking it multiple times.
there are no addons to the system, ive checked all over.
as for what wire i removed, i do not remember, i would have to go back and look. i pushed the thing back outside to make some money.
good idea about disconnecting the start wire from the starter, i should have thought of that. that would allow me to leave it in the run possition and see if i can get it to quit.
when i check all data on the scanner, it appears that when the ignition switch is in run, it is NOT asking for crank, but when twisted further into the crank position, it says crank.
