2005 Buick Century, Hard Crank No Run Condition

This 2005 Buick Century came in with the complaint that sometimes the engine would not start and using the turn signals would cause the engine to stall. It belongs to a local used car lot and they did not tell me all of this. Had to figure it out on my own over several days. They just stated that sometimes it would not start.  Well it showed up with a  dead battery so I had to recharge the battery and check for codes. There were a ton of codes stored. Most were related to poor voltage readings in various modules and a couple of VATS codes.  There were both VATS and standard keys in the ignition. I cleared out all of the codes. After the battery was up, the engine cranked and ran normally for several days. Making assumptions that they were possibly using the wrong key to start the vehicle I installed a VATS bypass chip and backed the car out of the shop and parked it. I came back to it about an hour later to move it around and it would not start. The symptoms that I now had were that the starter would begin to work and then just kick out and stop working. The dash lights would flash on and off and relays could be heard clicking in the same manner (steady pattern). I am not sure why I tried this but I pulled the headlight switch on, the clicking stopped and the engine would again start and run normally. Turn the headlights off and the engine would stall. The clicking and flashing symptoms would return. I was leaning towards a loose ground or a faulty BCM. Put the car back in the shop for the night so I could start on it first thing in the morning. Guess what back to cranking and running normally. For the next couple of days I did some research on the symptoms only to find none exactly like the symptoms I had experienced with this Buick. I did however find that there is a very common symptom of the engine stalling when the turns signals are applied. I checked for this problem and sure enough it would stall whenever I turned on either one of the turn signals. The cause for this is generally a faulty ignition switch but I wanted to do some testing just to be sure. So I went to the passenger side interior fuse block and measured the voltage on the PCM fuse with the engine running.


I compared that reading to the voltage on the Accessory Power Buss fuse and found a two volt difference.


Further monitoring of the voltage on the PCM fuse saw the voltage drop as low as 6.89 volts.


Turning the turn signals on dropped the voltage down to less than half of a volt.


I referred to a wiring diagram and found power for the PCM fuse came from the large pink wire at the ignition switch.


I saw the same general voltage fluctuations while testing on the pink wire at the ignition switch harness connector.




This article is more about how to test rather than how to change the switch out. The procedure is very similar to others that I have done in the past.

In the next picture I am pointing out that removing the two upper steering column retaining nuts will allow the column to drop down. This a makes it easier to remove the upper steering column cover without having to remove the instrument cluster trim panel that runs from one side of the dash to the other.


In the next few pictures I want to point out a few of the differences between a quality ACDelco / GM ignition switch and a cheap knockoff. I felt compelled to do this since the switch that I took out was a nearly new switch.

The two switches have blue locking bars in the harness connector. The one on the left is darker and made of a weaker plastic that is more prone to melting. The wire insulation on the left is slightly thicker but also a weaker material that again is more prone to melting. In case you did not know the one on the left is the defective switch that I removed from this vehicle and the one on the right is a new genuine ACDelco part.


The genuine ACDelco part has a higher quality electrical tape securing the harness wiring together. It also has a numbered band with a part number code on it.


Even the metal ring on the defective switch was made poorly.


The defective switch had a series of numbers stamped on the end panel in yellow ink.


Nothing wrong with that but I pointed it out since the genuine ACDelco switch did not have these numbers printed on it.


I know it is hard to tell with just pictures when one would really need to see these switches in person. I am trying to draw distinctions to the cheapness of materials that are visible externally in order to get you to think about the overall quality of parts. One other thing that I would like to point out. It is entirely possible that the person that bought and installed the failed switch may have thought that they were buying a genuine branded part. There are a lot of knock offs and counterfeit parts out there. So in addition to buying parts from a trusted brand like ACDelco you also need to be buying those parts from a trusted supplier.

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