For a year now the blazer has been difficult to start with at least 3-4 seconds of cranking. It is usually followed with what I believe is the ignition cutting out for a fraction of a second as you accelerate and maintain speed. The condition usually settles out after a few minutes. The engine was completely replaced in 2009 by pep boys after they "forgot" to put oil in it so basically all the wiring in the engine compartment could be suspect.


The other indication I have is every time the ignition cuts out causing the car to buck, the battery light will flicker on for a fraction of a second. In some cases of a series of these events I will catch the ABS light flicker on for a fraction of a second. I believe these are occurring because of the lamp test when the ignition is first turned on.


All these signs make me wonder if it is all just caused by the ignition switch, but I am just not sure where to begin. I don't just want to start throwing money at it hoping I find the culprit when it could be just a loose or dirty ground connection.


I already kind of wonder about the ignition switch however because it sounds to me like when I turn on the ignition switch sometimes I hear no noise, but when I turn off the ignition switch I hear the 2 second prime of the fuel pump. I was under the impression that it should be inversed where it primes when you turn the ignition on not off.



Any ideas?




EDIT: Forgot to mention sometimes a P0339 "Faulty crankshaft position sensor" will pop up after an event, but it does say on the code that it can be caused by low voltage which I believe is my case.

 

P0339 indicates an intermittent problem in the feed circuit to the crankshaft position sensor. The ECM 1 fuse in the underhood fuse panel feeds the ignition control module, ignition coil, and crankshaft position sensor, through a pink wire. If that circuit loses voltage intermittently, only the crankshaft position sensor will set the code, NOT the ignition. As intermittent as you say that it's happening, you might want to rig up a temporary pilot light to the pink wire at any one of those components. Any auto parts store will have a socket for a #194 bulb. It has two pigtail wires attached to it. Lay the socket in the console, etc, and ground one of the wires. Run the other wire to the pink wire, close to the crank sensor would be best. If the light blinks when it acts up, you know you're on the right track.

 

I have a 96 blazer 2WD that has similar problem. It starts great and runs great but has developed a weird problem I would describe like this. I may be going across town 30-40 MPH, or accelerating onto an on ramp when it is like I had turned the engine OFF for an instant and back ON. There is just enough time for me to look at the instruments to see the ABS light simultaneously with the Check Engine light come on. These things happen exactly at the same time then go OFF and no codes are ever set. To my understanding there is no one sensor that could make this exact thing happen. It has to be some electrical intermittent connection. I have so far moved the wire harness around under the hood and dash plus jiggling the ignition key with no problem showing up. And it has never happened when the vehicle is in park, running even revving the engine. It can happen at any time driving during coasting, decelerating or accelerating. It has only done a 2 times repeat of the problem once and normally it will happen maybe once a week. I have read many posts about similar but none seem to meet all of the exact happening at once. If the engine did not do that momentary jerk, I would not notice the lights coning on because it like it didn't happen and then back to a truck that runs good. I figure I will look even closer at the wire harness and all grounds.
This is my second 96 Blazer so I have seen many of the things that can happen but so far this is the hardest yet.

 

I would suggest doing the same thing described in post #2 above, (194 socket and a bulb).

 

Captain Hook! Hello! How great to see a post from you! The man that got me started in diagnostics years ago after the patience to help me with an engine swap.

 

The "Captain" has returned!!!!.......YEAH!!!!