Subject is a 2DR 2000 Blazer LS 4X4

...here's a quick fix that might save you some time and money...

Every once in a while, especially when I hopped in and threw the keys into the ignition in a rush, my truck would crank and not start. If I left it for a while and went back, it would start right up. After a few occurrences, I noticed that the security light was flashing. After a few more occurrences, I narrowed the idle time window down to 15 minutes and noticed that if you sat in the vehicle with the radio going, the accessory power would shut down after exactly 15 minutes. This was a good clue that it was ignition related.
The dealership confirmed this suspicion and quoted me upwards of $600 to replace a faulty ignition switch.

After much monkeying and researching, I have arrived at a zero-cost and permanent solution.

Once, you get the truck running, simply cut the yellow wire in the pictures below. The PCM is convinced that the ignition switch fails while you are driving. As a result, it cannot shut your vehicle down because it would be terribly unsafe.

I have not had a repeat in over a year, and it was faulting out on me with increasing frequency when I decided to take action.

The only downside, other than the obvious, is that the "security" dashlight remains illuminated after startup. Remove or disable the bulb if you prefer not to look at it.

Oh yes, if you break the plastic shroud like I did because of excessive caffeine intake, you can fix it with some epoxy reinforced with fibreglass cloth.

 

Thanks. Did your gauges ever go crazy also because of the "bad" ignition switch? I have many strange electrical issues with my 01 blazer and it wont start.

 

I didn't notice anything else. My speedometer drops out every once and a while for a few seconds, but that started happening since. Best of Luck

 

thanks. this has happened to me recently. So the part at fault is the ignition switch you say, is that the entire key cylinder?

sorry, i dont exactly know what the ignition switch is.

 

Sounds like a viable solution for a pass-lock failure on the 98+ trucks, but might not work for every case that might illuminate the 'security' light. Also, what happens if you reset the PCM (disconnect battery, etc)? You might want to install a switch on that wire in case you have to reconnect it, start it, and then disconnect it while running sometime in the future.

For those that may be in a similar situation, this wire is accessible at the large connector under the steering column above the lower hush panel (cavity D3 - magnetic rotation detection sensor signal - circuit 1836 - yellow smaller gauge wire).

For information on what the ignition switch is, where it is, and what typically goes wrong with it check the links in my signature. The Tech Article (DIY) section has a few threads on the subject.

 

ok, i have a similar problem. tonight i was driving home from my buddy's house. i got onto the main road from his place and my security light popped on while i was driving. a week ago i had the no start issue and it went away after 20 minutes.

is this directly related to the ignition?

 

It's been a while since I had any of these issues, but I do remember that the security light would come on intermittently while I was driving. I remember waiting for it to go out one day before I shut the truck down because I was afraid of it not starting again for at least 15 minutes if I shut it off with the light on. Let me know if you try this and it works. After living with the occasional problem (initially it was once about every 6 months) I got motivated enough to try and fix when it was happening almost every time I went to start it. It took about two years of daily driving to get to that point.

It may not sound like a serious issue, but when your truck wont start and you NEED to be somewhere, 15 minutes or 1/2 an hour will ruin your day.

If you do cut the wire Mr. Topper, the underdash switch sounds like a good idea, but I know where you live and an illuminated security light above the speedometer might save your butt from an attempted car jacking. A couple of these in the passenger seat might too though....



Edit - if you are concerned about just simply cutting the wire and dissabling the Passlock system, here are a couple of different solutions that I've used.

If you remove the induction coil (heating element) out of the removable bit of your cigarette lighter and then bridge the circuit from the centre post to the outside contact housing with some solder you will effectively turn this assembly into a concealed switch. (be sure to cut the power and ground leads to the lighter assembly first)

This concealed switch can then be wired in series with the yellow wire described in the above posts. This will complete the key detection circuit (yellow wire) of the PassLock system in a similar fashion to inserting the key into the tumbler cylinder, but by pushing in the cigarette lighter instead.

When parked, just pull out the cigarette lighter - no one will be starting your truck until they push in the cigarette lighter.

You can also run the starter circuit wire under the column through your switch - turn the key but no starter unless the lighter is pushed in.

 

see, i have a nice flashing blue light on my dash for my security system so i'm not worried about getting jacked. thank you for your help, i'll look into it tomorrow in my auto class. automotive electronics and this will be a perfect thing to talk about haha... thanks for your help with it

 

this is frustrating, just happened to me again

about -25*C and i thought it was plugged in all night, but the breaker in the house blew and i tried to start it with my remote starter. I think my redtop may be on its way out also, it cranked reeeaaaly slow. it tried twice, then i opend the door and seen my security light was flashing. it seems to do it when i use my remote starter.....but i also know that my ignition switch has had hiccups in the past (didnt let me shut off engine)

what exactly is the problem? sure you can replace the entire assembly, but there has to be more detail than that?

 

Oh believe me, I know EXACTLY how frustrating it is; that's why I tolerate the yellow security light! It's been a while since I did the research, but if memory serves there are magnetic, reed type, proximity sensors above the lock cylinder that detect the presence of a key. As they age, I believe they stick; and yes, it's always when you're in a hurry! lol Anyway I put in pictures of the wire to cut once you get it running, I don't know what else I can give you for details. Update the thread if it works out for you though - it's worked great for me!