Hello guys,

Unfortunately here I am asking for some help as I have been experiencing intermittent No-Start issues on my 04 C5 Z06 for a little while now and the issue has gotten worse over time.

It all started when a long time ago while driving I noticed my security light came on and stayed on, without experiencing any symptoms, the next day the light was gone and stayed gone till now.

Fast-forward several months later and last month I offered someone a jump since their battery was dead, once I hookep up the jumper cables my car would not start. I sat there for a little while till it finally decided to start.

Seems like from that point on the car would fail to start every once in a while recurrently and progressively getting worse until yesterday it took me 1.5 hours playing with it for it to start.

Whenever the car fails to start, the "SECURITY" light blinks. There has also been a couple of times that the car starts and the "SECURITY" light stays on.

Here is what I have tried so far: I did the 30 min VATS re-learn proceedure and replaced the TDR with a new one (the old one seemed to have some discoloration at the prongs). Seemed like I had fixed the issue once I replaced the TDR but after several starts it failed once again. The current codes on the car are as follows: 10 PCM P1631 H and 40 BCM B2721 HC.

** I should also note that the car had some water leaks by the passenger door/firewall onto the floor pannel, I thought I corrected the issue. Later down the road I had my heater core go out and leak onto the passenger side as well (this was fixed by the dealer under warranty). **

Next step for me is probably going to be removing the ignition switch and doing a repair/clean up.

Please help, Im stuck and life without my car is sucking!

 

No, at this moment those are the only codes.

From what i can tell at the moment, there is no water marks on the BCM (will look closer). I have not removed it but will remove it and inspect it now.

I have used the back up key and symptoms still persist.

I have not cleaned the pellets on the keys but they dont appear dirty, will try this anyway, although im sure that is not the issue here.

What is "the sensor wire" and where is it? How do i clean it?

Thanks for the input.

 

I ran into a similar issue...notice my highlights above.

Long story short, what caused my issue was that over time the two tabs inside the key hole/tumbler became dirty from use...so it would read sometimes and other times it wouldn't.

Now...I could have cured my ills...for 0 bucks...but hey...such is life, live and learn.

Here is the fix: (BTW, I'm a 02 C5Z) Look at the front of the ignition...the silver "key hole". If you look inside you'll notice two, should be silver...won't be if they're a little dirty...areas where the system reads your key. If you see some dirt in there, lemme know. We can get you fixed for free...if thats the case.

If not...we can get you fixed too, just gonna be more time and some money.

Lemme know, pretty sure I can help you out man.

 

Ok, i will look in there after work today. Lets assume it is dirty in there what should i do? At this point ill try anything. How do you suggest i cure the issue?

Thanks for your help!

 

Thank you very much! I will try this as soon as i get the chance and report back.

 

***UPDATE*****

So I went ahead and cleaned the ignition with the electrical contact cleaner and the key to no avail. The car still wont start. I cleared the codes and they came back as P1631 HC and B2721 H.

Here is a question, I have been hearing reading that HP Tuners is able to de-activate the VATS system with a tune and therefor correct the problem. Is there any truth to that?

My next step is probably going to be attempting to clean/fix the ignition switch itself.

Any further info or ideas please dont hesitate, I need all the experience I can get at this time as I am a rookie at this.

Thanks for any further help.

 

Do the contacts in the ignition looks dirty?

Next step is to pull the ignition out if so.

 

The sensor on the ignition lock cylinder might not be reading the pellet all the time. On mine I got up one morning and tried to put the key in the ignition and it wouldn't go in so I forced it and broke it. They do wear out in time. Its not hard to get a new lock cylinder and have it replaced. Theres an easy test but you have to take apart the dash so you can get to the connector. You get a multimeter, set it to resistance and measure across the 2 wires in the connector with the key installed and turned. If you get nothing then the sensor is bad. You should have some resistance depending on what key you have.

 

I had the no start problem today thanks to all your answers I sprayed a electrical connector fast drying solution into key hole and cleaned pellet with eraser and my baby started right up also had the security light flashing while trying to start. the result a dirty pellet or ignition switch

 

****UPDATE****

So to recap i have changed the TDR, i sprayed electrical contact cleaner on my ignition key hole (even though it looked clean), i cleaned the pellet in both keys and even also inspected the clutch switch and sprayed it with contact cleaner. I also went ahead and tested the ignition switch by testing the volts with a volt meter and everything read 12.5v, the only odd thing i noticed is that it states that i should be checking "BCM 13 fuse 22" but there is no fuse on there and even on the IP legeng it shows that slot 22 is open/no fuse goes there.

I dont know what to do anymore....

PLEASE HELP.

 

Not sure I understand your approach, or the parts changing. You clearly have a code for the VATS, and the engine will not crank, as long as the key cannot be read. Possible causes:

1) Bad lock cylinder
2) Bad/dirty pellet on key
3) Bad wiring between lock cylinder and BCM
4) Bad BCM

You first need to read the resistance of the key you have, and record that value. Then, as a previous forum member suggested, you can test the restance at the lock cylinder connector....with the key installed. If you do not want to take apart the console just yet, you can also read the resistance at the BCM connector. Do you have the following:

1) DMM, and the ability to use it?
2) Service manual, or appropriate schematics for your car?

 

My car did have water leaks a while ago which i though i fixed, this was over a year ago. I guess i could inspect the BCM... How do i go about taking it off and inspecting and what am i looking for to determine if i need to either clean it or replace it?

Thanks,

Bad lock cylinder: how can i address this? I believe there is a recall for this on the car....?

Bad wiring and/or BCM: not sure about the wiring but im trying to figure out how to take off the BCM to inspect it for water damage/dirt...

Bad or dirty pellet on key: i cleaned the pellet on both of my keys and still no start. I didnt know that the resistor pellet could go bad...

At the moment i have a "Bel MERIT DM 3050" volt meter. I have never really used one but i will have to learn.

I read the resistance on my key pellet and it reads 8.1 how do i check to see if my ignition switch reads this?

 

IF YOU WOULDNT MIND I COULD ALSO CALL YOU TO GET BETTER DIRECTIONS AS TO HOW TO DO THIS. Just let me know if this is a easier route to come to a resolution...

Thanks.

 

Yeah, im not sure if i used it correctly..

I MEASURED IT AGAIN AND IT READ 3.00 so i think i have key 9.

I made a little VATS resistor bypass that measures the same values as my key... Im thinking about hooking it up to my ignition switch to try to permanently disable the VATS..

 

So here is what I did:

I used my volt meter and set it to 20K (OMHs) it read my key value as 2.96-3.1. I then created a resistor with as close of a value that i could come up with (2.86-3.0). I then spliced the 2 white wires (inside black jacket) that go from the ignition switch to the conector where it conects and then turns into a white/purple and black/white wires. I conected my resistors to the 2 ends of the white wires to make a loop and then conected that to the conector that went to the white/purple and black/white wires. I tried to start the car and nothing.

On a side note: I tried to get a reading off of the spliced ends after I hooked up the resistor bypass pack to the 2 white wires and hooked it up to the conector and I was not able to get a reading, I dont understand.

I am lost at this point.

I am about to try to take out the BCM and inspected but i am not sure how to remove the BCM, all I know is I should disconect the battery.

 

I'm not in a position to give you a call right now, but you need to step back, and stop going for the easy fix. Hacking up the wiring was unnecessary. All you needed to do, was read the resistance off the lock cylinder connector with the key in. If it was good, you plug it back in, and move on to reading at the BCM connector.

 

When my Zee went through the same issue - no starts with a blinking Security light - I measured the key pellet and it measured fine. Also tired the other key which sits in a box, and it wouldn't work either.

Then I looked carefully at the metal ridge on the pellet and it looked kind of grey and tarnished. Used a soft pencil eraser on the metal strip on the pellet to get it nice an shiny. That solved all the starting problems for me. Still worth a try. Not sure your fancy wire operation with a simulated key pellet resistance was a valid test or not. Hard to say without digging into wiring schematics, etc.

If the Security light blinks after the key is turned to the ON position, the BCM is not reading it for some reason.

 

I appreciate your input, i assure you, i do. But im not going for "the easy fix" im going with whatever works and gets my car started and working as it is my daily driver. I believe i asked before i did that how to read the resistance off the lock cylinder connector with the key in and also how to read at the BCM conector. Unfortunately i have yet to receive an answer/easy to follow directions.

 

Reading at the lock cylinder connector, just involves touching the meter leads to the contacts on the connector...with the key in. You should read the same resistance as the key. You never did provide an answer, as to whether you have a service manual.....

 

****UPDATE/PROBLEM SOLVED****
===============================

So first off thanks a lot to everyone that threw their input out there while i was trying to figure this thing out but a SPECIAL THANKS GO TO 8VETTE7 FOR GOING ABOVE AND BEYOND TO HELP. Thank you so much and like I said to you before, if there is ever a way I can help you please let me know as it would be my pleasure.

Well, so here it is...

After much troubleshooting it came down to having a battery on its way out while at the same time a bad ignition switch. I also cleaned the conectors at the BCM (that might have helped too).

Again much thanks to everyone!