starting issues

[99_2door]

99 with 80k miles........right after i bought it a couple months ago, it started having starting issues. every couple days it would randomly not start. it would fire and then shut off immediately. ended up being the passlock sensor and after replacing that everything has been fine. well fast forward to now, the truck has not been started in almost a month because i've been doing a bunch of work to it. the battery was out and when i put it back in, it started up with the problem again. would fire and then shut off. i let it sit over night and the next morning it started and drove great. well the last week it sat while i did some more work and tonight when i went to start it, same thing. wtf is going on!!!! i guess its a possibility that the sensor is bad again but its been fine for months and has only started acting up after sitting. i dont think any work i've done could have messed it up but i'll list it just in case anyone has any ideas....

new fender, grille surround, front and rear bumpers, overhead console, bumper brackets. i did do some wiring (overhead console and new headlights).

anyone have any ideas? has a full tank of gas, newer plugs, filter, etc all from a tune up so i'm leaning back towards the passlock sensor as the symptoms are the same as the original problem. anything i can do to test this short of going to the dealer?

thanks everyone!!!

 

[MetalStorm]

Dude I am in the midst of dealin with the same type of issue on my 99 4 door, 169,000 miles and it is incredibly frustrating. You'll see these threads pop up once in a while and there always seems to be different solutions for each of them. The part that sucks is that the truck will run absolutely fine, its just an intermittent starting problem.

I originally started with fuel delivery to resolve the problem. Fuel pressure is great on mine, changed the fuel filter, and the all popular fuel pressure regulator was changed {kinda a ***** to get to}. Truck ran great, started no problem, then a short time later the problem started again. Mind you it never threw any codes.

Recently did a custom {aka homemade} cold air intake with a K&N, plugs, wires, coil, cap, rotor, SeaFoam, lots of fuel injector cleaner, and 93 octane, and it has started every time since doing that stuff last week.

If, for instance, I have the same problem again I am not sure what direction to go in with this. I have dealt with fuel/air delivery, and ignition components. Again, no codes. If there were that would give me something to work with, but it really is a guessing game.

 

[99_2door]

steve have you replaced the passlock sensor or had anyone suggest it?
when i initially had problems i couldnt figure it out so i took it to the dealer. they determined it to be a passlock sensor and after replacing it everything has been fine up until now. apparently there have been issues with this sensor and i read somewhere that it corrodes and it can be taken apart and cleaned but the dealer fix is just a swap. what i dont get about my situation is about 2 months ago the battery died (it was old) and i put a new one in, everything cool. now i unhook battery for a month while i do some other work and the starting issues are back. there is nothing else i touched on the truck that could have possibly tripped the passlock.




---------- Post added at 09:02 AM ---------- Previous post was at 09:01 AM ----------

*UPDATE* truck started right up this morning no problems. but, the "security" light on the dash was on. never seen that one before.............does this point even more towards the passlock being bad???

 

[MetalStorm]

2 things....

1. what is the passlock sensor and where is it?

2. now that you mention the security dash light, i remember mine did come on once or twice and then it went away. don't remember how i got it to turn off though.

OK I just found a thread on Chevrolet Forum: http://www.chevroletforum.com/forum/showthread.php?t=21877.

I will try to attack this today.

 

[99_2door]

passlock sensor is in the steering column. i believe its part of or inside the ignition switch but i dont know for sure as i took it to the dealer when it got replaced. there seems to be some disagreement about the fix in that link you posted and others i've seen......some guys say the sensor cant go bad? others say it gets burned? i'm thinking about taking it in again (they better warranty this job for as much as they charged!!!!). my girlfriend daily drives this truck and i cant afford to have it torn apart in my driveway while i sort it out.
steve did you notice where the mobile audio guy said he could bypass it for $40? if that wouldnt present any other problems down the road i might check into that because i have been meaning to get a good security system put in the tahoe anyway since i bought it. let me know what you find out today and i'll update you with what the dealer finds.

 

[MetalStorm]

I didn't have a chance to tear my column apart today, but i will definitely keep you informed as to what I find this week. I would have no problem bypassing the security as I have never even had the remote for it.

 

[99_2door]

truck did not make it in to the dealer today. started great all day with no symptoms. pretty hard to bring it in while its starting fine.....you get some funny looks from service advisers!! i also just have the key, no lock/unlock fob, and i've been looking into a quality aftermarket alarm system. as long as i dont have any starting issues in the next few days, i'll prob stop by a few shops and get quotes for a new system and passlock bypass.

btw steve, are you going to do what was suggested in that thread about cleaning the contact points? might be worth pulling it to see if they are indeed burned.

 

[faze]

If you can bypass it...I'd suggest, if it's not too much of a pita, to do it after your next stall, drive it for a week and see if the problem crops up again.

what is the passlock sensor for?

 

[99_2door]

i think its only purpose is when you go to start your car, it reads the resistance off the key and if it doesnt match up with what the computer expects it prevents the engine from running for at least 10 min.

 

[MetalStorm]

I haven't had any starting issues since the work I did that I mentioned earlier. Its been about a week now. The first thing I will do is pull the ignition switch and passlock sensor the next time it happens.

 

[MetalStorm]

so I guess I spoke too soon. I went about a week and a half with no starting problems. Then today it wouldn't start. So I turned the key to the on position and left it there. The "security" light went off after 4 minutes, and I turned the key and it started right up. So what do you think? Passlock sensor? Ignition switch?

 

[99yuko]

Ok, my 99 Denali is going threw a similar deal. 2 weeks ago today I replaced the fuel pump. The reason is when I would fill my take, the fuel would spill out and all over the top of the tank. Once I had the take out I noticed the retainer nut thingy was completely loose(off) and the whole thing was actually just bobbing there. I installed my new pump, harness, gasket... (after I got the retainer nut on all the way I bent the tabs out to futher retain it). I filled the tank up, it worked, the gauge worked all was good.

Fast forward to today and 600 miles away from home. As I tried to start my Yukon, it started ran for no more than 1 second then it stopped. It did that the 6-10 times that I tried. So my daughter and I had to catch the shuttle from the Mcdonald house to the hospital.(son has leukemia, last round of chemo, is in remission) I left hospital and walked to a fuel station and got a 2 gallon gas can and walked back to truck. It started right away. I returned to the station and filled the truck up, it only took 15.9 gallons??? I believe its a 30gallon tank. My fuel level gauge works intermitenly so I had no way of telling.

I am torn, i have heard that it could be my new pump, or the passlock, sounds like the passlock to me. I have issues with the steering column(replaced the tie-rods, pitman, idler arms, upper ball joints, swaped steering gear, and still have a shit load of free play in the wheel and it makes noises when i turn it.

Any Ideas.

 

[Bitsman]

My story.. hope it helps

I know I am a little late to this conversation.. But here is my Story..
99 Tahoe.. 154,000 miles.. 4 dr, 4x4.. 5.7 liter... Given to me by my oldest sister Boyfriend. all it needed was a set of tires.. Traded my old Caravan to a local tire shop for a set of what look like brand new take-offs.. Ran great for about 2 months.. Then the problems started... Would not start so i replaced the Battery.. began starting fine and all was well for about a month... Then it just stop starting again... Sometimes it would jump.. other times it would not... Sometimes it would just start as it was supposed to.. Other times just one click when I turned the key... Replaced the Starter.. Everything was fine again for about a week... then went back to the one click when you turn the key... Took Starter back off and to get tested.. tested fine.. reinstalled starter and it started right up and was good for about a week.. Then no start again.. Started checking wires around ignition switch.. sometimes they would test good then other times they would seem to test bad... Figured best to replace ignition just to be safe... After replacing ignition.. still would not start... Just one click when key was turned to start.... That was last night... Did some more looking online and thought it might be a battery cable problem now.. spent this am cleaning both pos and neg cables with solvent and wire brush this am... put it all back together and it started right up... Of course it has only been about 7 hours so far so I am still not sure if this is an actual fix yet... Moral of my story.. If you are having similar troubles... Really clean your battery cables first of all....

 

[MetalStorm]

Sounds like your problem might be of a different type. The issue we are having the motor would crank but would not get any fuel.

I did a little networking, and through a friend of a friend I obtained from GM a step by step and diagram of the passlock sensor replacement and PCM re-learn.

If anyone is interested PM me and I will email it.

 

[wpnzrule]

This may be silly, but seeing that the pass lock reads the resistance on the key. What are the chances that its not the sensor but the key?

 

[MetalStorm]

Thats a good question and I never really thought of that. But I could see a sensor or ignition switch going bad before a key would. That is, if a key CAN go bad. I'll look into that.

 

[TheBeast99]

this is definitely something i'm gonna get ripped out of my truck when i get the spare chance. i mean really, if the theives wanna get my truck, they'll make sure they get it - even if it's with a flatbed! lol
so screw my key not being the right resistance according to the computer. if i want to start my truck, no damn key sensor is gonna stop me!

 

[MetalStorm]

So this week has been a disaster trying to get the hoe started. Everyday I had at least one difficult time starting it, and I even had to get a ride home from work one day.

Met a guy through a friend of a friend of a friend, who was a GM mechanic for 30 years. He came over and hooked up his GM scan tool and found a "communication error" between the Theft Deterrent Module and the PCM. This module located under the dash has 2 power leads going to it from the passlock sensor. They get their power from the # 4 and # 21 fuse located inside the driver's door. This module is also grounded in 2 places, 1 on the engine block behind the alternator, and 1 deep in the rear of the block down by the firewall. All of my connections seemed to be good. We cleaned them up anyway and haven't been able to reproduce the problem since then. The strange thing is the Theft Deterrent Module or PCM have not saved any trouble codes in their histories. Even he was confused as to why we got that error, but there is no code stored.

I also cut a new key for the hell of it last week but that didn't prevent the problem from occurring during the week.

So since this past week I haven't really done anything other than the ole "tap test", and yank on some wires and connectors. I have my scan tool hooked up so now every time I start the truck, since it has been an intermittent problem, hopefully I will catch it throwing a code and try to narrow this down more.

BTW.....i was told bypassing the theft deterrent system is not an option, as it may throw codes cutting power to the fuel pump.

 

[99_2door]

new development on mine..............truck was at the dealer for two days. they say the passlock sensor is actually fine but the ignition module (i think thats what they said?) is throwing codes and it needs to be replaced. they quoted $280 just for parts!!! damn it. i really need to find a way to bypass all this BS and just run an aftermarket theft system.

 

[MetalStorm]

yeah that would be ideal, but i think there are about 5 or 6 different modules in out trucks that all communicate with the PCM. So I'm not sure what effect, if any, that would have if you bypass it.