HELP! Won't start...just sometimes though?!

[jarede525]

I've had problems with my truck wanting to start. It will turn over, and crank crank crank and CATCH..but die real fast.

But here's the catch, it's not every time it does that. Sometimes it'll catch and start real slowly.. and THEN sometimes it'll start just fine.



At first I thought it was a fuel pressure problem, possibly the regulator or pump. So I bought a gauge to test it with, the fuel pump runs the right pressure (55) whether it starts or doesn't start. And I took the intake cover off and looked down into the intake manifold and there were no clean spots. So a leaking regulator was out...

I finally gave in and took it to the dealership to have them try to figure it out. The guy said it was a problem with the security system. And that I needed a new ignition lock cylinder housing w/passlock sensor, and a new lock cylinder, and for him to recode it. ($600 worth of work...)



Has anyone had this problem?!? It's a 5.7 vortec. 1998. Please I'm out of ideas!!

I don't know what to do and I need this truck to get me to work and back everyday...

 

[JonZ71]

Kinda sounds like the issue. You can see how much it'd be for them to turn the vats off....

 

[jarede525]

You can see how much it'd be for them to turn the vats off....

What is that?

and if it was the issue, shouldn't the security light start flashing when it doesn't start? Because it doesn't..

 

[mattillac]

The light may flash momentarily and then remain on steady. The light may also stay solid(no flash).

If the passlock was the only issue then the engine should still crank strong as if there was no problem and the engine should start and stall after approx 2 seconds. Maybe the entire cylinder assemble is going kaput and that might explain a slow sluggish crank? That might mean replacing the parts and not just tuning out the passlock might be best.

The passlock can be turned off at the PCM(tuned out) but I don't think a GM dealer would do that, they would rather fix it. Jet performance has a computer program which will supposedly allow you to turn it off(besides engine tuning)but it may be like 5 or 6 hundred for the setup IIRC. Some performance tune companies will also tune out the problem from what I read on these forums, maybe a mail order tune even.

You could buy the new ignition parts and install them yourself(avoid labor)and there is a relearn procedure that will take 30 minutes for the DIYer to reprogram the new parts. Might be tricky disassembling the column though? Looks like GM parts giant list the cylinder and the housing...for about 140.00 each.

If only the passlock parts are defective you may be able to cut the passlock data circuit under the column and temporarily eliminate the issue, trick is the data wire must be cut while the engine is running so that the system will operate under failed enabled mode and ignore the passlock sensor in the column(until power is removed from vehicle)see here: http://www.gmupfitter.com/publicat/bull/bull26.pdf.

Trust the dealers diagnosis ? Is there a remote start on this truck, they usually require passlock wiring/interface.

If the security light never illuminates we could perform a bulb circuit check which would involve disconnecting the theft deterrent module (under the radio area) and grounding a specific wire at the plug/harness, then go from there.

 

[sewlow]

Never knew about this security feature. Good info. Repped.

 

[jarede525]

The light may flash momentarily and then remain on steady. The light may also stay solid(no flash).

If the passlock was the only issue then the engine should still crank strong as if there was no problem and the engine should start and stall after approx 2 seconds. Maybe the entire cylinder assemble is going kaput and that might explain a slow sluggish crank? That might mean replacing the parts and not just tuning out the passlock might be best.

The passlock can be turned off at the PCM(tuned out) but I don't think a GM dealer would do that, they would rather fix it. Jet performance has a computer program which will supposedly allow you to turn it off(besides engine tuning)but it may be like 5 or 6 hundred for the setup IIRC. Some performance tune companies will also tune out the problem from what I read on these forums, maybe a mail order tune even.

You could buy the new ignition parts and install them yourself(avoid labor)and there is a relearn procedure that will take 30 minutes for the DIYer to reprogram the new parts. Might be tricky disassembling the column though? Looks like GM parts giant list the cylinder and the housing...for about 140.00 each.

If only the passlock parts are defective you may be able to cut the passlock data circuit under the column and temporarily eliminate the issue, trick is the data wire must be cut while the engine is running so that the system will operate under failed enabled mode and ignore the passlock sensor in the column(until power is removed from vehicle)see here: http://www.gmupfitter.com/publicat/bull/bull26.pdf.

Trust the dealers diagnosis ? Is there a remote start on this truck, they usually require passlock wiring/interface.

If the security light never illuminates we could perform a bulb circuit check which would involve disconnecting the theft deterrent module (under the radio area) and grounding a specific wire at the plug/harness, then go from there.

So what do you suggest I do?

Should I have the dealer replace everything and pay for labor?

Should I replace everything myself?

Should I disconnect passlock?

Oh and I don't have remote start. I don't even have wireless unlock remote..
Too many options, and electrical isn't my forte...

 

[frito-bandito]

Imo, I would check around and see if there is a shop around (not a dealer) that would possibly diable the security system for you. The main concern with having the stealership replace the parts, is that who knows how long you have until it acts up again. As for disabling it yourself, I having no experience in it, would not attempt this, I've seen too many vehicles that turn into electrical nightmares because someone tried to bypass the security system. But with all that being said, I hope everything works out good with it, there ain't nothing worse than feeling like your DD is unreliable .

 

[jarede525]

Does anyone know of any sure-fire way to make sure that it's the passlock system? I don't wanna dish out $600 for something that's not broken...

The shops around here don't have very good reputations from what I've heard... and I don't really want to take it somewhere that has little, to no experience with something like this... If you know what I mean.

 

[mattillac]

Does anyone know of any sure-fire way to make sure that it's the passlock system?....

Considering the dealer told you the passlock was the cause I would guess they used a techII scanner or similar to communicate with the theft deterrent module and diagnose it that way. If we don't have a techII then we would need to observe the symptoms. From my experiences the security light will normally illuminate momentarily after the key is rotated from the off position to the run position(bulb check?), when the key is rotated to the start position and the engine starts but then abruptly stalls after 2 to 3 seconds then the security light should be observed, if it is solid or flashing that is almost certainly passlock that is activating thus disabling the injectors. We are talking about the light in the upper right hand corner of the instrument cluster that reads security in orange letters, also referred to as security telltale.

PASSLOCK REPROGRAMMING AUTO LEARN

IMPORTANT: If a new vehicle/powertrain control module (VCM/PCM) is being installed for the first the manufacturing enable bit will be set and the auto learn procedure may not be necessary.

The following procedure allows for anyone to reprogram the EVO/PASSLOCK module learned data code with any tools, other than the scan tool, when any of the following parts are replaced:

The EVO/PASSLOCK module
The PASSLOCK sensor
The VCM/PCM

The EVO/PASSLOCK module will set the DTC B3031 in the learn mode when entering the reprogramming procedure.

IMPORTANT: Erase the PASSLOCK related Diagnostic Trouble Codes (DTCs) that are stored in the VCM/PCM.

The following is the Auto Learn Procedure:

1. Insure the ignition key is in the ON position.
2. Clear all EVO/PASSLOCK module and VCM/PCM DTCs.
3. Momentarily rotate the ignition key to the CRANK position (Do NOT start the vehicle), then release it to the RUN position (Do NOT key OFF in the process).
4. Wait 10 minutes . Observe the SECURITY indicator. Refer to the following list for the appropriate responses:

-If the PASSLOCK sensor was replaced the SECURITY indicator will flash for the 10 minutes duration.
-If the EVO/PASSLOCK module was replaced, the SECURITY indicator will flash for a few seconds and then remain ON for the remainder of the 10 minutes duration.
-If the VCM/PCM was replaced with a new programmed VCM/PCM and connected to the vehicle for the first time, the vehicle will start and this procedure may not be necessary.
-If the replacement VCM/PCM was connected to any vehicle at any other time, even momentarily, the SECURITY indicator will flash for a few seconds and then remain ON for the 10 minutes duration.

5. The SECURITY indicator will transition from flashing to ON briefly to OFF after 10 minutes if remaining in the ignition ON position.
6. Turn the ignition switch to the OFF position and wait for 10 seconds .
7. Repeat steps 3-6 two more times. The new security code is ready to be communicated among the PASSLOCK sensor, EVO/PASSLOCK module and VCM/PCM. The new password is learned on the next ignition lock cylinder cycle from OFF to CRANK to ON (start attempt).

Most people would probably prefer to tune the passlock out/off. For longevity and simplicity that would probably be the best route IMO, you would lose the security feature and diagnosing a no start condition in the future would probably be easier, such as if the ignition cylinder was still causing other electrical issues(no start etc).

If you use the vehicle as a daily driver then maybe you don't want to tinker, otherwise if you have the time and the patience, while the truck is running, I would install the on/off switch per the Upfitter instructions mentioned before. What that switch will allow you to do is deactivate(isolate)the key portion of the passlock, so that for the short term you hopefully wouldn't have the start and stall condition. Read the directions, if you don't feel comfortable doing it then you probably shouldn't, and as the directions state if power is ever removed from the vehicle(dead batt etc)the circuit would need to be reactivated(switched closed)and all the components(hall effect sensor/TDM/PCM/wiring)would need to be functioning correctly in order to restart the engine after battery power was restored.

Just so others know, the passlock we are talking is 98 and newer, other users have actually mistakenly placed 97 columns in a 98 and found out the hard way that they had to either tune out the passlock from the 98 PCM or find the correct 98 or later column with the correct wiring and sensors.

I remember reading that........Jet Performance Dynamic Spectrum Tuner Programmer Part #: 14005 499.99 http://www.jetchip.com/Shop/shopdisplayproducts.asp?sppp=10&catID=1 will turn off the security feature in the PCM if you wanted. I would verify with their tech people that it would do what I wanted before purchasing one.

http://www.gmpartsgiant.com/ has some nice parts diagrams for the column(#15/19)and theft deterrent module(#10), for reference, parts pricing etc.

Hope that isn't too much info.

Good luck.

 

[frito-bandito]

Great reply man!