1998 K1500 5.7 starts then immediately dies

[JimRMac]

My Suburban starts then immediately dies. Fuel pressure is good and I can hear the pump run when ignition is turned on. I bypassed the Passlock system about 3 years ago using the capacitor spliced into the wiring in the steering column method and had no issues afterwards. The security light is not flashing and it's throwing no codes. I pulled the steering column cover off and checked my splice and everything still looked ok. Could the capacitor have gone bad? Would an ignition component problem (coil, rotor, ICM, etc.) even allow it to fire at all? Not sure where to start checking first. Thanks for any help.

 

[df2x4]

You mean resistor? I'm not aware of any Passlock bypass method involving a capacitor.

Either way though, yes it's entirely possible that the components have drifted out of spec. This is why I always recommend that anyone trying to disable Passlock do it in the PCM tune. It prevents the PCM from even looking for a signal from the Passlock module and is the only 100% sure way to permanently disable that system. Everything else is just fooling the system into thinking it's working properly.

 

[JimRMac]

You mean resistor? I'm not aware of any Passlock bypass method involving a capacitor.

Either way though, yes it's entirely possible that the components have drifted out of spec. This is why I always recommend that anyone trying to disable Passlock do it in the PCM tune. It prevents the PCM from even looking for a signal from the Passlock module and is the only 100% sure way to permanently disable that system. Everything else is just fooling the system into thinking it's working properly.

Yes, I did mean resistor. I'll Try a new resistor and see if that fixes is it. I assume to do the PCM method, the resistor could be removed, the original wires hooked back together and then go from there. Second question; how do I find out how to do the PCM tune?

 

[df2x4]

I assume to do the PCM method, the resistor could be removed, the original wires hooked back together and then go from there.

Shouldn't matter. You're programming the computer not to look for a signal from the Passlock system at all, so even if the wiring was completely gone this would work fine.

Second question; how do I find out how to do the PCM tune?

Any tuning software that's compatible with the '98+ PCMs should capable of doing this job. EFILive, HPTuners and JET DST are three that I'm aware of. If you have any shops in your area that do tuning and have access to one of those three programs they can do it for you. If not, you could buy the appropriate software and do it yourself. It's stupid easy, as simple as checking a box once everything is set up.

There are also mail order tuning businesses that could do this for you. Black Bear Performance, Wester's Garage, PCM4Less to name a few.

 

[JimRMac]

OK, thanks for the info! I'm going to replace the current resistor with another one this weekend just to make sure that's my problem and then go from there. Will update progress when I do. I did this same bypass on my 2000 C2500 7.4 about 10-12 years ago and have never had an issue. May be the difference in resistors used, I dont know.

 

[df2x4]

With the symptoms you describe, I'd be willing to bet this is a Passlock issue even if your resistor bypass isn't the problem. Could be another part of the system failing, like the module itself.

 

[someotherguy]

With the symptoms you describe, I'd be willing to bet this is a Passlock issue even if your resistor bypass isn't the problem. Could be another part of the system failing, like the module itself.

Since the entire circuit theory is based on small resistance values, it doesn't take much to cause problems. As the multiple connections in the circuit develop issues over the years, resistance increases, and "fixes" like the resistor no longer work because the overall resistance in the circuit has changed so the reading back to the TDM (theft deterrent module) is no longer what it's looking for as a "good" value to allow the truck to run.

That's why for the past few years most of us have been advocating for tuning the Passlock completely out of the PCM, because any other method will eventually end up failing again.

Richard

 

[JimRMac]

Has anyone had experience with the bypass module that Newrockies offers? Supposed to completely bypass the system without having to do the PCM reprogramming.

 

[df2x4]

Has anyone had experience with the bypass module that Newrockies offers? Supposed to completely bypass the system without having to do the PCM reprogramming.

FWIU it's basically the same thing as the resistor bypass, but in a really expensive box.

EDIT - To explain further... Their website claims that they reproduce the output signal that the Passlock module would normally send to the PCM. That means they're still "tricking" the PCM into thinking that the Passlock system is functional. If something ever fails inside that NewRockies box (or the connections between it and the PCM) the Passlock problems return.

Programming the PCM to not look for that signal is the best solution, and I'm sure you can find someone to do it for less than the $300 that the NewRockies BS costs.

 

[JimRMac]

What has me a little stumped is the bypass I did 10 years or so ago on my C2500 is still working. I bought a "kit" on ebay which was basically instructions and a resistor. The resistor, according to the info that came with it was tested to be 2,750 ohms, wattage not stated. The resistor I put in the suburban was from a pack of ten I bought on amazon, 2.2K ohms, don't remember the wattage. I'm wondering if I have a "hardier" resistor in the C2500 than in the Suburban and that's why no problems (yet). I will say that after I did the bypass on the 2500, the "security" light is always on.