• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

88gmctruck's 1999 K2500 L65 cranks but doesn't start.

The procedure to do if you don't have a scanner to clear any DTC codes is the 30-min passlock relearn.

30 Minute Learn Procedure (requires no tools)
1) Turn ON the ignition, with the engine OFF.
2) Attempt to start the engine, then release the key to ON. (engine will not start)
3) Observe the Security telltale, after approximately 10 minutes the telltale will turn OFF.
4) Turn OFF the ignition, and wait 5 seconds.
5) Repeat setps 1 through 4 two more times for a total of 3 cycles (30 minutes). The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

I was attempting a relearn on it, however the security light never went out, even after 20 mins or so, which leads me to believe that the ignition sensor is causing the problem and i'm just going to disable it instead.
 
Dave:

Can you get access to a tech II scanner or a scanner that has access to serial 2 data?

This will pull any fault codes related to the Passlock II system and will probably tell you if it's a module fail, hal sensor fail, etc.

If you plan on keeping an OBDII 6.5 and don't want to spend a lot of dough, I recommend you buy carcode.

It's not the most user freindly software out there, but it will pull serial 2 data and display it.

Plus, the first time you can set pump timing and tdco without bothering with a shop (IE: Tech II) it will have paid for itself.

But like I said, it can be a beotch to learn and use....
 
Well, I tested and re-installed the glowplugs. All heated up to a glowing tip within 5 seconds.

I then modified the Passlock system. I cut the yellow wire and installed a 3,700OHM resistor on the module side, and connected it to the black wire. I than began the 30-miniute passlock relearn and after the first 10-min cycle the security light is still on, when it is supposed to turn off. I'm going to town to get a OBD scanner from the parts store. I'm about to get angry at this thing. *rages*
 
83GMCK2500 said:
I see it. So how can we verify that the FS is functioning properly?
Click to expand...

This isnt your issue most likely, but you can measure the resistance across the two PMD harness wires that go to the FS and there should be 0.4 ohms through the windings of it.

If you know the PMD is outputting an inject signal, youve checked everything else, like ESO, and it isnt injecting fuel thats when you might assume the FS isnt working. With the PMD plugged in you can measure its output to the FS as an AC voltage, needs to be over 1.2VAC while cranking. Since it all has to be plugged in you would have to trim some wire insulation or poke through it to read the voltage. Or get a tool to backprobe the PMD harness. If thats there and no fuel there would be an IP issue.
 
Wasnt it a 2200 ohm resistor recommended? Does that matter? And not necessarily cutting the retun line, just jumpering the 5V to the line with the 2200 ohm resistor.
 
83GMCK2500 said:
Ok, tried all of that. Quick verification, is the CPS the sensor in the valley directly beneath the upper intake plenum where the boost sensor is located?
Click to expand...

The OPS is the one under the intake. The CPS has a long pigtail so could be in the area, normally mine is hanging out under the T-stat. The CPS is located down by the crankshaft in the timing cover on drivers side. But the 3-wire pigtail is pretty long.
 
Ok, I went and got a scanner and here are the DTC codes in the history (there were no current codes)

P0215 - Fuel shutoff solenoid (obviously since I pulled the plunger and haven't plugged it back in)
P1626 - Theft Deterrent Fuel Enable Signal Lost (most likely the culprit)
U1000 - Class 2 Communication Malfunction (probably set when I cranked the truck without the passlock module installed)

I cleared the codes, going to see if the passlock behaves this time, and if it sets any more codes.

Buddy, the resistance can be anywhere from 4700-11800 ohms, but generally it's between 2,000 and 4,000.
 
Are you supposed to cut the return line or just jumper the resistor in parallel? If you have alldata you can see the passlock return pin number on the PCM. Then check continuity between the yellow wire you cut and the PCM. If its an open circuit that would be the issue I guess, and you could run your own new line perhaps.
 
In the article I read you cut the line from the key to passlock module. The input (yellow) to the passlock module gets the resistor and it tapped into the sensor ground (orange/black wire), leaving it connected on both ends of it's circuit. The passlock module sends it's information to the PCM via the class 2 data.
 
I re-read his article, it's slightly different than the one i was reading. Luckily I made my passlock bypass something i could easily remove or change. I'm going to go change the it to 5v ref instead of the ground.
 
Yup, with the security light on all the time, you've got a passlock II failure. Good news is you can put the ESO back together and plug it in and stop chasing your tail. Bad news is you still have to chase down the fault.

There's no "U1000" code in my 98 book, but that may just be down to using an off brand scanner or the difference in a model year. there are pages for class 2 communication malfunction and the 1626 code though. I also scanned the VTD diagnostic check:

img017.jpg


img018.jpg


img019.jpg


img020.jpg


img021.jpg


img022.jpg


img023-1.jpg


img024.jpg


img025.jpg


Have a looky see at the pages, hopefully something helps you out.

You may get lucky like a break in the serial data wire as opposed to an overpriced hal sensor or module.

Also, If you were willing, you can pick up and send me a spare PCM.

I'll swap it into my truck, flash it with a passlock II disabled program (it would be my 98 L65 stock tune as I don't have a cal file for 99, that would be another 99 bucks for a VDF from Westers) and send it back to you.

No guarantees that it will work though. The 96-00 6.5 OBDII's are strange beasts. Westers has separate VDF'd for each year, some even have two VDF's for the same year. I usually order my VDF from Lyndon by VIN number. They're just that weird...

It should work, but it would be at your own risk....I've got a 99 PCM sitting ont he shelf I've been meaning to reflash with my 98 Cal file to see if it works,. MAybe I'll do it this weekend...

oh yeah, no charge for my services, you pay shipping and that's it.

Anyways, I'll just throw the offer out there.

Good luck.
 
Last edited:
Thanks BJ. I'll go through that tomorrow, and test some of those circuit for continuity, etc. One of the scenarios in there is exactly what must have happened in my truck, the PCM lost communication with the Passlock module and upon restart went into security mode, hence the non-starting. So, either a bad connection or trashed passlock module. If it was the ignition sensor, the light would blink as the passlock module would still be working, and my resistor mod to bypass it would also be working.

I sent an email to Bill Heath to see if he can just remove the security stuff from the PCM, it would honestly make things much easier.

Hopefully I can figure out whats going on after class tomorrow, i'll keep you updated.
 
You must log in or register to reply here.
Back
Top