98 GMC Suburban Revival

[DmaxMaverick]

I wondered about this.....If the pcm has a glitch and then does not like the resistor value....then the same issue all over again.

Glad you mentioned that Greg.....I thought about this after I posted on the video.

There must be a way to deactivate this system permanently ?????
Up in the great white north....probably not too much issue with a 1998 Burb getting stolen me thinks

The PCM doesn't receive the resistor value, and doesn't monitor the security status. The BCM only authenticates and sends the ignition signal to the PCM. It's simply the routine start-up exchange that relies on a long list of diagnostic successes. The P1626 and U1000 are specific to the BCM, meaning the PCM isn't complaining, other than storing the DTC's. The security protocol can be disabled through a PCM or BCM calibration mod. Writing it out of the PCM could be disastrous, as the security authentication is only one of many diagnostic checks that occur. If you happen to be adjusting the calibration for another reason, and insist you don't want the protocol, it can be written out, although I don't think it would be worth the effort/time/cost to do it for no other reason. It's easier to correct, and real hardware failures or problems are extremely rare.

[Robyn]

I can understand the need for the security device....I just hate the magic box that can leave ya stranded.....
Out in the sticks a looooooooooooong way from nowhere and the thing gets pissy....bad ju ju..

[DmaxMaverick]

You mean, like a PMD, spark control, ignition coil, ignition switch, alternator, water pump, fuel filter, PCV, oil pan plug, rubber hose/belt, pothole, idiot drivers, moose, lightening bolt, meteorite, etc. All of which are more likely to strand you, statistically.

[Robyn]

Yeah....all of those things

[Yukon6.2]

Everything we drive is a breakdown waiting to happen...
Years ago the chances of continuing home if you had a screw driver and a crescent wrench under your seat were pretty good as we all wrenched on our vehicles to keep them rolling.
So i tried the reset a couple times,10 min plus each time the security light was still on.
I will see what the chances are of getting a replacement chipped key on Monday,if no joy there i will order a replacement tumbler and key.
I did get the release for the 2/3 back seat fixed yesterday,had to take the seat apart to get the cable out.There was a lump of something had made it through the seatbelt hole and lodged at the end of the cable in the seat and infiltrated the cable and seized it.Spent an hour or so getting Honey Doo into it and now moves slick.
Had enough parts to do one rear wheel waiting for a wheel cylinder to finish up.Gravity bled the front brake circuit from the new master cylinder to the calipers.
The list is getting shorter,hopefully the running issue gets striked off with a key or replacement tumbler.
Again thanks for the help.
Thomas

[Robyn]

IIRC the 98 Burb does not use a chip key

[DmaxMaverick]

There is no chipped key. The "chip" is inside the cylinder housing. All North American GMC Suburbans, 1997-2002, are Passlock. Passlock keys have no chip. As long as the key turns the lock cylinder, the key isn't the problem.

When you run the relearn, the security lamp must go out before you start the procedure. If it doesn't, or continues to flash, it will not relearn. The 10 minute wait is only a suggestion. Most of them take only 10, some longer. There are progressive stages or modes of lock-out, and get longer with more failed attempts. 3 failed attempts starts the 10 minute lock-out, then it may increase a few minutes. In any case, as long as the security lamp is on or flashing, you cannot start the relearn.

If the security lamp starts out flashing, then stays on solid after about 10 minutes, there is a different procedure I'll have to look up. I've heard of it, but never seen it.

Begin with fully charged (healthy) batteries.
Go through your regular start routine, turn the key to ON, but clear the DTC's before turning the key to crank. Clearing the DTC's isn't supposed to be necessary, but I'd do it anyway because you can, and it's free. When you turn the key to crank, let it try to start, then stall. DO NOT turn the key to off. Leave it in the run position. Go away. Make a sandwich or something. Check on it periodically. When the security lamp goes away, DO NOT turn the key off. Turn it to crank. It should start, and continue running. Let it run for a minute, then turn it off. Wait 5 seconds, start again. Let it run a minute, then shut off. Restart to confirm. If it doesn't start after several correct relearn attempts, or the security lamp never goes out, the BCM is not reading the signal voltage. The 5V circuit is open between the BCM and switch, the lock cylinder housing has failed, or the BCM has failed.

[Yukon6.2]

Thanks again
Awesome info,I have to work away from the shop today,but as my fuel truck is warming up i will see if the security light will disappear

[Yukon6.2]

Well laid plans...
Got to my shop yesterday and priorities for the day had changed.
Opened the door and was not met with any warmth.Furnace was down.
Reznor Waste Oil furnace,usually it's an easy fix.
Not this time a high limit switch had fried,and my extra parts had not been shipped due to covid and the supply chain.They are still waiting for some parts.Told them to ship what they had i need it yesterday.Same high limit went last year,first one lasted 22 years.This one 1 year.
Found a workaround,but to risky to leave unattended.
Will try for the relearn today,plus the rest of my brake parts showed up.

[Robyn]

ALWAYS SOMETHING EH ??

Good luck with the unexpected breakdown ....

[Yukon6.2]

So after over 2 hours the security light never went out
from what Maverick wrote i will see about getting a new lock cylinder
Shop hasn't burnt down yet without the high limit,i did shut it off for the night.-17C last night.Wasn't supposed to be that cold shop was still above freezing.At least the weather has been very spring like.

[DmaxMaverick]

The security lamp behavior will determine the series of Passlock. There are 3 or 4 to date. If the Security lamp starts flashing, then changes to solid after about 10 minutes, it's a series I, which should be 1995.5 - 1998. The series II will flash for 10 minutes, then go out. Series II should be 1999 - 2001 or 2002, but these were transition years, so I'm not going to guess what they did with the Suburbans (GM has priors). TRY THIS LINK. Everything changed in 2003 with complete serial data switches and BCM ignition handling (discussed in another Duramax thread).

If you replace the "switch", you DO NOT replace the lock cylinder. You need the lock cylinder HOUSING. You will use the exact same lock cylinder and keys in the new housing. As long as the key still turns the lock, it isn't broken. The fancy part that does the electronic magic is in the housing. The key has no "chip", it is all in the lock cylinder housing.

[Yukon6.2]

Thanks again Maverick
Closest dealer is $419.00 3 to 4 weeks.
Going to have to try calling a few in other city's.
Whats the chances of a used one working if i found one?
I went to gm parts direct and the shipping was more than the part.Once converted to canadien it's about the same but their claim is a week delivery.

[Yukon6.2]

Thanks again Maverick
Closest dealer is $419.00 3 to 4 weeks.
Going to have to try calling a few in other city's.
Whats the chances of a used one working if i found one?
I went to gm parts direct and the shipping was more than the part.Once converted to canadien it's about the same but their claim is a week delivery.

[DmaxMaverick]

I'd go for used, if you find one. Chances are good that it will work. Due to your cost of getting new, I don't think I'd pay that for what may not be the problem. For that kind of money, I'd try the resistor bypass and forget all the security junk.

According to the parts crossover, there are several GM models that used the same switch from 1997 to 2002. GM part # 26075995 . The Suburban, pickups, Yukon, and Tahoe are specific, only 1998 and 1999. Express/Savana vans are 1997 - 2002. S-10/Astro/Safari/Blazer/Jimmy/Bravada, and Isuzu Hombre are 1997.

I don't know how this translates into Canadian, but it's a starting point if you need it:

https://www.amazon.com/Genuine-GM-26.../dp/B00GU9Z4GA

[Robyn]

For that sort of coin....I would watch the video and install the appropriate rated resistor...

$400 + is way too steep....Better to spend the $$$ on other parts that need it.....
I really doubt that theft is that big up there in the great north to worry about a 20 plus year old rig getting ripped off.

If you decide to do the resistor route....EBAY...Once you know what ohm value the system is asking for.....
You can get a few of these little devils for a few $$$

https://www.ebay.com/itm/16362517017...wAAOSwmQxfh62h

Come right to your mail box.

I would do the procedure described to get the ohm reading.....then disconnect the batteries over night.

Reconnect and retest.

If the system asks for the same ohm value the second time....order that value...
Install as per the video and install.

Tape things up so nothing can short...

Should work.

This will use a less than $5 investment to get around paying $400
If this does not solve the issue....no big $$$ loss on the problem....

Check out the ebay listing
Scroll through the values in the drop down...choose what you need....Done deal

[DmaxMaverick]

The resistor value is simple, as long as it returns voltage within the operable range. You can either read the switch value of a similar vehicle and try to match it, or simply use a 1.8K to 2K ohm, and do a relearn. A relearn likely has to be done, in any case, even if you match the stored value. The range is somewhat generous, but out of range is out of range, and it gets rejected. If it works without a relearn, give luck the credit.

Still, the Security Lamp behavior is a bit vague. The BCM times the event, and behaves differently at specific times. The Lamp has 3 modes: On; Off; Flash. If nothing you do ever changes the mode (other than turning the key on and off), it's a good possibility the BCM is corrupt or damaged. It's important to watch the timing, and note what changes. Depending on the model, and model year, the behaviors can be different. Don't give up, just yet, with verifying the current components are actually failed. Most often, your timing and the vehicle's timing doesn't line up, and a failure is assumed when it shouldn't. The result is throwing expensive parts at something that isn't broken. Any time battery power is taken away, or the batteries are significantly discharged or failed (to a point it won't crank well), it can mess with the computers, and they will often dump or corrupt their writable values (such as the Passlock). Usually, a couple successful start cycles will correct this, but it doesn't happen if it won't start and continue to run.

Unfortunately, the process(es) take time, and there's no way to speed it up. If you don't have the time and patience to go through it, you won't fix it. Don't discount dumb luck though, if it suddenly works after a bunch of messing with it. If it inexplicably starts to work normally, you still have an original problem that may (very likely) revisit at the absolute worse time.

1. What mode at key ACC only (not ON, no start attempt)?
2. What mode at key ON (no start attempt)?
3. What mode immediately after start attempt?
4. What mode 10 minutes after each of the above, separately?

Also note, a 10 second period is necessary between any key position change. For example, if a key Off, then key ON is needed, key Off and wait 10 seconds before key On.

[Yukon6.2]

Thanks a bunch everyone
I went through my back yard and found one truck that had the passlock tumbler housing,unfortunately the key is MIA from the truck.I did get the housing removed and will see about removing the tumbler today.
Living in the sticks have a distinct disadvantage if you need something now.Like resistors,to get any from eBay is a couple weeks if they ship to Canada.
I did find a new part a lot closer and $100 cheaper,at this time i have to toss the money at it in case i need it.Time is starting to slip away and would like to get some driving time on the truck before i head away from home.
If my luck runs like normal...
Whats the options to deal with the BCM? Re flash by a vendor?
Hopefully the demons get exersiced it's a pretty nice Burb and deserves to be making miles on the open road.The main reason i picked it to revive was the clean body,engine compartment,and interior.No aftermarket goodies have been butchered into it.

[DmaxMaverick]

If you have a compatible lock cylinder housing and no key to remove the lock cylinder, you can bore the cylinder keyway to release the pins. Don't force the cylinder to turn, it will destroy the housing. The pins are very hard, but the cylinder is soft (aluminum or pot metal, usually), so choose a bit slightly larger than the tallest cut in the key. Be careful to not damage anything outside the cylinder, and bore to only the depth of the key. What model and year is the lock cylinder from? If it isn't from a vehicle I listed above, it won't likely work. If they don't physically fit, they are also wrong, internally.

BCM repair depends on the cause of failure. They can often be recalibrated, but it requires someone (dealer, tech, etc.) with the equipment and a calibration image matched to your VIN. Other than that, it will require the purchase of another BCM, and the calibration done by the same. Another TDP member just went through a replacement with a vendor that sent one, pre-programmed to the VIN. I'll get that info to you, if needed.

You don't have to order resistors. Any electronics store should have a selection of them. You can also cannibalize them from other devices. Any expired electronic device (TV, radio, VCR) will have an assortment on the PCB, and likely several that will work. If you can't read the coding on them, a little time with a VOM will gitter done.

[Robyn]

I figured that having a Radio Shack or similar shop close by was likely not in the cards ..

A few days in the mail is no biggy ...and you can get the exact value needed.