Security Light Issue - SOLVED

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SBellew

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Good morning. My 99 OBS Tahoe is driving me crazy. I have a solid Security light and she will start and run for 2 seconds. I have attempted the Passlock relearn, but the light does not go out after the 10 minutes. I have replaced the key cylinder and cylinder lock housing. I also got another module with the same GM part # from a salvage yard. The light refuses to turn off after the 10 minute period during the relearn procedure. I searched and could not find any info for when this happens and would appreciate any suggestions. Thanks in advance.
 

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Good morning. My 99 OBS Tahoe is driving me crazy. I have a solid Security light and she will start and run for 2 seconds. I have attempted the Passlock relearn, but the light does not go out after the 10 minutes. I have replaced the key cylinder and cylinder lock housing. I also got another module with the same GM part # from a salvage yard. The light refuses to turn off after the 10 minute period during the relearn procedure. I searched and could not find any info for when this happens and would appreciate any suggestions. Thanks in advance.
what about the key?
 
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SBellew

SBellew

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The keys for the switch were included in the new set.
 

east302

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Do you have a good scanner like a Tech2 or Snap-on? It’s almost certainly stored a few codes (B and sometimes a U prefix) and the GM manual has the diagnostic procedures for each.

You can download PDFs of most years at this site:


I don’t remember if they have 99 - go with 98 if that’s the case and it’s probably close enough if not the same. Volume 1, Section 9D has the Passlock info. A subscription to alldatadiy.com is another option and is exactly the same material as the GM manual.

One thing that the manual does mention repeatedly is to clear any Passlock codes before doing a relearn. It’s probably not nuclear-level-biohazard critical since many have successfully reprogrammed without clearing codes, but you may just be the unlucky exception.

If you don’t have a scanner, take a look at the code tables anyway. It’ll probably give you some ideas of things to check.
 
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SBellew

SBellew

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It shows a P1626 DTC (Theft Deterrent Fuel Enable Signal Not Received).
1684366687920.png
I tried clearing it and doing the relearn and the Security light still did not go out after 10 minutes. It also shows that passlock is not equipped on a system scan.

1685074441140.png

Running a live scan during cranking, the VTD fuel disable goes to active, then back to inactive.
1685074841735.png
 
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exp500

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Sometimes, parts replacement is a problem. I think STRATTEC was OEM key. Fords in this time frame were a problem area.
Does your scanner have a program key function?
 
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SBellew

SBellew

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Sometimes, parts replacement is a problem. I think STRATTEC was OEM key. Fords in this time frame were a problem area.
Does your scanner have a program key function?
From talking with a locksmith, the key in passlock 2 is not anything special in the system, only the lock cylinder, housing and passlock module. Same issue existed before anything was changed out. VATS and passlock 3 have special coded keys. My scanner sees no passlock module, not sure if that's a scanner or module issue. It's said not installed on both modules.

My scanner: https://www.amazon.com/dp/B09XV8VR35
 

east302

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Here is the P1626 diagnostic from volume 3 of the manual. If it isn’t communicating with the Passlock module, then it’ll refer back to the Module diagnostics section which is Volume 1 (9D) of that link that I posted earlier. It’s too many pages to copy onto here, but it would be worth looking at.

One thing it does mention - see if fuse 4 (gauges) or 21 (sec/strg) is blown.

I guess it depends on if your scanner has the functions needed to get to the information mentioned in GM’s diagnostics. These things can be annoying, for sure.

You are correct about the key - there’s no chip in it and the Passlock stuff is contained within the steering column.

IMG_5480.jpeg
IMG_5481.jpeg
IMG_5482.jpeg
IMG_5483.jpeg
 
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SBellew

SBellew

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Thank you. I downloaded the 4 volumes last night and am getting ready to start tracing wires. Long 3 day weekend will be perfect. Gotta build my dad's 4.2L in his F150 this weekend too.
 

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