Security light stays on...sometimes...

[DennisG01]

OK, the new engine was put in a little over a week ago. Now, sometimes the security light will come on while driving. Sometimes it goes off by itself, sometimes if won't go off till I turn the engine off and restart. I had codes pulled both at Autozone and then a local injection shop with a Tech2 (or at least I think it's a T2 since they are the ones that do my IP timing). No codes were present.

I do not notice any drivability issues. With one exception: Over the course of the first two days with the new engine, 2 or 3 times the truck would not start when the light was lit. After sitting for about 10 - 15 minutes it would then start. Now, this is reminiscent of a problem I had a few years ago and it turned out to be the ignition module (apparently there is a 10 - 15 minute "reset" period). But since those first couple of days, there hasn't been any starting issues.

Should the security light leave a code?

Any ideas?

[Robyn]

This security light ????????//

Is this a factory item in the dash or an aftermarket installed unit.

Your unit is a 98 ao may have something I have not seen as yet.

If it does have a security interlock system, this certainly could cause issues including a no start.

Best to have a look at the schematic and see what the deal is.

Robyn

[DennisG01]

Yes, it is stock. Top right hand corner of the dash is a little yellow light that says "SECURITY".

[diesel65]

It is called the Passlock system, if someone was to yank the ignition lock cylinder and try to start the truck with a screwdriver, the Passlock module will not receive a signal that it is looking for and then in turn tell the PCM not to allow the engine to run.
The symptom when the Passlock is working is that the engine will fire when first cranked and then just keep cranking when you are trying to start the truck.
This system function is the same on the gassers.
There are codes available to diagnose but you have to go in body codes.
The Passlock module is integrated with the EVO system (variable power assist for steering), the module is located under the radio behind the dash.

Dennis problem is most likely that the ignition switch needs to be replaced, I have done a few ignition switches.
When you are able to start the truck and the security light is on, the module received
a signal but may not be a valid signal.

Passlock was installed in 1998.

[DennisG01]

It is called the Passlock system, if someone was to yank the ignition lock cylinder and try to start the truck with a screwdriver, the Passlock module will not receive a signal that it is looking for and then in turn tell the PCM not to allow the engine to run.
The symptom when the Passlock is working is that the engine will fire when first cranked and then just keep cranking when you are trying to start the truck.
This system function is the same on the gassers.
There are codes available to diagnose but you have to go in body codes.
The Passlock module is integrated with the EVO system (variable power assist for steering), the module is located under the radio behind the dash.

Dennis problem is most likely that the ignition switch needs to be replaced, I have done a few ignition switches.
When you are able to start the truck and the security light is on, the module received
a signal but may not be a valid signal.

Passlock was installed in 1998.

Hmmmm. 3 years ago (13,000 miles) when I had this problem, the dealer diagnosed the "ignition cylinder" as being bad with code B2960 (which I assume stands for "body" as you mentioned). Could "cylinder" and "switch" be the same thing? The dealer replaced:

Ignition Cylinder - part# 26049532 list price of $37
Case Assembly - part# 26049449 list price of $148

They also did a Passlock relearn. I wondering if since my truck has been sitting without and engine and batteries for nearly a year, could I maybe just need another "passlock relearn"?

[DA BIG ONE]

Hmmmm. 3 years ago (13,000 miles) when I had this problem, the dealer diagnosed the "ignition cylinder" as being bad with code B2960 (which I assume stands for "body" as you mentioned). Could "cylinder" and "switch" be the same thing? The dealer replaced:

Ignition Cylinder - part# 26049532 list price of $37
Case Assembly - part# 26049449 list price of $148

They also did a Passlock relearn. I wondering if since my truck has been sitting without and engine and batteries for nearly a year, could I maybe just need another "passlock relearn"?

I've had the switch go bad too, was claimed that heavy key ring can damage switch. Now just have key fob and a couple of keys only.

More likely than not you need to do passlock relearn, I remember when I had installed a BH ecm a passlock relearn was required but I have forgotten how to do it. Surely, some on this forum can describe the process...........You try it and go from there!

Good luck there!

[DennisG01]

Just an update:

About 4 weeks ago I went to the dealer with the hopes of a re-learn taking care of the problem. He diagnosed the switch being bad (again) and said since the light is intermittent, a re-learn won't do anything. Oh well.

But, I still wasn't convinced that the switch was entirely bad so the next day I went to a local radio/stereo installer (they've been around for over 60 years in this area) and told them the deal. He looked at how the remote starter was installed (which was by someone else) and said that's probably the culprit. He did some re-wiring (and took out the remote start function, for now). So far, the security light hasn't been back on (knocking on wood as I type;)). If it continues to stay out, they said they can hook-up the remote start function again -- the right way!

Should of gone to them first!

[N9Phil]

I have the same problem with a 99 Gas Suburban that I just picked up a few weeks ago (I looked for another Diesel Suburban but couldn't find one) If the security light comes on, I can shut off the engine and turn the key over and the problem goes away. There is a 10 minute reset when the lock out occurs. Since mine has not caused any problem running, I haven't completly checked it out yet. I have the shop manual for the 99 and I can probably get you the info that you need to do the reset.


Phil

[DennisG01]

Thank you, Phil. I believe the problem is fixed, but who knows. When you have some time, I'll take you up on your offer - but it's no rush. Thank you! I'm sure others can benefit from knowing the procedure, as well.

[DennisG01]

Everything has been fine, until a few weeks ago. I'm posting back here, instead of starting a new thread, because the current problem might be related.

About 3 or 4 weeks ago, the truck wouldn't start (turned over fine, but wouldn't fire). I then moved the gear selector through the gears and back to park... then it started just fine. I wrote it off as "just one of those things".

Now, this morning, there was a bit more of a problem. Lift pump ran, but the engine wouldn't start. As before, it turns over like a champ, just won't fire. I wiggled wires in and around the IP a few times (just for fun, I guess), but still no luck. I came back about 15 minutes later and it had magically fixed itself. Drove it to work and it drove great.

I do not have a security light showing. I have not re-installed the remote start.

I'm going to stop by an Autozone to check for codes after work (hopefully they can get into the "body" codes) and I'll report back. In the meantime, any ideas?

[Artworks]

Check the ground wire at back of engine by the glow relay. Mine was bad, only couple stands of wire holding, and I was having some no starts once in a while, glow / wait to start light wouldn't come on and after I fixed it my air bag light went off after about 6 months of staing on !!!

[DennisG01]

Thanks, Art. In my case, I'm not holding my breath on that being the problem, but it's easy enough to check (my WTS light is operational -- I also replaced all my grounds with SS, braided straps). Thank you for the suggestion - much appreciated! I'll take a look later today.

[DennisG01]

Ha! Egg on my face! My GP controller is not mounted to the firewall - it's mounted direct to the rear, port corner of the engine via a metal bracket -- no ground wire.

Stopped by Autozone - their code reader can't pull a body code.

It started up just fine after work. I can see already this is going to be a pain in the neck... trying to track down the culprit, I mean. Since it's probably going to be sporadic.