Fuel system help.... maybe

exp500 · Jan 4, 2022

Charles, Thanks for the update! Because of the "clutter" and no ability to easily and correctly search these forums it may be better to stay on this thead. Only start a new one if you resolve problem and create a sticky or Troubleshooting help post.

From what I have seen on VATS, the dash light flashing on momentarily and going out is the correct operation if theft is not active. Light would stay on if active. A Tech2 or similar hi end scanner would verify a theft shutdown or correct operation with the corresponding codes. Where do you live? several members here have Tech2's willing to help.

There is little info available for the internal workings of this system and UTube wont likely post "How to steal a Chevy".
There are 10+ posts here unsolved on no start similar to you.
I recommend you do some more diagnostics to "prove" this is your issue. Unplug the big connector on top of intake for F/I harness and verify pin connections were good/deep. Also noid light tests here- you can use a 194 bulb for a noid lite. The VATS injector shutdown shuts off the ground inside computer. So a bad engine/computer ground could be your cause, with some grounds under dash.
The factory manual is a big help here. Go here- you have to join to download-GMT400 CK Manual Project - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Keep us updated! We are here to help.

crammit442 · Jan 4, 2022

exp500 said:
Charles, Thanks for the update! Because of the "clutter" and no ability to easily and correctly search these forums it may be better to stay on this thead. Only start a new one if you resolve problem and create a sticky or Troubleshooting help post.

From what I have seen on VATS, the dash light flashing on momentarily and going out is the correct operation if theft is not active. Light would stay on if active. A Tech2 or similar hi end scanner would verify a theft shutdown or correct operation with the corresponding codes. Where do you live? several members here have Tech2's willing to help.

There is little info available for the internal workings of this system and UTube wont likely post "How to steal a Chevy".
There are 10+ posts here unsolved on no start similar to you.
I recommend you do some more diagnostics to "prove" this is your issue. Unplug the big connector on top of intake for F/I harness and verify pin connections were good/deep. Also noid light tests here- you can use a 194 bulb for a noid lite. The VATS injector shutdown shuts off the ground inside computer. So a bad engine/computer ground could be your cause, with some grounds under dash.
The factory manual is a big help here. Go here- you have to join to download-GMT400 CK Manual Project - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Keep us updated! We are here to help.

I'll only start a new thread if the issue is definitely resolved. One way or another, we're going to get to the bottom of this. From everything I've seen, I think you're right that the anti theft dash light flashing briefly and then going off is normal. When the key is first turned on the pump cycles. When it's turned off you can hear a bunch of short "clicks" right at the big connector on the intake. I actually did pull the connection and all pins and sockets were clean and dry. My Dad's going to run by my house in a little while and scan the codes. It's just an inexpensive Bluetooth scanner, but it may pick up something. I'll join download the factory service manual and check grounds also. I left a message with the company that rebuilds the Passlock modules. Hopefully they can give me some more specific tests to try. I'll keep updating this thread and please suggest anything else you think of. Thanks.
Charles

crammit442 · Jan 4, 2022

Another hare brained thought. Im not sure how the entire Passlock system works, but the keyless entry is pretty sketchy with my truck. It's usually easier to just unlock the door with the key. Any chance security could "engage" because the system thinks the door was opened without disarming? The system doesn't chirp or flash the lights when when keyless entry is used. My system does not use a key with a pellet/chip.
Charles

crammit442 · Jan 4, 2022

Small update. My Dad ran by and scanned the truck and there are no codes. The battery has been disconnected multiple times while doing the fuel pump so it may not throw any codes until it runs more than 3-4 seconds. A buddy of mine owns a car stereo shop and has had to use a key bypass many times to install remote start systems. I talked to him about it and his best guess is that the column/switch isn't detecting that the key has been turned. I'd still think it would show an anti theft light, but it's easy to bypass and reverse if that isn't the problem. Still haven't heard anything from the guy that sells rebuilt Passlock modules.
Charles

exp500 · Jan 4, 2022

Charles- You may be onto the solution! Especially because Not having a chip key on a 99 and the way your remote acts..... Call your friend again and pick his brain about bypass install.... You may have one... resistor failing/ bad ground/ exc...
You could pull your column covers and see if fingers been in there.Also possible is broken wires from tilt. Good luck.

crammit442 · Jan 4, 2022

exp500 said:
Charles- You may be onto the solution! Especially because Not having a chip key on a 99 and the way your remote acts..... Call your friend again and pick his brain about bypass install.... You may have one... resistor failing/ bad ground/ exc...
You could pull your column covers and see if fingers been in there.Also possible is broken wires from tilt. Good luck.

I actually pulled everything to get to the module last night as well as the column covers. One of the YouTube Passlock videos I watched suggested grounding the purple wire to the module. It claims to fix it whether the module works or not. Everything was spotless so I don't think anyone's ever been in there. The truck only has about 114k miles. You don't have to cut the wire to expose the conductor so I didn't have much to lose. A bunch of comments on the video said it worked, but it didn't on mine. There are a bunch of videos showing bypassing just the ignition switch part of the system, but it doesn't fix a bad module. It's also easy so I'm going to try that tonight. Here's a link to the "no resistor bypass" video.

Charles

east302 · Jan 4, 2022

exp500 said:
A Tech2 or similar hi end scanner would verify a theft shutdown or correct operation with the corresponding codes. Where do you live? several members here have Tech2's willing to help.

Going by memory here, but I think the Passlock codes are B#### and may require a higher-end scanner to access. I use a knock-off tech2 on mine and know you can get them from it; I don’t think that they were in the same menu hierarchy as the regular P codes. If the Passlock is killing the injectors, it should store a code.

Technically, you’re supposed to clear the codes before trying the relearn, but here’s the procedure in case you don’t have it.

A quick fuel pressure check wouldn’t hurt (spec is 60-66 psi key on engine off) and it should hold within, say, five pounds for a few minutes after turning it off.

iamdub · Jan 5, 2022

crammit442 said:
...Based on the VATS pdf, it looks like my truck is uses Passlock. I followed the VATS relearning procedure several times with no change.

I always thought PassLock was just the name of that particular version of GM's VATS. "VATS" is just the universal, all-encompassing term used for all of GM's anti-theft systems (PASSKey-1, PASSKey-2, PassLock I, PassLock II, etc.).

If you've ever considered getting this thing tuned, you could have VATS disabled as part of that. You might wanna look into that versus the cost of a replacement module. Get more bang for your buck.

Disabling VATS in the tune would allow the engine to run (assuming this is your problem). But, a fault with VATS might keep the "SECURITY" light illuminated on the cluster. You could just remove the light (LED?) or cut one of the legs if it's soldered to a PCB.

crammit442 · Jan 5, 2022

east302 said:
Going by memory here, but I think the Passlock codes are B#### and may require a higher-end scanner to access. I use a knock-off tech2 on mine and know you can get them from it; I don’t think that they were in the same menu hierarchy as the regular P codes. If the Passlock is killing the injectors, it should store a code.

Technically, you’re supposed to clear the codes before trying the relearn, but here’s the procedure in case you don’t have it.

A quick fuel pressure check wouldn’t hurt (spec is 60-66 psi key on engine off) and it should hold within, say, five pounds for a few minutes after turning it off.

View attachment 359683

I appreciate the information. I've read the relearn process, but not in that much detail. I've tried it several times with no success. I replaced the fuel pump Saturday so I think I have good fuel pressure, but I'll have a gauge Sunday. I'm starting to understand why none of these threads are ever fully resolved. This is like some crazy snipe hunt. Every time I think I'm on to something the plot twists and the hole gets deeper. I heard back from the guy that rebuilds Passlock modules and he said if it was bad the security light should stay on and mine doesn't. I found a new ignition cylinder that can be keyed to my existing keys, but after talking to them, apparently the cylinder only contains the magnet and the hall effect sensor is in the ignition lock housing. At this point I think I'm going to take a step back and figure out how to test everything else possible before just buying stuff. It's looking like it's actually pretty hard to fully eliminate or bypass the whole Passlock system. I laughed when I read about people actually scrapping otherwise healthy trucks because of this, but I'm starting to get it

.
Charles

crammit442 · Jan 5, 2022

iamdub said:
I always thought PassLock was just the name of that particular version of GM's VATS. "VATS" is just the universal, all-encompassing term used for all of GM's anti-theft systems (PASSKey-1, PASSKey-2, PassLock I, PassLock II, etc.).

If you've ever considered getting this thing tuned, you could have VATS disabled as part of that. You might wanna look into that versus the cost of a replacement module. Get more bang for your buck.

Disabling VATS in the tune would allow the engine to run (assuming this is your problem). But, a fault with VATS might keep the "SECURITY" light illuminated on the cluster. You could just remove the light (LED?) or cut one of the legs if it's soldered to a PCB.

This is all still pretty confusing to me. I'd never even heard of VATS before your post Monday. I think you're right that all the versions of VATS are sort of under the same umbrella. Even though my system (Passlock) doesn't use a chip or resistor key like PK/2,3, if I'm understanding it correctly, the system shuts off the fuel injectors until the ignition switch tells the system it's been turned has been turned by a real key. I saw that the system could be turned off in a tune. I don't actually need it tuned for what I do, but who are some recommended tuners and what does it typically cost? I guess before I look into that option I want to be sure my ignition switch is sending good key information to the rest of the system. Thankfully I don't have to drive it right now so I can afford to take a step back and do more testing before waste more money on things that may not be the problem. I really appreciate all the suggestions and feedback.
Charles

Fuel system help.... maybe

exp500

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