Fuel system help.... maybe

[crammit442]

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 appreciate the link. I've been looking at the different manuals and I'm a little confused about which one applies to the . On another note, I found a module (New Rockies) that claims to permanently fix all VATS issues. It uses a universal module with adjustable dip switches and different installation instructions for specific vehicles. The website looks a little like an "as seen on TV ad", but I was able to find several installation videos on YouTube with lots of positive comments. They claim to have a 30 return policy with a lifetime replacement warranty. It's $300, but could be money well spent if it permanently fixes it.

Charles

NEWROCKIES Inc. Passlock Bypass disables the ENTIRE system.

The only Passlock Bypass Module that disables the ENTIRE system FOREVER. It works for VATS, PassKey and Passlock. 30 days money back guarantee.

newrockies.com

 

[iamdub]

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

Tuning prices vary, particularly by what all is done. It's usually around $150 at a minimum. Using HP Tuners as an example, most vehicles of this type require two credits to tune at $50 each, so $100 in credits. If a tuner is just making basic changes and not really tuning for power, etc., they might tack on something like $50 for their labor, totaling $150. I had mine tuned to disable AFM, delete the rear O2 sensors (for future plans of catless headers), remove the speed limiter and maybe some other small things for $150. For an actual power tune where they use their knowledge and experience to read and modify the fuel, timing and shifting tables, it would be a few hundred more, as it very well should be. It's not for the inexperienced.

For your purposes, I'd just find a local reputable tuner, explain what you're doing and go from there. It shouldn't cost much. They might even suggest a few small extras or tweaks they'd include as freebies since most of all they're doing is checking or unchecking boxes.

 

[crammit442]

Tuning prices vary, particularly by what all is done. It's usually around $150 at a minimum. Using HP Tuners as an example, most vehicles of this type require two credits to tune at $50 each, so $100 in credits. If a tuner is just making basic changes and not really tuning for power, etc., they might tack on something like $50 for their labor, totaling $150. I had mine tuned to disable AFM, delete the rear O2 sensors (for future plans of catless headers), remove the speed limiter and maybe some other small things for $150. For an actual power tune where they use their knowledge and experience to read and modify the fuel, timing and shifting tables, it would be a few hundred more, as it very well should be. It's not for the inexperienced.

For your purposes, I'd just find a local reputable tuner, explain what you're doing and go from there. It shouldn't cost much. They might even suggest a few small extras or tweaks they'd include as freebies since most of all they're doing is checking or unchecking boxes.

After more research I've decided to go this route. I saw a shop recommended on another forum and talked with them this morning. He thinks the VATS disable should work. It's $150 and I should have the PCM back by the end of next week. I'll link the thread where I read about this below. It's a later vehicle, but it's still the best thing I've found about how VATS/Passlock/Passkey works. I appreciate all the help and I'll keep this updated.
Charles

PassLock Ignition Switch Disassembly & Modifying

www.355nation.net

 

[exp500]

Charles- Ref posts15, 20- You should have a chip key for your year!
I would at least pull the codes with a tech2 or similar before investing in proposed mod. That would pay for your very own vcx nano with beer money left over!

 

[crammit442]

Charles- Ref posts15, 20- You should have a chip key for your year!
I would at least pull the codes with a tech2 or similar before investing in proposed mod. That would pay for your very own vcx nano with beer money left over!

I thought the same thing too until I looked at the VATS relearn guide below and compared my key. When I talked to my buddy that owns the car audio shop he said the same thing because they have to bypass the key/switch to install remote start systems. I've actually solved (at least temporarily) the problem. It's a long story and I'll put it in a separate post after this. Thanks again for the help.
Charles

GM Security Relearn Procedure - Module Experts

moduleexperts.com

 

[crammit442]

Well, the Tahoe is alive again. Time for the walk of shame. I've managed to squeeze 6 days of pain and misery out of a 45 minute/5 cent repair. I may make try to make a new thread for future reference if what I've learned can help anyone else avoid the same thing. An accurate fuel pressure test might have sent me in a different direction, but I'm not sure. The truck has been hard starting for a couple of years, but was always fine after the first start of the day. A couple of weeks ago it would still start, but I couldn't get it to run more than about 3-4 seconds. I still had compression and spark so I assumed the fuel pump had finally quit. Last Saturday I dropped the tank and replaced the pump and figured everything would be good. I couldn't believe it would still only run for a few seconds. I spent Saturday night and Sunday searching this forum, YouTube, and everywhere else before starting this thread. I'd never even heard of VATS until iamdub said my issue sounded like an anti theft problem. If he hadn't mentioned it I probably wouldn't have ever figured it out. Even though the symptoms were right I didn't have a flashing or steady security warning light. When searching for VATS problems I saw how many other people had similar unresolved problems. Passkey, II, III/Passlock all turn off the fuel injectors if a "good key" signal isn't sent from the ignition switch to the BCM. Some of the keys are plain, some have resistors, and some have a transponder. Totally confusing. Every potential solution seems to just add more variables and don't end up working for most people. There are a bunch of videos on bypassing the Passlock version using a resistor, but I couldn't get a consistent resistance valve from my switch so I didn't try it. I found a place that rebuilds Theft Deterrent Modules (TDM), but he said it probably wouldn't fix my problem because the warning light wasn't on. Tuners can disable VATS, but I haven't been able to get firm answer on whether it'll fix a system that has already quit. After reading everyone's suggestions I decided to try the resistor bypass before spending any more money. I called my buddy at the car audio shop this afternoon and he left me a bag of assorted resistors that could be wired in series to get any value needed. I still got wonky readings from my switch, but decided to start with a 3k ohm resistor. After temporarily installing it I turned on the ignition switch and the flashing security light finally came on. I followed the Passlock relearning process and it worked exactly like it was supposed to. During the 10 minute relearn sessions, the flashing light worked down to the second on my timer. This was a big circular process, but it would have been a lot worse without everyone's suggestions and feedback here. Putting everything in writing and rereading everything really helped. Hopefully the fix will stick long term. If it doesn't I think I'll be way ahead going forward. I'll keep this updated either way. Sorry for the long story, but it's been a LONG week. Thanks again!

Charles

 

[crammit442]

Double post.

 

[exp500]

No walk of shame due! Congratulations on the repair !
I had a ford with this system beat me up pretty bad till I modified the relearn cycle thru the scanner to learn new keys, 3-4 hrs to fix after diagnostics. I was the 3rd to try and fix, ford dealer had it 2 weeks. Failed at the last step repeatedly. It's still on the road.
I'm still curious about your repair resistor placement as I'm running 12 work trucks and 20+ years is a long time for electronics to last. Private Message (PM) me. so its not public.

 

[willxfs]

Glad you got this sorted out and thanks for keeping us updated!

 

[crammit442]

No walk of shame due! Congratulations on the repair !
I had a ford with this system beat me up pretty bad till I modified the relearn cycle thru the scanner to learn new keys, 3-4 hrs to fix after diagnostics. I was the 3rd to try and fix, ford dealer had it 2 weeks. Failed at the last step repeatedly. It's still on the road.
I'm still curious about your repair resistor placement as I'm running 12 work trucks and 20+ years is a long time for electronics to last. Private Message (PM) me. so its not public.

Please send me a PM. I can't seem to send one to you.