Notices
C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1989, No crank, VATS/PASSKEY problem and workaround

 
Old 07-09-2019, 04:16 PM
  #1  
Scott Garner
Junior Member
Thread Starter
 
Member Since: Apr 2019
Posts: 4
Likes: 0
Received 2 Likes on 2 Posts
Default 1989, No crank, VATS/PASSKEY problem and workaround

Subtitle: How to completely bypass VATS and PASSKEY for $20.

I've already implemented the workaround, and I'm posting this as a reference for the internet, because I searched and could not find my very specific problem set, with a proper explanation and the workaround fully documented. My hat's off to the guy at https://vatssucks.wordpress.com/, but with all due respect, he stops short of the real bypass and only recommends an ECM reprogram. There is a much cheaper, quicker, and easier way...

1989 Convertible L98 w/electronic door locks

Symptoms
  • Turn ign key, dash lights up fine, no crank
  • Non-ignition key anti-theft features work normally (arming, disarming via door locks)
  • Security indicator lamp does all the normal things when ign key is not present
  • Security indicator lamp goes out immediately when ign key turned turned to On
  • Security indicator lamp blinks when ign key turned to Start (and of course, there is no cranking at the engine)
Note: there has already been installed and working for a while, the "VATS bypass" resistor between the ign lock cylinder and PASSKEY module. This little workaround is commonly called "VATS bypass" and, as I've learned, it's really only a partial VATS bypass. There's more to VATS than just the resistor pellet in the ign key.

Troubleshooting
According to the FSM, when the ign key is turned to ON, the security indicator lamp should go solid for two seconds before going out. This was not happening. It would do its normal blinking/solid/off routine for the arming/disarming of the anti-tamper alarm that is governed by door locks and hood/hatch releases, etc. But as soon as the ign key was turned to ON, the light went out. When turned to Start, instead of the engine cranking, the security light blinks. This was the behavior that I searched for, and while I found one or two other reports of this, I didn't see any resolutions. I'm not saying no one answered the question, just that I couldn't find it, and hence, this write-up. The FSM instructs to do the "Security Indicator Voltage Test" (8A-133-14), which is testing for battery voltage in the dark green (#4) wire, and if it's present (it was), then it stops here and says replace the PASSKEY module.

I took the PASSKEY module out of it's little plastic house and really looked for any visual signs of problems, and there were none. I'm used to seeing problems with PCBs and have found and fixed a lot of them, e.g. cold solder joints in the electronic dash and climate control modules, burned resistors, leaky caps, etc. The two major online parts suppliers that I use both sell this thing for about $350, but neither have it in stock.

Note: jumping the VATS starter relay does allow the engine to crank with the key, but it won't start (because the fuel injectors are not operating, because the ECU is not seeing OK signal from PASSKEY).

Workaround
I don't call it a "fix" because it doesn't fix anything. But it will completely bypass and disable VATS, at least as it relates to ign key stuff.
  • Go on Amazon and search for "VATS PASSKEY module." ~$20 shipped. This little guy will deliver that particular 5v 30hz signal that the ECU needs before it allows the fuel injectors to pulse during the start process.
    • Your PASSKEY module is behind the "breadbox". Find it and unplug it.
    • From the PASSKEY connector, jump red to bypass red, black to bypass black and bypass blue, dark blue to bypass white
      • bypass red needs ign voltage
      • bypass black is ground
      • bypass white is the special signal the ECU needs
      • bypass blue and green: these determine the mode. To get the signal you need, ground the blue wire and clip or tape-off the green.
  • Unplug the starter relay behind the multi-use panel in the dash. From the connector, jump the outer yellow and green wires (#1 and #5).
  • I'm not sure if the resistor at the ign cylinder needs to be installed at this point, but I already had it in there, so I left it. I don't think it needs to be there, though.
  • I haven't done this yet, but it's probably not a terrible idea to have a "kill switch" that would allow you to manually enable VATS. Maybe put on the red wire?

GM VATS PASSKEY Bypass, ~$20 on Amazon



Behind the breadbox, PASSKEY and starter relay bypassed
Scott Garner is offline  
The following users liked this post:
RalfKramden (07-11-2019)
Old 07-11-2019, 09:02 AM
  #2  
RalfKramden
CF Member
 
Member Since: Feb 2018
Location: NY
Posts: 60
Received 11 Likes on 10 Posts
Default

A question. I bought this awhile ago but haven't installed it yet due to other projects in the way for now. You unplug and leave unplugged the connector for the

PASSKEY module? Then you connect the wiring as per the instructions? Just want to pin it down. I also have the resistor that will match my key so I'll install

that as well (belt & suspenders kind of guy).
RalfKramden is offline  
Old 07-11-2019, 11:41 AM
  #3  
Scott Garner
Junior Member
Thread Starter
 
Member Since: Apr 2019
Posts: 4
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by RalfKramden View Post
A question. I bought this awhile ago but haven't installed it yet due to other projects in the way for now. You unplug and leave unplugged the connector for the

PASSKEY module? Then you connect the wiring as per the instructions? Just want to pin it down. I also have the resistor that will match my key so I'll install

that as well (belt & suspenders kind of guy).
Thatís right. Leave PASSKEY module unplugged after you install the bypass. If you think of it, do this part first, then disconnect the wires that read the resistor off the key, and see if it all works.. Iím curious about that.
Scott Garner is offline  
The following users liked this post:
RalfKramden (07-11-2019)
Old 07-11-2019, 12:02 PM
  #4  
RalfKramden
CF Member
 
Member Since: Feb 2018
Location: NY
Posts: 60
Received 11 Likes on 10 Posts
Default

Originally Posted by Scott Garner View Post
Thatís right. Leave PASSKEY module unplugged after you install the bypass. If you think of it, do this part first, then disconnect the wires that read the resistor off the key, and see if it all works.. Iím curious about that.
Ok, Thanks and I'll try that first. I *think* that the resistor bypass will be unnecessary but we'll see. Probably get on it in about 2 weeks.
RalfKramden is offline  
 


Thread Tools
Search this Thread
Quick Reply: 1989, No crank, VATS/PASSKEY problem and workaround


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: