shaw289

I have an 85 Vette that I am working on. One day it shut off and the security light is now blinking and it will not start. It will turn over and if you hot wire the fuel pump it will start but it will not stay running cause the VATS has the fuel injectors shut down too. I've read about the resistors you can put in the wiring to bypass the VATS system but I can't find the 2 wires in the steering column that everyone says to splice them into. It was running perfectly fine before the security light started blinking. Anyone have any suggestions? Thanks!

VikingTrad3r

are you sure its an 85?

they dont have vats.

does the key have a resistor on it.


there was something about a theft deterrent system on 85 but it wasnt as sophisticated as vats.

shaw289

Yes it's definitely an 85. No it does not have a resistor key. Some places I read that they had it some places I read that they don't. Wether it's VATS or a theft deterrent system it didn't do this until the security light started flashing

VikingTrad3r

if u have the fsm i think there is a troubleshoot process for that condition

shaw289

I went through all the troubleshooting steps in the fsm. Still no luck

VikingTrad3r

check out this thread.

https://www.corvetteforum.com/forums/c4-tech-performance/2396578-1985-won-t-start-vats-theft-deterant-2.html

VikingTrad3r

actually if your turning over i dont think its your issue.


1. pull codes using paperclip method?


2. check fuel pressure with key on. note if it bleeds pressure off.

shaw289

How do you do the paper clip method. I remember reading about this before but I don't think I did it right

WVZR-1

Do the horns work NOW? Did they work prior to your recent attempts at repairs? What were you working on? Theft is also powered by I believe the in-line horn fuse. Treat maybe the SECURITY as a different issue for diagnostics and deal with it first. There's reset procedures I'm sure for it in the FSM. Try the RESET procedure in the FSM 1st maybe.

The ECM in '85 is a "one year" build and I believe it actually has a "fuel pump on" requirement to run. Jumper maybe the OPS and try OR maybe just do B+(12V) directly to the G terminal on the ALDL and that should I believe turn pump on and provide TURN ON the ECM wants to see. You said it cranks and runs "momentarily"!

Much maybe depends on WHAT YOU WERE ATTEMPTING TO REPAIR when the SECURITY light came on and the run issue followed. Fuel pump relay is a possibility!

ON 8TH

Make sure the doors,hood, hatch are totally closed. Lock the doors with the key.Open the drivers door with the key. Then try & start it .

shaw289

Tried this and that did not work

shaw289

Not sure about the horn. Never tried it. That's a good question. I really wasn't doing anything to it when it stopped. I just moved it from my back garage to my front garage and it shut off on me and would not start after that. I'll try the OPS and see what happens. As far as the ALDL, are you saying jump terminal B AND a 12v to terminal G?

Hot Rod Roy

If the Security light is blinking, I believe the horns should be honking. Can you hear the horn relay clicking behind the center panel of the dash? Something strange here. Is this your car, or are you working on a car with unknown history? Try disconnecting the battery for about 30 seconds to reset the alarm.

That's true. No VATS in the '85.

shaw289

I bought the car 2 years ago. I've set the alarm off before so the horns did work at one point. Not sure if they work now since it stopped running. The horns don't have to be honking when the security light is flashing. I have unhooked the battery many times. Still flashes

WVZR-1

Just put 12V jumper to G in the ALDL and the pump should run, take the 12V directly from the battery if you like. Do NOTHING with any other terminal - 12V to G in the ALDL. How fast does this car crank? Labors to crank off battery OR at full charge cranks as expected?

***You mention starts - runs a few seconds and dies. Maybe ignition module failing and no distributor reference so ECM isn't energizing the fuel pump relay.

shaw289

Ok thanks! I'll give that a try. It cranks over like it should

ON 8TH

ok,if it starts & wont stay running,check the oil pressure sender,if the ecm doesn't see oil pressure it shuts off the fuel,safety measure in case of accident etc.

VikingTrad3r

OP uneed a fuel pressure gauge. they are cheap.

see if its pressurized.

if you find that it is pressurized, we can move fwd.

wich is the part wvzr1 said about icm in dizzy

Cliff Harris

NOT true. The oil pressure switch is in parallel with the fuel pump relay. It is there in case the fuel pump relay fails.

Cliff Harris

SECURITY light modes (TDS (Theft Deterrent System)):

Flashing - system is NOT armed, door is open
On solid - system is armed, door is open
Off - door is closed and/or ignition is on