Help! VATS bypassed still wont turn over

[Rokin]

Hi.. I have an intermittent problem where the car wont turn over (maybe 1 in 15 times)..

I can tell when its going to do it because the security light goes from flashing to solidly on when I turn the key to the first stop on the ignition, (normally it goes out when all is ok).

I've already bypassed the VATS wires from the ignition and I don't realy know what to try next.

Can someone point me in the right direction cause I'm realy annoyed and very close to taking a sledgehammer to it. ad

 

[Hib Halverson]

Hi.. I have an intermittent problem where the car wont turn over (maybe 1 in 15 times)..

I can tell when its going to do it because the security light goes from flashing to solidly on when I turn the key to the first stop on the ignition, (normally it goes out when all is ok).

I've already bypassed the VATS wires from the ignition and I don't realy know what to try next.

Can someone point me in the right direction cause I'm realy annoyed and very close to taking a sledgehammer to it. ad

Rather than a sledgehammer, may I suggest the Factory Service Manual and it's VATS diagnostic information?

 

[Bronze85]

How did you bypass it? Did you measure the resistance of the key?

 

[Rokin]

I dont have a factory service manual im afraid (im in the UK not even sure where to get one).

To do the bypass I found the orange wire with the 2 smaller white wires inside that lead from the ignition switch.
There was a connector a few inches from the ignition so I disconnected the wire at this point.
I then connected the 2 white wires via a couple of resistors that add up to 9.53 ohms (I got the 9.53 from info found on the net, when I measured my keys pellet the resistance was 9.54).

 

[88C4]

Ebay is always a good source for used shop manuals.

 

[TedC]

Rokin,
A VATS bypass is not the best description. All it does is bypass the ignition cylinder contacts with an inline resistor of the same value as the key's pellet. The theory goes, if the key's pellet (resistor) fails to make contact in the cylinder, then the VATS system sees the wrong resistance when cracking, and the VATS system prevents engagement of the start relay and tells the ECM not to pulse the injectors. GM should have corrected these issues via a recall, so a VATS bypass should not be needed. A VATS bypass does NOT bypass the VATS system. The rest of the VATS system is still being used and must work properly. This includes the VATS controller and the VATS start enable relay. As pointed out above, you really need the FSM to pinpoint the failing component. My 1988 had intermittent starting until I replaced the VATS start relay which required taking the dash apart.

 

[Old Vette Guy]

Hey Rokin,

I had the same problem with my 88 Vette. TedC is right. Basically, the VATS module, sends info to the computer. If the right info is not being sent from the VATS module, to the computer, it won't start. Tried the bypass, nothing. Ended up replacing the Vats module. When you get a new VATS module, make sure you order one that will work with your ignition key.
Good luck.

 

[Rokin]

Dont know if this is useful but I checked the error codes today and got 2 historical errors:

Module 1 - H51 & Module 4 - H46

I think this means CCM - Invalid Key & ECM - VATS circuit fault.

I'm probably going to check the connections to the CCM next.

Am I right in thinking the CCM is placed conveniently in the depths of the dash behind the heater controls on a 1990 ?

 

[Hib Halverson]

I dont have a factory service manual im afraid (im in the UK not even sure where to get one).

(snip)

You can order a Factory Service Manual from CAC sponsor, Zip Products. They ship worldwide.

As "TedC" has suggested a "VATS bypass" only substitutes a fixed resistor for the resistance in the key. It is not a solution to a problem with grounding, wiring harness or the CCM. Problems with wiring and connections or a dirty key resistor pellet are more likely than a problem with the CCM itself.

My advice is, once again, that you get the Service Manual so you have it's diagnosis instructions and repair procedures. It might be difficult to fix this problem by trial-and-error mixed with anecdotal information from the Internet.

 

[Old Vette Guy]

Dont know if this is useful but I checked the error codes today and got 2 historical errors:

Module 1 - H51 & Module 4 - H46

I think this means CCM - Invalid Key & ECM - VATS circuit fault.

I'm probably going to check the connections to the CCM next.

Am I right in thinking the CCM is placed conveniently in the depths of the dash behind the heater controls on a 1990 ?

As I said before, you need to replace the VATS module. If the VATS module is not sending the "ok to start signal to the CCM, your Vette will not start.

Yes, the CCM and the VATS module are in the depths of the dash, on the passenger side.

 

[vetteoz]

Am I right in thinking the CCM is placed conveniently in the depths of the dash behind the heater controls on a 1990 ?

As I said before, you need to replace the VATS module. If the VATS module is not sending the "ok to start signal to the CCM, your Vette will not start. .

No standalone VATS module on '90+ ; is integrated into the CCM

 

[vetteoz]

I'm probably going to check the connections to the CCM next.

Bypassing CCM to Enable Starting - Corvette Forum

 

[Hib Halverson]

As I said before, you need to replace the VATS module. If the VATS module is not sending the "ok to start signal to the CCM, your Vette will not start.

Yes, the CCM and the VATS module are in the depths of the dash, on the passenger side.

Only thing is...on a 90, there is no "VATS module".

I suggest that those giving advice should familiarize them selves with the model year in question rather than just assuming the VATS on all C4s is the same.

The first step is to diagnose the two fault codes per the diagnostic info in the FSM then make repairs accordingly. Not only will the Service Manual help you diagnose, but it's drawings will help you find the location of and understand how to replace the CCM, if it's required.

A faulty CCM is only one solution to those codes. It is quite possible there's no problem at all with the CCM, rather the trouble is with wiring and connections. I'd check them first.

Lastly, it's interesting that this thread has gone on so long without anyone suggesting the problem might just be a dirty resistor "pill" in the key. Has the key been cleaned off thoroughly?

 

[vetteoz]

Lastly, it's interesting that this thread has gone on so long without anyone suggesting the problem might just be a dirty resistor "pill" in the key. Has the key been cleaned off thoroughly?

Only because he stated 1st up he has bypassed the VATS
Maybe his connection is bad on the resistor?

 

[Rokin]

Thanks Guys.. Very helpful.. especially the pic of the CCM..

The way I'm thinking is.. I've bypassed the ignition with resistors, so that leaves either the CCM or the 'starter enable relay'.
As the security light comes on when this happens and I have a H51 code stored, Im pretty sure it must be CCM related.
So I've ordered a proper VATS bypass from Eklers (just in case my resistors are flakey), and I'm going to clean all the connectors leading to the CCM. If that fails I guess im looking at replacing the CCM.

Might it be easier to get a new chip for the ECM with the VATS removed, they dont seem to be too expensive, its a five min job to replace it, and I'm not worried about the security as I have a TOAD alarm/immobiliser fitted ?

Last thing.. I need a new radio (CD players packed up on mine), thought I might as well do that at the same time. Is it possible to get hold of an original second hand one or a reproduction of some kind ?

 

[sweabe]

For the Radio issue, contact GTE Industrieelektronik GmbH. They did my Radio, replaced the CD unit with an OEM unit (reads CDR)

//sweabe

 

[92LRC]

Hi.. I have an intermittent problem where the car wont turn over (maybe 1 in 15 times)..

I can tell when its going to do it because the security light goes from flashing to solidly on when I turn the key to the first stop on the ignition, (normally it goes out when all is ok).

I've already bypassed the VATS wires from the ignition and I don't realy know what to try next.

Can someone point me in the right direction cause I'm realy annoyed and very close to taking a sledgehammer to it. ad

Check the stater enable relay.
Also look into this site

VATS Sucks . com

almost any information regarding VATS can be researched here.

Take a look here also for more info

http://forums.corvetteforum.com/c4-...ing-i-thought-i-had-the-vats-bug-fixed-2.html

Good luck