Help For Possible VAT Problem
Thread Starter
Instructor
Joined: Dec 2013
Posts: 155
Likes: 43
From: Federal Way WAshington
Help For Possible VAT Problem
Sorry if this is a question that has been answered many times before but I have spent quite awhile looking on the forum and am just getting confused.
I removed the running gear from my 1988 Corvette and installed it in a 1957 body along with a Painless wiring harness for the engine. I used the 88 column but do not have the VAT module from the 88.
The car doesn't have any spark and is sending a code 46 to the check engine light. I do have 12 volts to the distributor in both run and crank positions and do not get a spark even when the 4 pin connector is disconnected.
I think I need to have my computer reprogramed to eliminate something but I'm not sure what to do.
I looked at all the VAT bypass information but I don't think I have anything to bypass unless it is inside the computer.
I removed the running gear from my 1988 Corvette and installed it in a 1957 body along with a Painless wiring harness for the engine. I used the 88 column but do not have the VAT module from the 88.
The car doesn't have any spark and is sending a code 46 to the check engine light. I do have 12 volts to the distributor in both run and crank positions and do not get a spark even when the 4 pin connector is disconnected.
I think I need to have my computer reprogramed to eliminate something but I'm not sure what to do.
I looked at all the VAT bypass information but I don't think I have anything to bypass unless it is inside the computer.
Thread Starter
Instructor
Joined: Dec 2013
Posts: 155
Likes: 43
From: Federal Way WAshington
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
The ECM will disable the starter and not pulse the injectors.
You've already solved the no crank problem.
To solve the pulsing of the injectors you can purchase a module that generates a 30 HZ signal that you connect to connector 2, pin B6 of the ECM (fuel enable signal).
http://www.ebay.com/itm/PASSkey-II-Bypass-Module-For-LS1-and-LT1-Gm-VATS-/281567207398?pt=Motors_Car_Truck_Parts_Accessories&hash=item418eb69fe6&vxp=mtr
That won't get rid of the DTC 46 from setting but at least you don't have to get the eprom reprogrammed.
Your no spark problem must be in the distributor or wiring. It's not related to the DTC 46.
Do you have a tachometer you can attach to where the factory White wire for the dash cluster tach originally went? (side connector on distributor cap next to the 12 volt wire). If so does it show rpm when you crank the engine?
That would tell you the primary side of the ignition is working and the problem is in the secondary.
Last edited by Hooked on Vettes; Apr 10, 2015 at 03:46 PM.
Thread Starter
Instructor
Joined: Dec 2013
Posts: 155
Likes: 43
From: Federal Way WAshington
DTC 46 is caused by the missing Vats decoder module.
The ECM will disable the starter and not pulse the injectors.
You've already solved the no crank problem.
To solve the pulsing of the injectors you can purchase a module that generates a 30 HZ signal that you connect to connector 2, pin B6 of the ECM (fuel enable signal).
Passkey II Bypass Module for LS1 and LT1 GM Vats | eBay
That won't get rid of the DTC 46 from setting but at least you don't have to get the eprom reprogrammed.
Your no spark problem must be in the distributor or wiring. It's not related to the DTC 46.
Do you have a tachometer you can attach to where the factory White wire for the dash cluster tach originally went? (side connector on distributor cap next to the 12 volt wire). If so does it show rpm when you crank the engine?
That would tell you the primary side of the ignition is working and the problem is in the secondary.
The ECM will disable the starter and not pulse the injectors.
You've already solved the no crank problem.
To solve the pulsing of the injectors you can purchase a module that generates a 30 HZ signal that you connect to connector 2, pin B6 of the ECM (fuel enable signal).
Passkey II Bypass Module for LS1 and LT1 GM Vats | eBay
That won't get rid of the DTC 46 from setting but at least you don't have to get the eprom reprogrammed.
Your no spark problem must be in the distributor or wiring. It's not related to the DTC 46.
Do you have a tachometer you can attach to where the factory White wire for the dash cluster tach originally went? (side connector on distributor cap next to the 12 volt wire). If so does it show rpm when you crank the engine?
That would tell you the primary side of the ignition is working and the problem is in the secondary.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The starter enable relay is connected directly to the VATS module in a normal Corvette configuration. The ECM has nothing to do with disabling the starter.
To solve the pulsing of the injectors you can purchase a module that generates a 30 HZ signal that you connect to connector 2, pin B6 of the ECM (fuel enable signal).
That won't get rid of the DTC 46 from setting but at least you don't have to get the eprom reprogrammed.
That won't get rid of the DTC 46 from setting but at least you don't have to get the eprom reprogrammed.
Thread Starter
Instructor
Joined: Dec 2013
Posts: 155
Likes: 43
From: Federal Way WAshington
Thanks for all the help. I must confess that I feel really stupid but when you mentioned the primary circuit it occurred to me that I had only connected the 12 volt connector to the distributer cap and then plugged in the 4 pin connection. Fishing around under the distributor I found the other connector that plugs into the cap and now the car starts and runs for a second then shuts off due to the VAT system. I ordered the bypass and that should take care of that. I would like to have been able to blame the lack of spark on something other than my stupidity but it is what it is. Thanks again for your help.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Based on your earlier posts, you do need a VATS bypass module to get the ECM to pulse the injectors.
Last edited by Cliff Harris; Apr 13, 2015 at 12:50 AM.
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Thread Starter
Instructor
Joined: Dec 2013
Posts: 155
Likes: 43
From: Federal Way WAshington
The bypass that I ordered is for cars that no longer have the VAT module and it should keep the fuel pump running and pulse the injectors but if that don't solve the problem then I will check out the oil pressure senders etc.
Thread Starter
Instructor
Joined: Dec 2013
Posts: 155
Likes: 43
From: Federal Way WAshington
Just as a follow up for anyone else that has this problem I installed the VATS bypass module purchased on eBay for less than $20.00 including shipping and the car started and runs great.
Thank you all for the help as this is all new to me and I felt a little lost until you pointed the way.
Thank you all for the help as this is all new to me and I felt a little lost until you pointed the way.