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Hello everybody. I own a 1985 corvette and want to find and unplug the Theft deterrent module as it has been giving me fits and I don't care to fix it. From what I understand it is up in the passenger foot well near the ecu. It is a black plastic module with a 13 wire plug attached. I have looked and felt up there but don't see it. My 85 does not have a vats module only a theft deterrent module. Does anybody have personal experience with how to find and unplug it. I know I can pull the fuse behind the DIC but from what I understand I will loose my horn function but pulling the plug I will not. Thank you
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by dentalfloss
Hello everybody. I own a 1985 corvette and want to find and unplug the Theft deterrent module as it has been giving me fits and I don't care to fix it. From what I understand it is up in the passenger foot well near the ecu. It is a black plastic module with a 13 wire plug attached. I have looked and felt up there but don't see it. My 85 does not have a vats module only a theft deterrent module. Does anybody have personal experience with how to find and unplug it. I know I can pull the fuse behind the DIC but from what I understand I will loose my horn function but pulling the plug I will not. Thank you
It is lower than the bread loaf. Its bracket is on the front side of the aluminum IP support. It is in front of the ECM and its mount. I don't know if access from the top with the IP Pad removed is possible. Access from underneath is going to be fussy, there's a lot of chit under there on the passenger side.
In a 1985, the starter interrupt relay is Normally Closed. The module Opens the relay contacts to prevent cranking. Disconnecting the module in an 85 won't cause a no-crank or no-start. Nothing hapens with the module disconnected except the alarm doesn't work any more. No more flashing SECURITY light with the doors open either.
I want to thank you for you help on locating this module. I know I did not want to go through removing the bread box and what ever only to not find it. From all the research I have done on this that removing the fuse would eliminate the use of the horn but unpluging the theft deterrent module would allow the horn to work, Do you know if this is true? And again, thank you.. Meanwhile I may remove the seat so better to see up there with a flash light and see what I can accomplish.
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by dentalfloss
I want to thank you for you help on locating this module. I know I did not want to go through removing the bread box and what ever only to not find it. From all the research I have done on this that removing the fuse would eliminate the use of the horn but unpluging the theft deterrent module would allow the horn to work, Do you know if this is true? And again, thank you.. Meanwhile I may remove the seat so better to see up there with a flash light and see what I can accomplish.
If you don't use power locks or door key to lock the car, it's not activated. Shouldn't give you fits anymore
Last edited by Cruisinfanatic; Sep 17, 2021 at 09:48 AM.
Hello again and I want to thank everybody that responded. I spent a week in researching my 1985 Theft deterrent system prior and know exactly how the system works, I have a owners manual and a Service manual and I simply just want to disconnect the plug from the module. I will disconnect it and follow up on how to accomplish this because this is one of the c4 corvette's nemesis that give a lot of owners problems. Again thank you all.
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by ihatebarkingdogs
Well then, you're in the minority here. Many peeps don't, including the original owner of an 85 cruisinfanatic that said that the alarm can be "activated" with the door key. It can not. My post was to correct that error.
If you know "exactly how the system works", why not fix it? It isn't very complicated. I disagree with "this is one of the c4 corvette's nemesis that give a lot of owners problems", because in actuality, there are few reports of "problems" with it (especially in 84 and 85 where the system is in its simplest form) on here that aren't related to either not knowing how the system is supposed to behave, or to the door pin switches becoming corroded which can create false grounds and trigger an armed system. Anecdotal to be sure, but 36 years on, my I-bought-it-new 85 hasn't had a lick of trouble with the UTD, or much else for that matter.
I know exactly how it works and thats why I do not want to fix it because it is complicated and it is a nemesis as proof from hundreds of c4 owners simply delete the system as I found out after many internet searches. I do not think that someone is going bother to steel my $10k 36 year old car. I don't want it need it or ever used it and I have insurance to cover it. Look at all the companies that make delete plug in kits for our c4's. There must be a reason. Not everybody is like you trying to keep up spending money, time and aggravation with something they decided they don't need or want anyway.
Don't get me wrong as I respect your opinion as a purist.
Last edited by dentalfloss; Sep 18, 2021 at 08:41 AM.
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by dentalfloss
I know exactly how it works and thats why I do not want to fix it because it is complicated and it is a nemesis as proof from hundreds of c4 owners simply delete the system as I found out after many internet searches. I do not think that someone is going bother to steel my $10k 36 year old car. I don't want it need it or ever used it and I have insurance to cover it. Look at all the companies that make delete plug in kits for our c4's. There must be a reason. Not everybody is like you trying to keep up spending money, time and aggravation with something they decided they don't need or want anyway.
Don't get me wrong as I respect your opinion as a purist.
You're quoting the wrong person
So why can't you simply just not use the anti theft?
OP - you mention having the FSM Removal/replacement is well covered. In an '85 FSM there's an image for 'location' Electrical Diagnostics page 201 (image 1)
OP - you mention having the FSM Removal/replacement is well covered. In an '85 FSM there's an image for 'location' Electrical Diagnostics page 201 (image 1)
Just read!!!!!
Are you trying to make me look bad. On page 201 shows whats behind the information center. That is not where the Anti theft deterrent module is so you should look again.
You're quoting the wrong person
So why can't you simply just not use the anti theft?
I clicked "quote" in response to article above his post and that is how it came out. You should read above as I do not want to use it and that is why I am disconnecting it. If I lock the doors It arms it. disconnect it and It won't.
Did I miss the part where you explained what "fits" it was giving you? Just curious as to what the problem is.
No you did not miss that part as I never got into that and I just simply asked for someone that had personal experience as to the exact location of the anti theft deterrent module so I could disconnect it. The system needs repair and I do not want to fix it.
Theft Deterrent module location
