Dead TVSS Alarm in 1995 LC

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Joined
Nov 19, 2006
Messages
218
Recently I've been parking in the downtown area and was thinking to get an alarm installed. My 95 has the Toyota Security light on the dash and from the posts on the Board, I was able to locate the alarm control module under the drivers seat.

It looks to be the Toyota TVSS model (predecessor to the RS3000 in the LandCruisers). From what I can see, it is fully connected and not modified in any way by a PO. However, it is completely dead -- even the LED on the dash never lights up even if I try the remote programming steps in the manual.

I disconnected the harness to the main alarm module under the seat but was still able to start and run the engine with no problems. I wonder if there is a wiring pin out for the main module connector so I can see if any power is getting to the module. The alarm is acting like it is not even connected with the rest of the electrical system.

If it's not too difficult, I was hoping to trouble-shoot the TVSS system to see if I could get it working since it is already installed and designed for the LandCruiser.
 
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Olathe, KS, USA
Recently I've been parking in the downtown area and was thinking to get an alarm installed. My 95 has the Toyota Security light on the dash and from the posts on the Board, I was able to locate the alarm control module under the drivers seat.

It looks to be the Toyota TVSS model (predecessor to the RS3000 in the LandCruisers). From what I can see, it is fully connected and not modified in any way by a PO. However, it is completely dead -- even the LED on the dash never lights up even if I try the remote programming steps in the manual.

I disconnected the harness to the main alarm module under the seat but was still able to start and run the engine with no problems. I wonder if there is a wiring pin out for the main module connector so I can see if any power is getting to the module. The alarm is acting like it is not even connected with the rest of the electrical system.

If it's not too difficult, I was hoping to trouble-shoot the TVSS system to see if I could get it working since it is already installed and designed for the LandCruiser.
I wouldn't even begin to try to make a 26+ year old alarm system to operate. They are unreliable at best. I would rip it out by the roots then have a new version of an alarm installed, possibly using the wiring harness connectors from the old alarm since many of them were plug and play.

Someone on here has been working on an alarm conversion harness for these, but I don't recall who. Look for it under the RS3000 posts.
 

ATL Cruiser

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Atlanta, GA
You're going to be hard-pressed to find any troubleshooting guides on your TVSS. I know. I went down this rabbit hole DEEP a few months ago when adding keyless entry to my truck. I even bought the TVSS full guide off eBay.

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In the end, I decided to install an RS3200 system instead. Full details on that here:

 
Joined
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Fairfax, VA
because i had some free time i threw this together when planning out a replacement for the TVSS using a modern alarm brain. Ultimately I won't re-use the harness but build a new one, but maybe this will help someone. I'm fairly certain I got it all right.

1675290658541.png
 

ATL Cruiser

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Atlanta, GA
because i had some free time i threw this together when planning out a replacement for the TVSS using a modern alarm brain. Ultimately I won't re-use the harness but build a new one, but maybe this will help someone. I'm fairly certain I got it all right.

View attachment 3236341
This is gold. This doesn't exist anywhere else online. Believe me, I looked.
 
Joined
Nov 19, 2006
Messages
218
Wow, lots of good info and advice. I should mention that my 95 was a mall cruiser at best and spent a lot of years in storage since I have had it. I paid very little for it back in 2009 when no one wanted SUVs because of the high gas prices back then. It is completely stock so I assumed all the wiring should be intact and the alarm should work. If I find the main module is dead somehow, I might look into that upgrade thread to see what I can do. If it is not too difficult, I would like to put in later Toyota alarm if possible.

Thanks for all the informative posts.
 
Joined
Nov 19, 2006
Messages
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Last night I disconnected the main harness at the alarm ECU. With the ignition on, only pins 11 & 12 had 12v and with the ignition off, only pins 11, 12, 24 and 25 had 12v -- everything else had no power or was grounded.

This makes me think the ECU itself is getting power and ground from the harness but still it does nothing. Most likely the ECU is dead. I guessing there are not replacement ECU's of this type out there which is why others opt for later model Toyota alarms or go with aftermarket.
 

ATL Cruiser

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Last night I disconnected the main harness at the alarm ECU. With the ignition on, only pins 11 & 12 had 12v and with the ignition off, only pins 11, 12, 24 and 25 had 12v -- everything else had no power or was grounded.

This makes me think the ECU itself is getting power and ground from the harness but still it does nothing. Most likely the ECU is dead. I guessing there are not replacement ECU's of this type out there which is why others opt for later model Toyota alarms or go with aftermarket.

It probably has fried capacitors from that era. You have a few options.

Rebuild it yourself by using YouTube videos about old capacitors.

Send it out to a rebuilder. It will cost $300-$500.

Look for one on eBay.
 
Joined
Jul 24, 2006
Messages
331
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Fairfax, VA
Last night I disconnected the main harness at the alarm ECU. With the ignition on, only pins 11 & 12 had 12v and with the ignition off, only pins 11, 12, 24 and 25 had 12v -- everything else had no power or was grounded.

This makes me think the ECU itself is getting power and ground from the harness but still it does nothing. Most likely the ECU is dead. I guessing there are not replacement ECU's of this type out there which is why others opt for later model Toyota alarms or go with aftermarket.
you sure about those pin numbers? they don't match my '95 harness, or the other docs from '90.

but yea, mine never worked right. the reset procedure is supposed to generate a horn honk, then allow pairing. nope. the red led did turn on, but that was the only sign of life. yanked it all out and have my eye on a compustar keyless/alarm/remote starter.
 
Joined
Nov 19, 2006
Messages
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Agreed, pin numbers don't seem quite right to me either but, maybe if the components are bad, not sure. I might first try first replacing the dried out components in the ECU, that can't cost too much. Then, I'll go from there based on if it shows signs of life or not. I really want the alarm to work and keyless entry would be nice as well.

btw -- I see videos out there about devices thieves have to defeat keyless entry systems in modern cars. With the TVSS system being so old, I wonder if those same devices are compatible with old alarms.
 
Joined
Jul 24, 2006
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Fairfax, VA
not sure how the TVSS era keyless worked. i'd guess a one-way unencrypted RF signal. with no rolling code like modern garage door openers implemented to defeat similar attacks.

so if a bad guy can capture the unencrypted RF signal from your remote, and replay it, then yes, you are doomed. however you still have the ignition switch to defeat a drive away. you might see the guy in the bushes however as the range on the factory fobs sucked.

my understanding is most modern day keyless systems are now encrypted, but i haven't been able to find much info. i heard that two-ways were less secure as the bad guys could see these beaconing via RF, but i don't know what made them less secure other than some guy said it.
 

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