Theft / Security control module 89730-50011 replacement

[Gmach]

This is for a 1991 LS400. Has anybody replaced one of these yet?

If so, can you tell me if it needs to be programmed by Lexus before it will work in the car.

They are no longer available from Lexus so I would have to buy one on line, used.

Also, where is it located and is it hard to remove / replace.?

Thanks

[sha4000]

I think it's behind the glove box.

[Exhaustgases]

I think it is more towards the center of the dash, not sure and too lazy to run and look right now. There is no reprogramming that I know of, because there is nothing to program it too. And keep the old one it maybe fixable.

[Gmach]

We tried to open the car with the key fob that broke in my hand and stopped working. The key tumblers on both doors are jammed so couldn't use the metal key. Called for a towing service who used a wire to unlock the door from inside..pulled the pin up. Then, when I tried to start the car it just went "click / click" and nothing. Had it towed to a Lexus dealer who said, after testing,  that module is "fried". Obviously we needed a new key so had to order one. The dealer is 100 miles from home so I asked them to try the car with the new key they said it won't start without that module being replaced and re coded....so I'm confused! Any ideas? It seems odd that module suddenly broke simply because we jimmied the door. Is it fair to assume the car has gone into some sorta security setting because of the way be opened it? Shouldn't the replacement key re-set the security system?

[Exhaustgases]

The car is a 91 right? The dealer must think its a 95 or 98 or something like that. If the module is bad replace it. There is nothing to reprogram in the old days. What intercommunication there is between the modules is a set thing and not adjustable, things were easier then.

The key transmitter needs to be programmed to the receiver in the trunk for the remote it is a separate deal from the security system.

I say the module is good. If your door locks worked then you could follow the procedure in the owners manual to reset the security system.

So get the door locks and switches to work and then try the procedure, there is very little other than maybe the capacitors that go bad in the engine control ecu could also go bad in the other modules as well. Don't throw the old module out if you replace it. If it truly is the problem it likely can be fixed cheaply.

 

Okay looked in the book. The module looks to be above the interior fuse box or to the right of it possibly near the steering column.

There is an extra horn near the right hand hood hinge that is for the security system, and of course all the door switches are part of it, meaning the key switches and dome light switches etc.

[Gmach]

Thanks for the reply. I had the car towed home. The battery was dead so I put it on the charger. Tried to start the car this AM and it started. Now, since I had to purchase a new key from Lexus, it came with a new chip for the remote receiver in the trunk. Installed the chip and tested the door locks with the remote key..... but nothing! The doors will not lock with the new key. Is there something else that needs to be programmed to the new chip? The locks all work normally when using the manual switches in the car. Could this failure of the new remote key to work also be related to a bad security module...or could the receiver ECU in the trunk be bad? The Lexus dealer did say their scan should that the security module 89730-50011 had a dead short for the starter relay when the car wouldn't start, just clicked....yet the car does start now. But we now seem to have a parasitic drain on the battery. Any ideas what we need to get the remote (NEW) to waork?

[Gmach]

....I'm wondering if that's how the security module works. It creates a dead short at / to the starter relay so the car won't start and that is what the scan saw.

[Exhaustgases]

I think what the security module does is OPEN the starter solenoid circuit. No reason to have to short one side, but could.

The key deal. Only a lock smith or dealer can do what it required to set it. And the reason why is the information to do any of the security related stuff like that and the radio is only allowed to dealers and qualified lock smiths. That is posted on the Technical information site at Toyota. We all can pay for access to all the other information, just not the security related stuff. So either you need a person that knows how to deal with it or do the above.

[Gmach]

So, even thought this is a '90 / '91 LS400 with stone age technology it still needs to go to the dealer even though we got a new key and ROM from them..for some outrageous amount of money...we need to pay more for them to do what... ?

[Gmach]

19 hours ago, Exhaustgases said:

I think what the security module does is OPEN the starter solenoid circuit. No reason to have to short one side, but could.

The key deal. Only a lock smith or dealer can do what it required to set it. And the reason why is the information to do any of the security related stuff like that and the radio is only allowed to dealers and qualified lock smiths. That is posted on the Technical information site at Toyota. We all can pay for access to all the other information, just not the security related stuff. So either you need a person that knows how to deal with it or do the above.

Thanks Bob...but tell me, if we buy a key from Lexus (which we did for $400+ dollars) and get the new key with ROM for the door opening receiver module, isn't that all that's required? Putting the ROM in the module and the new key with the new ROM correctly installed in the module (89741-5005) should activate the door locks...correct? No further trips or ransom money paid to Lexus to get the remote door function on the key to work. I ask because the remote still doesn't unlock the doors after the new ROM installed. Tested the key transmit on FM 94.9hz...it works! Locked the doors from the interior then put the key in the ignition / removed it then cycled the master lock control on drivers door x10...locks cycled once, automatically, so it's in diagnostic mode. Pressed remote button on key..NOTHING! Stuck the metal part of the key in the module antenna port and pressed remote button on key..NOTHING. So, it looks like the remote transmit function on the key is working...problem isn't the antenna. All that is left is the module itself ...which is a strange coincidence 'cause it worked just fine before we had the local AAA guy break into the car when the key broke and stopped working.....but maybe...maybe that's why we couldn't open the door in the first place...the module stopped (89741-50050) stopped working !!! Hmmmmm. It could be that unless we still need to make a trip to Lexus after getting the new key and ROM installed....do we?

[Exhaustgases]

Bri , I guess I need to study the books on it. I haven't played with it and didn't know about the diagnostics etc. I did look at the body collision book and shows the module locations better for the security module. It looks like its above the interior fuse box.  And the door lock module is back near the radio antenna stuff. You maybe right about the module, I don't know.

[Gmach]

I ordered a replacement door lock module on ebay...pretty cheap. I'll let you know if makes any difference. Unfortunately ebay is a crap shot at the best of times.