Taka

Hi, my keyless entry is not working and I have quick question.

If I change receiver ECU, can I just get ROM chip and change it? or I have to change ECU and reprogram whole key sets. anybody has changed ECU/ROM before? let me know, thanks

Key doesn't go smoothly in the driver side key hole, it's getting annoying. so I'm considering getting after market security system with keyless entry or just change stock ROM if possible.

Camshaft

Go to your local hardware store and get some dry carbon lubricant. Use a nail or something to push away the little shield that pops down inside the keyhole, and squeeze a little in there. Carefull, alot comes out. One or two good squirts should cover it. That stuff will unfreeze any lock. Should cost you a couple of bucks, and is considerably cheaper than buying a new Viper system.

Can I go to Radioshack and buy a new chip for my remote? Anyone? I think I am going to try if no one replies, can't hurt anything.

933005spd

I have been trying to hack the lexus sc security system for some time now. My main goal is to integrate some more functions to the simple key such as beep on arm, 2 on disarm, trunk pop on 2 pushes etc...

Anyway to answer your question, you will need a new key and ROM if your rom is failed. But first you should check many things:

- antenna connection. Alarm gets signal via defogger wire, the inline capacitor can fail as can the connection.
Try activiating the alarm with the tip of the key touching the door key cylinder.

Try activiating the alarm with the key inserted in the antenna plug on the ecu, do not let the key come in contact with the case when you push the button.

- The manual has all the required VOM tests to evaluate the ecu.

Buying and cutting a new key/rom is expensive and may not fix the problem unless you are absolutly certain nothing else is malfunctioning.

933005spd

The chipset on the key transmitter is: ND MR257, 03M20A

Taka

Thanks for info,
chipset you are talking about, is it one inside they key or one inside receiver ECU (ROM)?

When I have time, I'll take out rear seats and check ECU and rear speaker(making rattle sound).

Camshaft

Okay, I couldn't find the ECU for the keyless entry. Can you help me out?

Taka

Camshaft, what happened to your keyless entry? not working either? there is troubleshooting before taking out ECU.
http://pub4.ezboard.com/fladmanlexus...icID=906.topic

my problems is probably ROM defective or ECU.. in this case, I guess I need to get new transmitter and ROM for ECU. I dont think it's worth. I'm planning to install aftermarket KEYLESS ENTRY(only) but I dunno how hard it's gonna be, anyone done it before?

anyways, Camshaft, back to your question.
Wireless Door Lock ECU is located inside RH quarter trim panel(by rear passenger side window).
You have to remove rear seat at first.(there's thread about HOW TO REMOVE REAR SEAT in sc forum) and then you can remove RH quarter trim panel. you can access ECU from there.

Let me attach ECU and ROM(inside ECU), sorry it's not good picture.

Taka

awwww I always forget to attach pic

Taka

I just opened the key transmitter, it says ND MR257, 01N20A.

933005spd

I belive the last few digits identify the frequecy range assigned to the device. These should be unique among the vehicles, but the same in your keys.

If the steps above did not yield any results then the next step is to check voltages.

When you manually lock the doors, does the red led light up in the dash?

Taka

933005spd , for security system LED right? yea it does light up when I manually lock the door.

Camshaft

My keyless entry has worked once, fortunatly in front of a hottie. None since then. The red light does blink when locked with the power locks, I have not checked with the manual method. It chirped also. Strange, being a 92.

933005spd

Taka, the instructions you linked are good.

I suppose you ran those tests I recommended earlier? No positive results?

Try tuning the radio to 94.9 Mhz and check to see if there is radio noise while the transmitter switch is pressed.

The light coming on if you manually lock makes me belive the lock unlock switch and detection switch are all working correctly. I would then focus on the wireless door lock main switch, the door open detection switches and of course the antennea connection, esp the capacitor connection.

Camshaft

What is the gimmic that you have to do to have an aftermarket alarm and keyless entry installed? I know there is a glitch somewhere.

Camshaft

Okay, need some directions here. My keyless does work. Sometimes. It has worked twice in the last week, so I know the ECU is fine. However, I tore out my back seat (discovering how easy it was!) and sub cover and could not find where the keyless anntena is (I know its connected to the defogger wire) other than behind the back pillar where you can see a metal strip through a gap. Is that the place where I should look? I forgot the frequency at which to test, but I wiggled all the wires going to the ECU and no effect. Battery in the key is fine, and it is cleaned out.

In me tearing out the sub cover I discovered that the sun has made the plastic really brittle. Anyone have a spare sub cover laying around?