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3TXA - 3TXB - 17TN Fobs: Common Faults

103K views 100 replies 47 participants last post by  david.anthony 
#1 ·
The 3TXA, 3TXB and 17TN fobs all suffer from common faults that will render a once working unit inoperable or with intermittent operation.

The 3 circuit boards are similar, the 17TN fob has a more robust design and is the less troublesome of the 3.

Here are the 3 circuit boards....





The most common fault is to do with the battery holder and how it is soldered to the circuit board. There are 3 legs and they are soldered on both sides of the board, various sections of the circuit take power from different legs, thus all six joints need to be properly soldered.



If the legs need to be resoldered remove the battery and press the holder towards the board while soldering, this ensure that the battery is held tightly and makes good contact.

Here are some pictures of "dry jointed" legs and will give you a good idea of what to look for...








The 3TXA and 3TXB fobs use a canister type crystal for the clock signal, ideally this should be glued to the circuit board but it is only held in place by it's two wire leads. It's common for the wire to fracture where it has been soldered to the board.




Sometimes the two tact switches can fail on very old fobs, they can be replaced with new items. Generally though the soldering fails and one or more of the switch "legs" becomes dry jointed...

 
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#2 ·
please help... 3TXA fault

could some one tell me what is the part number of the transmitting crystal in this 3TXA fob.
my 3TXA stop working, when i opened it i found that the crystal is broken from the extreme edge that i can't resolder it again then i lost it and i don't know the part number....can some body help me to restore my 3txa fob again... i'm sick of opening the doors by the key.

thanks
cheers
 
#14 ·
key fob rubber button

hi, i'm from malaysia. do you sell the rubber button that is fixed to key fob that covers the button? if not, do you know where i can get them? i do not mind the postage, as i have to buy a complete new set even if only the rubber cover is broken. i am looking for 2~3 pieces. i can pay via pay pal.
pls advise
thanks
qinzir
 
#17 ·
So can the 17TN fob be used in place of a 3TXA? (i.e. do they all work on the same frequency and just require coding to the car?)

THe problem I have with my fob is that the lock button works fine, but the unlock doesnt. If you stand and keep pushing the unlock button it eventually opens. If you spilt the case and directly press the (yellow) button on the circuit board then it is fine. (New Battery and fob case/re-furb kit fitted)
Tia.
 
#18 ·
Hello technozen ive got a 3txa fob from my 200sx, me being the fool i am dropped my keys and my fob doesnt deactivate my immobiliser, i noticed all the fob is fine and it doesnt require soldering. but if i rattle the fob i can here a noise, i think the transmitting crystal has broke, is this common at all? and is there anychance you know where to buy them from? cheers
 
#21 ·
Alarm System Trouble

My R Reg 216 key fob went temperemental last week, then died last night. Alarm bypass code techniques in the manual don't work. Attempts by RAC man to fix ended in key fob opening doors and turning off alarm light as desired, but engine still completely immobilised when ignition turned. Seems the alarm control unit (is that what they call it?) is fried on mine this time (I replaced the key fob wusscessfully when last one went temperemental). Any ideas on a cheap fix in London...if those words can ever go together!
 
#24 ·
My R Reg 216 key fob went temperemental last week, then died last night. Alarm bypass code techniques in the manual don't work. Attempts by RAC man to fix ended in key fob opening doors and turning off alarm light as desired, but engine still completely immobilised when ignition turned. Seems the alarm control unit (is that what they call it?) is fried on mine this time (I replaced the key fob wusscessfully when last one went temperemental). Any ideas on a cheap fix in London...if those words can ever go together!
Terry of T.S.Autos in the R75 section may be able to answer your questions. Give it a try cos you've got nothing to lose.


Colvert. :broon::broon::coffee:
 
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#29 · (Edited)
Rover 200 diesel 1994 cm^3




technozen, I need your help in troubleshooting the engine's immobilizer alarm system...
I own a ROVER 200 series, model 220 SDi, year 1998.
I'll tell the whole story happened...
Last week, as I went back home from work on evening, parked my car outside my house and locked the doors as usual with the key-fob but noticed that turn indicators don't flash. First I tried to unlock the doors with the unlock button but it doesn't work. So I decided to unlock doors manually with the key. Since then the engine's immobilizer stood inserted although I tried several times to re-synchronize the alarm. I have the 2 keyfobs checked and found the dry-soldered joints that you show in this thread, have re-soldered all bad joints, have checked all the connections with a tester, then checked in A mode the output current from the CR2032 battery when the lock or the unlock button are pressed and read for both buttons a current of about 1 mA which suddenly falls to 0 after 1/2 second while one of the 2 buttons is pressed. Is this a signal that the keyfobs are working correctly?
This failure occurred a few other times during my car's life (12 years!) but the other times I found that the problem was in the button switch in the housing of the right rear car's door, have it disassembled, checked and cleaned then reassembled in his housing and finally the alarm could be deactivated by the keyfob. But in this case this solutions doesn't work. Now I'm trying to disassemble all the other contact sensors in the 4 doors of my car. My car have 5 doors, is there a contact also in the rear luggage port?
I tried obviously to disinsert engine's immobilizer by writing the code with the key combination (eka code), but it has no effect. Do you think the 5AS alarm security system is really dead in this case? If so, where is it located in the car to reach it for maintenance? And can it be deactivated in some way to avoid its sostitution because car is very old and I don't want to spend money, I prefer to lock the car's doors with the key instead of installing a new alarm system... Last question I would like to ask is: If I disconnect car's battery leads, is this useful to reset immobilizer's alarm system?

Finally, I'd like to add these additional informations:
I live in Italy and purchased my ROVER 200 here, so it has steering on the left seat side.
It has a turbo-diesel engine with a displacement of 1994 cm^3 that equals to 121,68 in^3.

Any answers which can solve the problem be appreciated.
Kind regards.

TRUEFOLIX
 
#30 ·
There are alarm switches on all doors, the boot and the bonnet.

If these are faulty they will stop the alarm from arming but will not stop the central locking from operating or stop you from disabling the immobiliser.

Having read your description the first thing I would suggest that you check is the tailgate wiring loom for shorted wires.
 
#31 · (Edited)
Thank you very much, technozen. I just read your answer, when I have a bit of time will check the tailgate wiring loom for any shorted wires.
In fact there could be something bad in the tailgate because 3 months ago an 455h0l3 invested my car in the back while reversing with a Volvo SUV, the tailgate was dented, the plastic with ROVER logo broken and the logo lost. In addition there can be wipers pipe broken inside the tailgate loom because water doesn't come out from the rear wiper.

I disassembled the steering block and saw the loop antenna coil of the receiver, I think it is in good condition. There's a little lamp on the steering key block which is blown and I can change it with a new one. Checking the fuse box under the bonnet i found the centralized locking one blown but inserting a new one made the alarm horns ring. So it can be some wire shorted/interrupted in the rubber tunnel connecting the body with the tailgate, as you told me before, that makes the alarm ring. In fact those wires are subject to stress during opening and closing of the luggage port and very easily they can be broken.
 
#32 · (Edited)
Hello guys, which type of equipment is used for programming new fob on Rover 200. Is that some special type of tool or it can be done with any type of diagnostic tool that works on Rover. My father in law tried to clean his 3txa remote and he destroyed it. Button switch and oscillator are ripped off. Some electrician soldered him button switch but was unable to solder oscillator because leads are ripper off. But together with switch he soldered one lead of component that look like transistor to antenna (marked with red line, technozen i have used your picture to show it :) )

I have remove that soldered connection and soldered new 32.768khz oscillator but fob is still dead. Maybe that processor 15101 is dead now.
Here where we live Rover is not very common car and we don't have dealers that work with Rovers. It would be helpful for me to know what is used for programming new fob to alarm so we could easier find person that has that tool.
Thanks
 
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