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lexpert
lexpert, Lexus Master tech
Category: Lexus
Satisfied Customers: 2100
Experience:  Master Certified with lexus, 8 years experience with Lexus
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01 GS430, memory presets can be set and operate properly

Customer Question

01 GS430, memory presets can be set and operate properly after setting. But after leaving car for more than a few minutes, the settings disappear completely. What is causing it to lose the settings, even though I can set them successfully over and over?
Submitted: 1 year ago.
Category: Lexus
Expert:  Skyvisions replied 1 year ago.

Does the clock reset to 1:00 also?

Customer: replied 1 year ago.
No, everything else stays properly set (clock, radio, etc). Just the memory settings (seat, steering tilt, mirrors) disappear. Interestingly, when I put the key in the ignition, the steering wheel tilts/telescopes to the correct position (where it was last left), but the memory functions are completely gone - if I move anything out of position and then hit the previously programmed memory, nothing happens. But again, it DOES stay programmed correctly and returns to the programmed locations if I try it without leaving the car for more than a few minutes.
Expert:  Skyvisions replied 1 year ago.

Ok let me look at the wiring diagrams to see if there is something common between all of these things and I will get back to you this afternoon.

Customer: replied 1 year ago.
Thanks!
Expert:  Skyvisions replied 1 year ago.

Does the dome light work? Do you have the MARK LEVINSON radio option?

Customer: replied 1 year ago.
on both questions.
Expert:  Skyvisions replied 1 year ago.

The only thing that you have in common in these items that are losing the memory is the 15 amp number two radio fuse This is the accessory position and the causing the memory to erase if that fuse is not supplying power. Is it blown and does it have 12 volts to it? It is located in the left kick panel junction block.

Customer: replied 1 year ago.
I will check and get back to you.
Customer: replied 1 year ago.
I swapped in a different 15A fuse into the Radio No 2 location (fuse #11). It made no difference - it retains the memory for about 2 minutes, but after 4 minutes it's gone.i don't have access to a voltmeter right now (I'm out of town), but can check in a couple of days to see if the fuse is getting power. I'm not optimistic about that part, why would a fuse not get power? But I will check.
Expert:  Skyvisions replied 1 year ago.

That 15 amp radio number two fuse and the dome light fuse are the two fuses that control power to the radio unit to retain the memory in the system and also for the memory of the seat position. Because the dome light works that confirms that the dome light fuse is not the problem and unless there's no power at that 15 amp number two radio fuse which would be unlikely but needs to be checked there's not much more I can do for you. If both of these fuses are good you may have an intermittent power supply problem in the wiring harness somewhere between the fuse and the radio itself causing the memory to lose its preset stations. I will opt out at this point so that if there are other experts that have run into this before they can assist you further.

Customer: replied 1 year ago.
I will confirm the voltage at the fuse on Monday and report back. I'm suspecting it's some kind of a fault in an ECU, but with so many ECUs in the car, I wouldn't know where to start.
Customer: replied 1 year ago.
I am getting battery voltage at the fuse. But now that I had a chance to look at the the service manual, it says that the Radio No 2 fuse only has power with the ignition in "on" or "acc" - so are you sure that this is the fuse that retains memory when the key is not in the ignition?
Customer: replied 1 year ago.
OK, Radio No 2 fuse controls the navigation and AC system, not the seat memory. Anyone else out there who can help?
Customer: replied 1 year ago.
For anyone coming across this discussion, don't follow the advice given above. The seat memory is NOT controlled by the Radio No 2 fuse. It is controlled by several other fuses, which also provide power to the seat ECU which is under the driver seat. I followed the wiring diagrams in the service manual and eventually traced the problem down to a bad connector or a bad seat ECU. Just before I ordered a replacement ECU, I looked very closely at the connectors and found a bent pin. It just happened to be the pin that provides power to the ECU when the ignition is off. That's why all the seat functions worked, except for the memory retention. I straightened the pin and the memory works perfectly again.

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