Lexus SC Will not crank below freezing temperature

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Last week in 20 degree F weather I experienced this problem with my '95 SC300 (manual transmission, 223K miles). All electrics worked normally until I turned the ignition key to 'Start'. At that point, the dashboard went dark, as it normally does when the starter motor is cranking the engine, but it did not crank. I removed the key and tried again, probably five times, with the same result - no crank. I had driven the car the previous day, in warmer temperatures, with no problem. I connected a portable jump-start battery device, which made no difference. I was able to get by without the car, so left it sit. When the weather got up into the 40s, it started normally, and has continued to function normally in 40-50 degree F weather. So, it seemed to be cold-temperature related. One suggestion I got was that the anti-theft deterrent system might be malfunctioning. Possibly related, in cold weather the built-in car alarm will occasionally go off when I unlock one of the doors with the key. It goes off when I relock and unlock the opposite door, with the key. Also, I have noticed in sub-freezing weather that the door locks will lock and unlock on their own as I drive down the road. Neither is a big problem, but both are annoying. Are these problems related? Is replacing the anti-theft deterrent ECU an effective solution? Is it practical, considering availability, cost, and diffuculty to replace? Thanks for any help!
 

Sulu

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Have you had the battery tested? Maybe it is time to replace the battery.
 
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You know, I thought of that, too. But attaching the fully-charged portable jump-start device made no difference at all; it still would not crank. And the battery shows none of the typical signs of weakness, such as slow cranking now and then. And when the temperature went up ten or so degrees F, the starter spun the engine nicely and it fired right up. So, I think the battery is not the problem. Although, I have not had it tested, which is easy enough to do. I'll do that. Thanks.
 

Ian Schmidt

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I had an issue where the battery seemed fine but the first time that winter it got below 25 degrees F the car wouldn't start at all, so battery failure definitely can sneak up on you. That said, even in that state the car started immediately with a portable jump pack so you may have other issues (although I'm kind of at a loss as to what in the engine would cause that behavior).
 
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Ian, Thanks for your note. I intend to get the battery checked, but doubt that's the issue. Some comments on the Club Lexus forum point towards, if not specifically at, the anti-theft system. Do you know anything about whether there's some susceptibility to cold-weather failure in that system? Maybe it's time to ask the local Lexus dealer, though they have not been much help in the past.
 

Ian Schmidt

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I don't know why anti-theft would care at all about the temperature, but it might be related where the module is mounted or something. I'd definitely consider running it by a dealer and also asking them about your heater problem. Just be firm that you want them to call you with the diagnosis & estimate before they do any work.
 
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I went to the dealer today. No service bulletins on this problem, and no familiarity with it. They never heard of anyone having this problem before. Makes me feel special.

While I was there, the dealer's acquisition manager asked me whether I wanted to sell. Sort of made my day.
 

Ian Schmidt

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That sucks that they couldn't do anything about it.

The acquisition manager probably wanted the SC for himself, those first-gen ones are pretty desirable.
 
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He had never seen one with a stick shift before. Seemed not to know Toyota ever made them. Really lit him up.

Agree that it sucks that they could not address the problem. It's a shame that all the fundamental stuff on this car is rock solid, while the peripheral stuff is beginning to become irritating. Who needs a security system, anyway? Can't wait to see how today's electronically dense cars are working in 25 years.
 
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I have not resolved the problem. The car is now in the shop, though it's tough to troubleshoot when the warmer temperatures here (Seattle) have evidently eliminated the problem. Since the temps warmed up, everything has reverted to normal. The Lexus dealer has no knowledge of any similar problem with these SCs. Do you have any suggestions?
 

Levi

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No, unfortunately I have no suggestions then. Troubleshooting electronic issues is really difficult, especially when the issue is related to some variable factor.

A pity, because I am looking to by a 20 year old Lexus.
 
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