LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

1997 LS400 170K miles, Coolant Leaks, alternator not charging, ...

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Old 08-12-16 | 05:19 PM
  #76  
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If you look at photo 1 the minus sign is out side the circle just like the one Yamae pointed out and is on the trace that the cap connects to. Also the brown cap in picture 1 is connected the opposite direction of the sign, but can't see the whole board so don't know. If its not working then the polarities must be messed up. Now you need pictures from an untouched board to know whats going on if you can't trust the signage.
Old 08-14-16 | 12:12 PM
  #77  
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Dicer, Thanks for your reply. The polarity of the capacitors is correct. Please refer my response to Yamae: "Thank you sire, Yamae for your prompt reply. I think the polarity is correct. I made sure the polarity of the capacitor match the old one when I was replacing the capacitors. In fact, I found all capacitors on the ECU have their negatives pointing to one same side and the positives point the other same side. The positive sign you saw was for the C131 (the smaller blue one). I do have a question on the repaired trace. The repaired trace has about 25Ohm, where the original copper trace has almost 0Ohm. Would that cause a problem? This trace gets the power from the battery."
Old 08-14-16 | 07:24 PM
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If the smaller blue one is not an electrolytic, then it does not require polarity, if that is the case Yamae is correct. Maybe the Old one was not in correctly?
Old 08-26-16 | 11:40 PM
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I am attaching a few more pictures that would show that the polarity of the capacitors match the signs on the board. Thanks.
Attached Thumbnails 1997 LS400 170K miles, Coolant Leaks, alternator not charging, ...-img_20160826_152901.jpg   1997 LS400 170K miles, Coolant Leaks, alternator not charging, ...-img_20160826_152844.jpg   1997 LS400 170K miles, Coolant Leaks, alternator not charging, ...-img_20160826_152822.jpg  
Old 08-29-16 | 02:26 AM
  #80  
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Originally Posted by ychen
I took the alternator out. I have a quick question. I would like to start the engine without the alternator to troubleshoot (meaning without the serpentine belt). Is it safe (without causing further damage to the engine) to run the engine without the belt for a few minutes?

Thanks.
I've had my belt jump off while driving my 95 LS and i drove all the way home like that. Yes it's fine to do it. You just won't have alternation (obviously) but also no power steering or AC
Old 08-29-16 | 07:59 AM
  #81  
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Are you sure you did a good soldering job? One can see lots of "cold joints". Ever heard of desoldering braid (to clean up excess solder) and flux?

Last edited by plexus914; 08-29-16 at 08:06 AM.
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