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

speedo and ecu issues

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Old 03-21-15, 07:39 PM
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baddluck87
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Default speedo and ecu issues

Hello everyone I have a 1996 ls400 that recently out of no where started giving me a host of issues.

check engine light is on.
Tried to scan codes and got a (no ecm link)

No speedometer
No odometer
No trip
No cruise control
No ect power function

Car feels sluggish in first drags on to 2nd and drives acceptable after that.
Reverse feels fine.

Tach works.

Got the capacitors replaced 2 days ago and the ecu checked out fine.

and ideas or help would be great. TIA.
Old 03-21-15, 09:00 PM
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RA40
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Welcome to Club Lexus. Did you verify by using the ripple test?
https://www.clublexus.com/forums/ls4...-by-yamae.html

It would be a hunt of throwing parts at it and that would be $$ going that way...need to get the ECU working to get some readable codes.
Old 03-21-15, 09:49 PM
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dicer
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How did the ecu check out fine? Did it get plugged into another car? Did it do all that stuff before the caps were changed? The no speedo etc sound like the cluster problem. No link, still have ecu problems. Did you have a link before the caps job? Sounds like someone might have ESD'ed the ecu.....
ESD Electrostatic Discharge.
Old 03-22-15, 12:24 AM
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Yamae
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Sounds like the speed signal is not properly processed by the ABS & TRC computer.
Does the ABS work?
Was the problem started all of a sudden?
Old 03-22-15, 05:53 AM
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baddluck87
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The ecu was sent in for repair and was verified as working by the shop that fixed it.

As far as the esd goes I don't think it's the case ....I drove the car to go wash clothes and all these issues all happened at once after I started the car to go home.

The ecu b fuse and obd2 fuses are not blown and are working.

I was reading about the ripple test but haven't tried it yet

I've never had issues with the car like this before except for the random flickering airbag light.

The check engine light was always due to a O2 sensor and would clear up from time to time but that was it.

I noticed that my progress snapshot just stopped working one day and the CEL came on and hasn't been right ever since I tried to pull those codes which originally led me to think it was the ecu caps.

Replaced those and cleaned up the board and it's still the same.

As far as the ABS goes there aren't any lights or codes for it popping up so I would assume it's functional?

Also ect power does nothing once I turn it on ...the light doesn't even come on in the cluster

Last edited by baddluck87; 03-22-15 at 05:57 AM. Reason: additional post text.
Old 03-22-15, 10:53 AM
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RA40
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If you pulled the O2 codes, that is a first place to start. Get those done because those will contribute to a rich running condition and that may kill the cats depending how long it is driven.

My next thought is to pull the ECU to check the soldering and caps. If you post a clear pic of the caps then Yamae can have a better idea of the caps and board condition. Damage to the PCB from the fluid can toast it so that still remains suspect.
Old 03-22-15, 01:27 PM
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dicer
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I'd start looking for an ecu out of another known good running car. Maybe one of the new caps popped already, maybe not the correct size or ?

I forget if it was Lscowboy or ? that said all ecu's sent to shops are not repaired with the right caps, so yes suspect it.
Old 03-22-15, 02:24 PM
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RA40
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Yes, that is the discussion about low ESR caps being used.
Old 03-22-15, 04:58 PM
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It was the ecu ...swapped it out for another one and everything works like it should
Old 03-22-15, 05:18 PM
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Yamae
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So you are showing another bad example of an incorrectly repaired ECU using may be incorrect capacitors.
You'd better fix the ECU using right capacitors listed at the FAQ page. Even a non-engineer girl is replacing capacitors at below.
Old 03-22-15, 05:55 PM
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Well I'm not solder savvy can it still be repaired ....I would hope so? I'd rather send it to someone that knows what their doing. anyone in the forum that you guys know of that can do it.


Lesson learned
Old 03-22-15, 08:24 PM
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Yamae
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It's almost time or era when a DIYer needs to be able to change capacitors as you do spark plugs changes.
Modern cars use many electronics parts and among those, electrolytic capacitors are the most frequent parts that need to be changed. Watch the video and see how that girl does. It's easier than to replace spark plugs. You don't need strong muscles.
Old 03-22-15, 08:51 PM
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Yamae I've tried this work before on honda ecus failed miserably.
It's just one of those things that I'm not good at. I'll watch the video and make my conclusion based on that. It would be nice to have a ecu bench tester.
Old 03-23-15, 08:27 AM
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After further investigation and the repair shop did the correct repair and used the correct capacitors the ecu was damaged by the progressive snapshot device....the ecu was working until after that point..and apparently I'm not the only one ...so word of warning to the folks that have them as this ecu cannot be repaired ...time to source another one and get those caps replaced
Old 03-23-15, 10:04 AM
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Unless the car is commercially owned or a teen is driving it, tapping one of these black boxes into the system seems I don't know what type of insurance break would result. Glad you found this out.


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