how to check your ECU without removing it from car - by Yamae - Page 3 - ClubLexus - Lexus Forum Discussion

Go Back  ClubLexus - Lexus Forum Discussion > Lexus Model Forums > LS Models > LS - 1st and 2nd Gen (1990-2000)
how to check your ECU without removing it from car - by Yamae >

how to check your ECU without removing it from car - by Yamae

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

how to check your ECU without removing it from car - by Yamae

Old 01-28-15, 03:38 PM
  #31  
Caseyjones
Rookie
 
Join Date: Jul 2014
Location: South Dakota
Posts: 97
Thanks: 0
Thanked 0 Times in 0 Posts
Default

I finally got my test capacitor. I called them and tried to order this one as was in this post.
http://www.digikey.com/product-detai...4544-ND/111793 but they were out of it and said its end of life but that this one superseded it. It says film capacitor but does look different.

Here is what I got.
http://www.digikey.com/product-detai...1112-ND/592690
Is this ok to use in its place? BTW it does look just like the picture.

I plan to do ECU capacitors but would really like to put it off until Fall if I can, right now I'm running down a couple other minor issues and want to make sure the ECU has nothing to do with any other symptoms.

Thanks.
Caseyjones is offline  
Old 05-09-15, 09:00 PM
  #32  
dicer
Lexus Champion
 
Join Date: Jul 2010
Location: ca
Posts: 4,478
Thanked 69 Times in 65 Posts
Default

Okay finally was going to do this test, this is for a 90. Well I think the OP1 in the connector is marked as OPt, and that hole is empty. So what are the test points on this one? I thought I remember something about the ect, but that is not a fun deal to get to. So what is a nice easy alternative? Is the main goal to look for ripple on a nonpulse sensor? Since the ect would be more of a nice slow analog signal is that the reason for using it?
dicer is offline  
Old 05-10-15, 08:44 PM
  #33  
Yamae
Lexus Champion
 
Join Date: Aug 2011
Location: Japan
Posts: 2,141
Thanked 143 Times in 113 Posts
Default

Originally Posted by dicer View Post
Okay finally was going to do this test, this is for a 90. Well I think the OP1 in the connector is marked as OPt, and that hole is empty. So what are the test points on this one? I thought I remember something about the ect, but that is not a fun deal to get to. So what is a nice easy alternative? Is the main goal to look for ripple on a nonpulse sensor? Since the ect would be more of a nice slow analog signal is that the reason for using it?
You are quite right, dicer. The ECT is one of the easiest choices although it's not as easy as to check at the OP1. Other than the ECT, there are some more but none of them are easy to access. If you find any, please let us know.

A quarter century old those QAS capacitors are already too old to survive and I always suggest people to replace those if you can as a preventive measure. I'm quite comfortable handling electronics boards and may be my standard is a bit different from others but a girl below is still doing a similar job all by her self. Sorry to introduce this again to boys who are not comfortable handling soldering irons as her. I feel very sorry for them to survive in the 21st Century when and where printed circuits boards are at everywhere in your house and around. They could enjoy their life more If they were comfortable doing something like this.

Last edited by Yamae; 05-10-15 at 08:49 PM.
Yamae is offline  
Old 05-10-15, 09:58 PM
  #34  
dicer
Lexus Champion
 
Join Date: Jul 2010
Location: ca
Posts: 4,478
Thanked 69 Times in 65 Posts
Default

I worked at a place that did electronics assembly, and we had an older woman that was really good at doing surface mount stuff with a soldering iron, the assembly is easy its the removing the components that are already on the board that can be fun.
dicer is offline  
Old 07-22-15, 12:38 PM
  #35  
SonomaSC4
Driver School Candidate
 
Join Date: Jul 2015
Location: CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default correct meter

Hello, using a Fluke #27 mulitmeter to do this test, it only reads to 40 Khz. will this meter provide an accurate reading or should i find another?
SonomaSC4 is offline  
Old 07-22-15, 06:14 PM
  #36  
Yamae
Lexus Champion
 
Join Date: Aug 2011
Location: Japan
Posts: 2,141
Thanked 143 Times in 113 Posts
Default

Originally Posted by SonomaSC4 View Post
Hello, using a Fluke #27 mulitmeter to do this test, it only reads to 40 Khz. will this meter provide an accurate reading or should i find another?
40KHz is not high enough and the readout voltage would be smaller but I'd say better than nothing. Try using it and inform me the result.

The ripple or the switching noise contains the RF energy and even pulses higher than 100MHz can be observed by a spectrum analyser. But the major energy exists up to 300KHz or less. That is why the meter up to 300KHz can be used with some compensations. 40KHz is much less but still the major energy tends to exist at the lower side of the the spectrum and the compensation would work. My rough estimation in accordance with my past experience, you can read 2/3rd of the whole ripple energy even with 40KHz meter. So roughly speaking, 30mV or a bit less would be the limit in your case.

See the page below and you can see the difference depending on meters.
https://www.clublexus.com/forums/ls-...-symptoms.html

Last edited by Yamae; 07-22-15 at 06:19 PM.
Yamae is offline  
Old 07-22-15, 08:38 PM
  #37  
SonomaSC4
Driver School Candidate
 
Join Date: Jul 2015
Location: CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Yamae, we got a reading of 17.2 just after starting a cold motor. its a 1995 SC4, after the motor warmed it dropped to 16.8.
SonomaSC4 is offline  
Old 07-22-15, 08:51 PM
  #38  
SonomaSC4
Driver School Candidate
 
Join Date: Jul 2015
Location: CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default

This is the tale of my troubles, about a month ago the radiator let go while my wifey was parked. She shut the motor off right away. towed to my mech, replaced the rad, when i picked it up the air bag light was on. my mech said that the key got left on by the tow truck drivers and the battery went dead. After he charged the battery the light came on and has been on ever since. I drove it for a day or so and it started to just die at slow speeds, it would either start right back up and run fine like nothing happened, it did that a couple of times until it died and then it would just start back up and die right away. Does the air bag light give any clues? only codes its giving are "22" which my mech says is a hard fault in the airbag circuit.
Thanks
I
SonomaSC4 is offline  
Old 07-22-15, 08:54 PM
  #39  
SonomaSC4
Driver School Candidate
 
Join Date: Jul 2015
Location: CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Of course the mech got it to die only once and it wants to run fine now
SonomaSC4 is offline  
Old 07-23-15, 12:51 AM
  #40  
Yamae
Lexus Champion
 
Join Date: Aug 2011
Location: Japan
Posts: 2,141
Thanked 143 Times in 113 Posts
Default

Originally Posted by SonomaSC4 View Post
Yamae, we got a reading of 17.2 just after starting a cold motor. its a 1995 SC4, after the motor warmed it dropped to 16.8.

This is the tale of my troubles, about a month ago the radiator let go while my wifey was parked. She shut the motor off right away. towed to my mech, replaced the rad, when i picked it up the air bag light was on. my mech said that the key got left on by the tow truck drivers and the battery went dead. After he charged the battery the light came on and has been on ever since. I drove it for a day or so and it started to just die at slow speeds, it would either start right back up and run fine like nothing happened, it did that a couple of times until it died and then it would just start back up and die right away. Does the air bag light give any clues? only codes its giving are "22" which my mech says is a hard fault in the airbag circuit.
Thanks
Judging from the readout voltage 17.2/16.8mV and others, I don't think your ECU causes any serious problems.

Regarding the air bag light, I suspect that your mech might did something wrong to the air bag sensor/connector/harness when he did the radiator job or the overflowed cooling liquid damaged on of those.
Yamae is offline  
Old 08-11-15, 07:08 PM
  #41  
bwonder381
Driver School Candidate
 
Join Date: Jun 2015
Location: TN
Posts: 17
Thanks: 0
Thanked 0 Times in 0 Posts
Default

I have 1995 LS400 and I'm having the problem. I took it to autozone and they did a diagnostic and it came out with the ecm problem. I was able to drive it, but one morning it just would not start. It just click. My power comes on, radio, lights, etc... I've reset the ecu and charged the battery and it stills just clicks when I turn the key.
bwonder381 is offline  
Old 08-11-15, 07:28 PM
  #42  
cobalt91
Lead Lap
 
Join Date: May 2012
Location: MI
Posts: 586
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Originally Posted by bwonder381 View Post
I have 1995 LS400 and I'm having the problem. I took it to autozone and they did a diagnostic and it came out with the ecm problem. I was able to drive it, but one morning it just would not start. It just click. My power comes on, radio, lights, etc... I've reset the ecu and charged the battery and it stills just clicks when I turn the key.
Sounds like you need to check the fuses first. Then have the starter checked. I don't think the ecu would have much to do with this issue.
cobalt91 is offline  
Old 08-11-15, 08:01 PM
  #43  
bwonder381
Driver School Candidate
 
Join Date: Jun 2015
Location: TN
Posts: 17
Thanks: 0
Thanked 0 Times in 0 Posts
Default

I let someone place a diagnostic device on my car and check it out and the next day it would not start. He looked at all the fuses and looked under the car.
bwonder381 is offline  
Old 08-24-15, 01:40 PM
  #44  
russell94
Driver School Candidate
 
Join Date: Aug 2015
Location: AZ
Posts: 16
Thanks: 0
Thanked 0 Times in 0 Posts
Default

i could use one. my ls 400 will start but wont move at all.
russell94 is offline  
Old 08-24-15, 07:36 PM
  #45  
bwonder381
Driver School Candidate
 
Join Date: Jun 2015
Location: TN
Posts: 17
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Originally Posted by cobalt91 View Post
Sounds like you need to check the fuses first. Then have the starter checked. I don't think the ecu would have much to do with this issue.
Found out it was me. I was using my hand to tighten up the nut on the battery post. I decided one morning to find the socket for it and tighten it up. When I did, the car crank right up and been running every since. Even the engine error light has went out.
bwonder381 is offline  

Thread Tools
Search this Thread
Quick Reply: how to check your ECU without removing it from car - by Yamae


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: