ECM Eater
Thread Starter
Driver School Candidate
Joined: Feb 2012
Posts: 16
Likes: 0
From: Maryland
ECM Eater
It seems my 1994 LS400 is an ECM eater. It has eaten five. I need help in troubleshooting. The vehicle is in an independent shop and the mechanics are scratching their heads. Here are the symptoms:
The CEL light is off. The air bag light is on. The car will run well with a new ECM for a while and then will stall and in three days drain the battery. The ECM codes cannot be read consistently on a Snap-On 2500 or a Motus computer. In both cases the data stream flashes. As the ECM fails it has a hard time starting, transmission will not shift and rough or stalling engine above 2000 RPM. The mass air flow sensor and coolant temperature sensor has been replaced. I have a first world problem – I’m down to three cars! What should I do?
The CEL light is off. The air bag light is on. The car will run well with a new ECM for a while and then will stall and in three days drain the battery. The ECM codes cannot be read consistently on a Snap-On 2500 or a Motus computer. In both cases the data stream flashes. As the ECM fails it has a hard time starting, transmission will not shift and rough or stalling engine above 2000 RPM. The mass air flow sensor and coolant temperature sensor has been replaced. I have a first world problem – I’m down to three cars! What should I do?
Thread Starter
Driver School Candidate
Joined: Feb 2012
Posts: 16
Likes: 0
From: Maryland
Probably it would be sensible to salvage the car. However, the car does have some sentimental value; I inherited it from my dad last year. Is there a systematic way of tracing down a short?
Rookie
Joined: Nov 2011
Posts: 98
Likes: 5
From: VA
The first thing that comes to mind is a voltage stability issue. You may have an alternator with bad diode(s), voltage regulator, or a battery with a shorted cell. Have the battery load tested. If it checks out good, temporarily disconnect the alternator and run it on the battery only. Recharge the battery as needed with a battery charger. See if the problem goes away.
Rookie
Joined: Sep 2011
Posts: 97
Likes: 0
From: NYC
Trending Topics
ClubLexus Stories
Celebrating Lexus & Toyota from Around the Globe
8 Tips for Improving Your Hybrid or Plug-in Hybrid's Efficiency!
Michael S. Palmer
10 Best Lexus Models No One Remembers
Joe Kucinski
TRD Off-Road Premium: Best 2026 4Runner, Except This One Thing
Michael S. Palmer
Top 10 Lexus & Toyotas to Drive Before You Die!
Joe Kucinski
Top 10 Lexus/Toyotas With The LEAST 5-Year Depreciation
Joe Kucinski
Lexus LC500 Convertible Auction: A Preview of Rising Values?
Brett Foote
GX 550 vs TX 550: Best 3-Row Luxury Lexus Family Hauler
Michael S. Palmer
9 Best Lexus Models You Can Buy for Half Price (And 1 You Shouldn't!)
Joe Kucinski
2026 Lexus NX Buyer's Guide: Models, Features, Prices & More!
Brett Foote
first and foremost..do not take the vehicle back,find another shop that specializes in electrical
secondly...ask them how they concluded ur ecm was bad
thirdly....once the second ecm was determined to be bad..ask if they tried to figure out the cause and effect issue..meaning the ecm was the effect of another cause..so what is that cause?
fourth..ask for ur money back on any diagnosis and repairs, u wont get any money back for parts.
fifth..(if they refuse to give u any money)let them know if ur not reimbursed u will be calling BAR and will also give negative reviews on yelp and word of mouth can be just as detrimental.
FIVE ECM'S! are u kidding me..what a flippin joke!
secondly...ask them how they concluded ur ecm was bad
thirdly....once the second ecm was determined to be bad..ask if they tried to figure out the cause and effect issue..meaning the ecm was the effect of another cause..so what is that cause?
fourth..ask for ur money back on any diagnosis and repairs, u wont get any money back for parts.
fifth..(if they refuse to give u any money)let them know if ur not reimbursed u will be calling BAR and will also give negative reviews on yelp and word of mouth can be just as detrimental.
FIVE ECM'S! are u kidding me..what a flippin joke!
Thread Starter
Driver School Candidate
Joined: Feb 2012
Posts: 16
Likes: 0
From: Maryland
first and foremost..do not take the vehicle back,find another shop that specializes in electrical
secondly...ask them how they concluded ur ecm was bad
thirdly....once the second ecm was determined to be bad..ask if they tried to figure out the cause and effect issue..meaning the ecm was the effect of another cause..so what is that cause?
fourth..ask for ur money back on any diagnosis and repairs, u wont get any money back for parts.
fifth..(if they refuse to give u any money)let them know if ur not reimbursed u will be calling BAR and will also give negative reviews on yelp and word of mouth can be just as detrimental.
FIVE ECM'S! are u kidding me..what a flippin joke!
secondly...ask them how they concluded ur ecm was bad
thirdly....once the second ecm was determined to be bad..ask if they tried to figure out the cause and effect issue..meaning the ecm was the effect of another cause..so what is that cause?
fourth..ask for ur money back on any diagnosis and repairs, u wont get any money back for parts.
fifth..(if they refuse to give u any money)let them know if ur not reimbursed u will be calling BAR and will also give negative reviews on yelp and word of mouth can be just as detrimental.
FIVE ECM'S! are u kidding me..what a flippin joke!
Thread Starter
Driver School Candidate
Joined: Feb 2012
Posts: 16
Likes: 0
From: Maryland
Let me add that when the car was rear-ended, it was pushed into the car in front of it, damaging back and front. The insurance company repaired it and everything worked fine for a couple of years after that. I like your suggestion and will pass it on. Thanks.
Last edited by tbradford; Feb 26, 2012 at 09:57 AM. Reason: spelling
Thread Starter
Driver School Candidate
Joined: Feb 2012
Posts: 16
Likes: 0
From: Maryland
Does anyone understand circuitry enough to suggest what circuit could have caused the damage (discolored board) at the capacitor?
Wow...do the other ECM's fail at that same location?
Without a schematic for the tracings, that will be a pain to dig through. What is the underside of that like? Something is getting quite hot. That cap didn't burst unless it leaked from the bottom pin and caps can take some heat in their usual operation. Checking the pinouts of the connector tot the ECM for their specs is about all I could suggest.
Run that ECM by the parts or technician at Lexus or Toyota and see if they have any idea what may be happening.
GL
Without a schematic for the tracings, that will be a pain to dig through. What is the underside of that like? Something is getting quite hot. That cap didn't burst unless it leaked from the bottom pin and caps can take some heat in their usual operation. Checking the pinouts of the connector tot the ECM for their specs is about all I could suggest.
Run that ECM by the parts or technician at Lexus or Toyota and see if they have any idea what may be happening.
GL
Thread Starter
Driver School Candidate
Joined: Feb 2012
Posts: 16
Likes: 0
From: Maryland
Wow...do the other ECM's fail at that same location?
Without a schematic for the tracings, that will be a pain to dig through. What is the underside of that like? Something is getting quite hot. That cap didn't burst unless it leaked from the bottom pin and caps can take some heat in their usual operation. Checking the pinouts of the connector tot the ECM for their specs is about all I could suggest.
Run that ECM by the parts or technician at Lexus or Toyota and see if they have any idea what may be happening.
GL
Without a schematic for the tracings, that will be a pain to dig through. What is the underside of that like? Something is getting quite hot. That cap didn't burst unless it leaked from the bottom pin and caps can take some heat in their usual operation. Checking the pinouts of the connector tot the ECM for their specs is about all I could suggest.
Run that ECM by the parts or technician at Lexus or Toyota and see if they have any idea what may be happening.
GL
Not sure where I can find the pinouts and ECM specs - need to research.