2002 LX 470 crank, no start, no check engine light, no communications to the ECU (1 Viewer)

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envyseapets

envyseapets

Joined
Jul 23, 2020
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Hi,

I've read a bunch of similar threads, but can't quite figure out what's going on... My LX 470 cranks, but doesn't start. I have no check engine light and can't connect to the ECU over OBD II.

I thought that the ECU may be bad, mailed it to a service, they said it's not fixable and sent me a remanufactured unit, I replaced the ECU and exactly the same problem.

I do see the immobilizer light blinking when I turn the key on.

I see some threads that say it maybe EFI fuse or the fuse box itself or the MAF or the immobilizer, not sure how to proceed. Should I see a check engine light go on when I turn the key to the on position but haven't started the car yet? Should immobilizer light go off?
 
Red light should go off. @medtro has your solution.

forum.ih8mud.com

My immobilizer fix

I got the famous crank but not start immobilizer problem. I replaced the 20A EFI fuse with a 30A fuse and it started right away. However, it was a temporary fix. I had the same problem again 4 days later. This is what I did to get the engine started. It has been working with no problem for...
forum.ih8mud.com forum.ih8mud.com
 
envyseapets said:
Hi,

I've read a bunch of similar threads, but can't quite figure out what's going on... My LX 470 cranks, but doesn't start. I have no check engine light and can't connect to the ECU over OBD II.

I thought that the ECU may be bad, mailed it to a service, they said it's not fixable and sent me a remanufactured unit, I replaced the ECU and exactly the same problem.

I do see the immobilizer light blinking when I turn the key on.

I see some threads that say it maybe EFI fuse or the fuse box itself or the MAF or the immobilizer, not sure how to proceed. Should I see a check engine light go on when I turn the key to the on position but haven't started the car yet? Should immobilizer light go off?
Click to expand...
I just responded to your message. I agree with @BullElk you should probably start in the fuze box under the hood.
 
@Mauser thanks for the follow-up to the direct message, you suggest that there may no be power to the ECU and I should check the connections on the 20A EFI fuse and the connection. I assume I should also check the EFI relay?

If there is power to the ECU, I would expect to see a check engine light?
 
envyseapets said:
@Mauser thanks for the follow-up to the direct message, you suggest that there may no be power to the ECU and I should check the connections on the 20A EFI fuse and the connection. I assume I should also check the EFI relay?

If there is power to the ECU, I would expect to see a check engine light?
Click to expand...
Yeah. You won't have the engine light and the ecu won't recognize your key.

Once you get the check engine light to come on you should be able to handshake your new ecu to the immo ecu.
 
Thank you, @Mauser -- I checked EFI and ECU-B fuses, they were fine, but I noticed one of the metal latches for the EFI fuse is ... missing?! What's my next step? Take out the fuse box and try to fix it? Replace the fuse box? @medtro's bypass kit?

IMG_1246.jpeg
 
@medtro Bypass kit. A new box is about $700 last I heard and I don't think the issue was resolved in the new boxes either.
 
Also, when you say handshake, is that the short pins 4 and 13 and wait 30 minutes? I did do that already.
 
envyseapets said:
Thank you, @Mauser -- I checked EFI and ECU-B fuses, they were fine, but I noticed one of the metal latches for the EFI fuse is ... missing?! What's my next step? Take out the fuse box and try to fix it? Replace the fuse box? @medtro's bypass kit?

View attachment 3652584
Click to expand...
The bypass kit seems to be the easiest fix. If mine were to do that I would probably solder in an inline fuze holder.

A lot of folks here refer to the bypass @medtro builds as a band-aid and say that you should replace the fuze box. As far as I know replacing the fuze box is just a temp fix because the melting terminal problem was never really fixed.
 
envyseapets said:
Also, when you say handshake, is that the short pins 4 and 13 and wait 30 minutes? I did do that already.
Click to expand...
Yes, but when you did it your ecu wasn't being powered up properly.
 
Side question, what are the odds that my original ECU was totally fine and the ECU repair vendor is not being honest about me needed a new ECU. I had asked them to mail the original one back with the replacement, and they did not.
 
envyseapets said:
Side question, what are the odds that my original ECU was totally fine and the ECU repair vendor is not being honest about me needed a new ECU. I had asked them to mail the original one back with the replacement, and they did not.
Click to expand...
The odds that your original ecu was fine are pretty good. Very, very rarely do I come across a bad ecu. 99% of the time if the ecu is bad it is caused by water getting unto it.
 
@Mauser How easy or difficult would it be to take out the fuse box and solder on a new fuse holder? I am pretty handy with soldering, and may even have some (larger) fuse holders lying around, I am less handy with taking off vacuum hoses (looks like I need to remove a few things to get access) and other car components lol. Do you have any pictures of underside of the fuse box handy perhaps?
 
envyseapets said:
@Mauser How easy or difficult would it be to take out the fuse box and solder on a new fuse holder? I am pretty handy with soldering, and may even have some (larger) fuse holders lying around, I am less handy with taking off vacuum hoses (looks like I need to remove a few things to get access) and other car components lol. Do you have any pictures of underside of the fuse box handy perhaps?
Click to expand...
Not easy to R&R the box. My thought is to cut it out from the top.

I do not have any pictures.
 
Is the EFI fuse only used to power the relay? Could I just run a new fused wire from battery positive to the EFI relay directly?

It looks like the EFI fuse output also goes to the BATT terminal on the ECU? What is that used for.. power or just an indicator?

@Mauser
IMG_1248.jpeg
 
Last edited:
envyseapets said:
Is the EFI fuse only used to power the relay? Could I just run a new fused wire from battery positive to the EFI relay directly?

It looks like the EFI fuse output also goes to the BATT terminal on the ECU? What is that used for.. power or just an indicator?

@Mauser
View attachment 3652654
Click to expand...
If you check out the link @BullElk posted the first post should tell you what you need to know.
 
I was actually able to get the EFI fuse to work by inserting a metal shimmy into the slot so the contacts are able to be made! Now I am at the immobilizer key unrecognized problem, I did the 30 mins pin 4 and 13 short, I can connect to the immobilizer via TechStream, but I don't seem to have the Utility function to program the key
 
envyseapets said:
I was actually able to get the EFI fuse to work by inserting a metal shimmy into the slot so the contacts are able to be made! Now I am at the immobilizer key unrecognized problem, I did the 30 mins pin 4 and 13 short, I can connect to the immobilizer via TechStream, but I don't seem to have the Utility function to program the key
Click to expand...
What version of Techstream are you using? What is the part number of your ecu?
 
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