UTsleeper

Small back story. Bought this 1992 LS400 (build 8/1991) a couple days ago. PO had it running and it was registered. He replaced the power steering pump he said, than the car quit starting after that. He than got so frustrated after not being able to figure out the issue, he threw the ECU at the windshield. His knowledge seemed minimal as he is only 17 and seemed to do some weird things(such as remove the ECU to troubleshoot lol).

So, here we are. I bought the car off him for 200. It has some body damage from other PO's and I have mostly bought it as a donor for another car. But till I am at a point that I want to remove the motor, I would like to get the engine running and have it be movable and also in a state that I can fix other engine related issues that may be present.

Issue: No CEL when key is in on position. All other lights appear to light up as expected. Car does not start, just cranks.

What has been:
PO bough used ECU(appeared to be a non trac version)
I bought a used ECU that was a trac version, which then removed the trac light on the dash. Out of a 1990. ECU conditions are unknown.
I swapped the CEL light bulb with a known working one and still no CEL, while the bulb that was previously in the CEL spot was working.
Checked the EFI fuse under the hood and replaced. Also checked fuses under the dash that had names that seemed like it may have been related.
Swapped out relays under the hood to try and rule things out.

That is what I can remember trying. Engine appears to turn over well.

Now, I am prepared to start removing the PS pump to try and see if the PO messed something up in that area, but I figure I would ask for assistance first.

Are there any things I can do to check the light, functionality, etc? Any ideas on how I should approach this next?

RA40

iTrader: (6)

Welcome to Club Lexus. Some reference info:
https://www.clublexus.com/forums/ls-...a-yamae-2.html

UTsleeper

So, I am guessing the capacitors can cause the ECU not to talk at all. I have seen posts talking about it, but it seemed most people could still get their car to start. I will crack my ECU open just to see if there is sign of leakage. I know thats not a definite indicator of bad caps, but makes it easy to spot lol.

Also, the "new" ECU is a 50020. I will check the ecu that the PO put in.

UTsleeper

So, I ordered an ECU that is the right part number for the car (89661-50042). Still no check engine light with the key on. With that I get no spark and I don't believe I hear the fuel pump kick on when the key is in the on position.

Any suggestions on what to check? Is there a way to validate the integrity of the CEL light/wiring?

Moarpower

No spark and no fuel pump? The car is well insulated so hearing the fuel pump can be difficult.

Ensure there is no spark by spraying a little starter aerosol in the throttle body.

As for the fuel pump, it could be dead or it could be a bad circuit opening relay which is mounted near the ecu

Moarpower

Sounds like the previous owner has messed something up. So do a meticulous check of all ignition and timing leads and sensors as well as fuses and other things he may have screwed with while troubleshooting

UTsleeper

So, small update.

Still no check engine light.

But as suggested, I tried to start it with starting fluid. And the damn thing would idle with starting fluid. So, apparently I was just unable to see the spark on the spark plug wires when cranking it. So, I am going to replace the FP and see if she will start, but would like to fix the CEL so that I can pull codes.

Also, a little off topic, but are you suppose to be able to put the car in gear when not running? I can't shift it out of park without pushing the manual override button.

UTsleeper

And thank you for reminding me to atleast try this. Definitely changed the direction I thought I was going with this.

UTsleeper

Small update.

Replaced the fuel pump and the pump appears to still not come on. I have the back seat out to try and hear the pump.

I tried jumping Fp with B+ under the hood with no signs of the pump coming on.

I left the key in the on position and pulled the FP relay on the passenger side, thinking I would hear the relay click when plugging back in. It did not click.

So, looking for other suggestions on what to try to resolve the FP side of this issue. If I can get the car started than I may not worry too much about the check engine light, but would like to resolve that.

Thanks for any suggestions.

Htony

Won't Tech stream help?

UTsleeper

I am not familiar with this. Is this something that works with pre OBD 2 cars?

Yamae

Did you check the circuit opening relay?
When it's contact is open, the fuel pump is disabled.

Htony

I think older car has different connector for OBD port which nees a cable adapter. If really old it may not even have OBD port.
Have to know first hand OBD port works which would indicate the logic is working. Other wise CEL will never come on. Oh,
another thing when you turn the ignition on all the lights on the dash come on? I never had a car more than 6 years old.

UTsleeper

Where is this circuit/relay? I am not familiar with this. And how do you check it?

Michael88

Broken or cracked key or key fob will not allow the transponder to deactivate the security. Resulting in a security caused no starting engine. Is your key whole or damage?