avhart

Hi guys, my 93 Celsior is down at the moment waiting on a rebuilt ECU from the US. While waiting I notice the rear air sus tends to go down due to a small leak on the right shock. Is there a way to run the air compressor manually with maybe a jumper somewhere since the engine cannot start?

I did a lot of searching to see if there was but couldn't find anything like that. Any help would be appreciated. I don't want to muck it up.

Thanks

timmy0tool

iTrader: (7)

why not just turn the key to the ON position, even though the engine is off and cannot start? i would think that should run the compressor if all the air suspension components are in working order. of course this would drain the battery so be weary of the voltage draw.

hot wiring the compressor is another solution but that is more intrusive.

avhart

Hey Timmy. was hoping to hear form you. The key thing doesn't work on my car. The engine has to be started for the compressor to come on.

So how do you hot wire it?

timmy0tool

iTrader: (7)

hmm i suspect the ECU needs to know the engine is on in order to run the compressor to keep the alternator charging is my guess.

i'm not familiar with factory air suspension, but i know yamae is - at least he has access to lots of schematics to show how the compressor is wired. hope he chimes in!

avhart

Fair enough. Thanks a lot there Timmy.

Yamae are you there?.... We're waiting to hear from you lol

timmy0tool

iTrader: (7)

found a thread that yamae posted, see post #5:
https://www.clublexus.com/forums/ls-...sion-leak.html

step 2B shows how to "hot-wire" the compressor. might differ on a RHD celsior but should be similar.

avhart

Timmy your a gem. I really looked myself for that info but just couldn't find it. Now I notice that this is for a 2000 LS and 93 Celsior might be somewhat different but I have a lot to work with here thanks to you finding Yamae's post. I will see how it relates to my car and provide an update when I have information.

Can't thank you enough.
Anthony

Yamae

Attached is a part of the circuit diagram for a 94 Celsior's air suspension system and is not for a 93 but things must not be different too much. The motor (near the lower left corner) is getting the power via 120A alternator fuse, 40A air suspension fuse and the height control relay which is driven by the air suspension control computer. The motor can be driven manually simply bypassing the relay. Sorry that I don't have a circuit diagram for a Gen 1 and I only can provide you this. The lower side of the motor is grounded via the current sensing registor, I must add. I hope this might help you some.

avhart

Thank you once again for your input Yamae. That is very important additional information. Together with what Timmy has sent me earlier I should be able to figure everything out. I will post my results when I have them.

Happy Christmas and Holidays to everyone.

Anthony

timmy0tool

iTrader: (7)

no prob sir. funny the instructions to hot wire are for a 2000 but the stock picture of the vehicle in the diagrams is a 1st gen haha! glad to help in any way.

cheers!

avhart

Thank you Timmy, All good guys in this forum I think..

avhart

Hey Yamae, my car has two height control relays, front and back. Will bypassing either relay start up the compressor? Is there, by chance, a way to run the compressor by a jumper in the TDCL?

deanshark

I remember on my old 93 LS400 which had factory air suspension there was a way to jump the compressor but I can't remember how. Something in the trunk I think. That was 12 years ago. Sorry, I know that doesn't help ya but I got a question for ya instead. Why are you trying to jump it in the first place? Why don't you just wait for your ECU to come back then you can start the car and it'll pump back up. Ya can't drive it now without the ECU anyway. How long til you get your ECU back? Plus, I don't think it's good to have the battery hooked up without the ECU in. Just my thought.

avhart

Hey dean, nice to hear from you. The reason is that I have a small leak on one of my rear shocks and the car sinks unevenly in the back and just does not look attractive sitting there in my garage. Not that big a deal I know, but still...

The connector to run the pump is really in the trunk but to get at it would mean removing most of the trim covers which I would like to get away from, if I could help it. So I'm looking for an alternate way. Again I believe you are quite right about running the air pump without the ECU connected but I actually have another ECU hooked up but its not all that good either and is no longer starting the car. This is a new problem because it used to work pretty good until it just quit.

Now I'm guessing it is the old ECU causing the issue because I'm not getting any spark although the coils are receiving power when I turn the ignition on. If you have any suggestions about this my other very recent no-start problem I'd love to hear your thoughts. I believe the CPS can cause it but I don't think its that because it never showed any symptoms before.

Anthony
PS the ECU's not showing any codes...

deanshark

Yea everything works, until it doesn't. I've had a couple crank sensors go bad on other cars, (GM) never on my LS400s, but ya never know. The ECU not reading any codes, even the "all is good" code means that ECU is not good. One of my ECUs was working perfect til one night I shut it off and the next morning I went out and it wouldn't start. I opened that ECU up and found one of the caps was burnt right off and just bouncing around inside. So, that can go out at any time also.