Braebyrn

1995 LS400.
I got this car a few weeks ago and have been fixing all of the problems. I am stuck on the following.....

The keyless entry remotes have new batteries. The door switches only work when the key is on. When you open the door, the footwell light and overhead lights do not come on. The door lights work though. Any ideas?

Today I changed the struts bar bushings and the water temperature sensor. That was fun. Yesterday it was the capacitors in the ECU. Last week was valve covers gasket and the Air Control Valve/ Idle Control Valve. Amazing power increase and no smoke!

Yamae

Those lights are not directly switched by the switch attached to pillars. In order to light up longer, those lights are controlled by semiconductors in the MPX network body computer. I worry that yours is not working properly. This problem often happens when trying to replace the dome light bulb short circuiting the current path.

Braebyrn

Thank you Yamae for your reply. Also thank you for the information that you and LSCowboyLS provided for the ECU repair. The car operates with such an improved difference.

I apologize for my negligence as I didn't check to see if the bulbs were burnt out and that the switch near the visor was switched to door. After I placed the switch in the correct position and installed two new bulbs, they illuminated and dimmed properly.

Now on to repairing the keyless entry remotes and the door switch that does not function properly. The door switch works when the key is turned to the "ON" position. All of the door locks work when the key is in the "ON" position and the door switch on the drivers or passenger side. The drivers side outside door key lock only unlocks the drivers door. From what I read, it should do more than that right?

I wonder if they are tied together with the keyless remote function?

Thank you
Braebyrn

Braebyrn

I cannot reprogram the keyless remotes to the car since the door lock switch will not open and close unless the LS400 key is in and in the "ON" position. The passenger door lock also will not operate unless the key is in the "On" position.......Any ideas? Where do I locate the shop manual for the wiring and relay diagrams?

Braebyrn

I have also discovered today that the power window control switch does not function for either mirror and the trunk release does not open the trunk unless the key is in the "ON" position. I checked all of the flat fuses under the dash and in the engine compartment. Ideas?

dicer

On a gen 1 it takes 2 turns of the driver door key to unlock all the doors. One thing that can cause that not to happen is the key switch contacts not making good contact.

Braebyrn

Dicer,
Is that only on the drivers side door? I tried it again tonight and no luck. If I can find a wiring diagram, that might help.

Since it was dark out, when I opened the door, the overhead light did not come on. The door courtesy lights came on though. The switch was in the correct "door" position. However it worked when the ignition switch is turned to the "On" position.

Someone is going to say, oh yeah, that's a relay, or that's this module........

Thanks Dicer.

Braebyrn

I opened the rear passenger doors and the overhead lights came on over each rear passenger door separately. Is there multiple light bulbs in the front overhead lighting? I know there is the map lights.

Braebyrn

Answered my own question. There is just the overhead bulb and the two map lights.

Yamae

There are five different computer units (1 MPX Network Body Computer and 4 MPX Network Door computers ) which are related to door switches. All of those computers communicate each other when switches are pressed. In accordance with the status of switches, computers activate doors lock/unlock, widows up/down or lights on/off. The MPX Network Body computer also handles the signal sent from the remote receiver. I have a wiring diagram for a Celsior written in Japanese. Since it contains many Japanese expressions and it will not be a help for non Japanese speaking people and I dare not upload it here.

What I worry about is that those computers are not communicating well. It is not very easy to distinguish which computer is not OK even if you have a wiring diagram.

According to my experience to help local shop owners as a volunteer, It is the often case that the "MPX Network Body Computer" is half dead. Most of failed one shows burnt semiconductors inside. Many of those are caused by the over current. I imagine that owners tried to replace the bulb and caused a short-circuit. Does your dome light work after a new bulb is installed?

Regarding to the ECU capacitor issue, congratulations on your success. It is our pleasure that your car runs better than before.

Braebyrn

The dome light bulb only works when the key is in the "ON" position and the door is opened. It's the same with the door lock switches, and the trunk release. The key must be in the "On" position to function.

I appreciate the offer of the wiring in Japanese, but you are right, I would not be able to understand the Japanese expressions. Where might I locate the MPX Network body computer on the vehicle? If I did replace that module from a donor vehicle, is it a plug and play, or does the car need to be reprogrammed to accept it? Are there other donor models that are the same? Or maybe, are the burnt semiconductors replaceable?

Yamae

In case of a JDM, it is located near the steering wheel shaft and also close to the fuse box under the dash. It looks like the photo which can be seen at the link below. To fix inside is almost impossible for average DIYers. It requires the circuit schematics, extra skills and equipments as well to find out which part is failed. It also requires to obtain the correct part. I do fix those but not every time. Parts are not easy to obtain and I need to use other equivalent ones. The quickest way would be to find it at auctions.
http://page4.auctions.yahoo.co.jp/jp/auction/d152053493

djamps

I'd start with the basics and test every fuse with a test light. Both under the hood and in the kick panel. And not just measuring continuity -- poke both ends of the fuses with a old school test light while the key is on and make sure you've got current on BOTH sides. I've seen fuses that looked normal and would pass a continuity test, but once current flows they turn into a resistor.

Braebyrn

Yamae, Thank you for the location. I may open it up to see if anything is burnt up. I don't have experience with very much on a circuit board. The ECU fix was about as adventurous as I have every been with one.

DJamps, I was using a volt meter testing each side of the fuse. I will use my test light instead tomorrow. Thanks for that bit of knowledge! How do you test the relays and larger square fuses?

Braebyrn

That was it. Thanks for the suggestion Djamps on using the test lamp! The test lamp worked only on one side. After replacing the faulty blade fuse on the SEC Horn, the doors now lock and unlock without the key in the "On" position along with the telescoping steering wheel! I didn't know that worked like that when you pull out the key! The key lock on the outside door handle also functions properly with the door locking and unlocking.

Yamae, on the dome light bulb, I took that out and tested it with the volt meter continuity tester and it did not show continuity. The metal end was barely hanging on and broke loose when I carefully removed it. Hopefully a new bulb will fix that issue also. Thank you for your suggestions also!

Sincerely,
Braebyrn