Greetings, so I did the ECU capacitor replacement and once I put it back in, after giving it a min to charge, the car started beautifully. It only seemed to fix my high idling.
Also noticed the diagrams showing the ECU location on my lexus was NOT in the vertical orientation but in the horizontal orientation under the passenger glove compartment. Weird.
I am still seeing following issues:
- tachometer not working (console swap/rebuild?) Slammed on the dash and no movement.
- odometer busted, probably need to contact Tatin to get the gear purchased.
- temp running pretty high about one tick under redline. Probable due to the next issue...
- both radiator fans not moving, when car starts up, they both spin and then slow to a standstill even after driving a few hours.

I've checked the relays under the drivers headlight, even went as far as swapping the main square relay and one of the round RADFAN relays, no change.
Any suggestions would be welcome. Thanks in advance.

 

Instrument cluster is potentially a separate issue to the ECU of the car. It can fail independently and require it's own rebuild.

For your cooling issue - radiator has two fans. One small auxiliary electric fan that really is for the air conditioning. The primary fan is driven by the hydraulic clutch. It's possible that yours is worn out and free-wheeling. This being said, they typically fail in a manner in which they are stuck "on" all the time. It sounds like a truck, but at least your car won't overheat. It's rarer for them to fail "open" like this. Do the standard tests for this fan to make sure it's functioning correctly. Even when the car is fully cold and this clutch is fully open, it should still be rotating the fan at least somewhat. The hotter the car gets, the more it should "bite" and the faster the fan spins. If this fan checks out, idk, investigate the rest of the cooling system. Is the coolant fluid healthy? Water pump? Radiator clogged because someone put the wrong "universal" fluid in there, it mixed, in there and gummed up the internals?

 

Thanks, I've noticed the AC motor does spin when AC is clicked on, but the radiator fans don't spin. They only spin when the engine starts or when I pop the relay off and back on physically.

I'll do a coolant flush and see if anything can be found. It was my dad's car, he was the one and only owner and he had it serviced, timing belt chaged, etc, around at 100K, which was around 7 years ago, it's at 140k right now. All stock.

 

Wait, what relay? As far as I'm aware, the primary engine radiator fan is not controlled electronically at all. It's entirely a mechanical clutch which controls the speed of the fan, which I believe is driven by the output of the water pump. There are no relays or electronics which control it. The electronic fans which are for the condenser on the air conditioning unit (some cars have one, or two fans) is controlled electronically by a relay, yes. But this is not the primary cooling system for the car nor the fan I'm talking about.

Does your car have a conversion replacing this with an electric fan? I doubt it since the rest of the car is stock and unchanged.

http://www.lexls.com/tutorials/cooli...onversion.html

Look behind the radiator, infront of the engine block. There will be a big-ole fan there. It'll be underneath the plastic intake shroud.

As for the fluids - is that the only service which has been done to it? Do you know if any of the fluids have been changed? The transmission, differential and power steering all require service every 4 years. Brakes and coolant every two years. If it's been 7 years since the coolant was changed, it is very very very over-due, and MAY cause cooling problems. It's not guaranteed but you should change it anyway. Take off the radiator cap with the car fully cold and look inside, if it's gummed up you might need a good cleaning of the radiator and might present some cooling issues for your car. If the car is still overheating, in winter, on the highway, it's possible that coolant flow throughout the cooling system is the root problem. Cold be the water pump. Could be bad coolant. Could be a clogged radiator. Could be the thermostat. Need more testing. Inspection of the system and potentially a coolant flush would be the first steps unless there is an obvious problem that presents itself during inspection.

 

I think he might be referring to the front electric fans attached to the condenser, controlled by the relays underneath the driver's side headlight.

I forget the exact details, but they do not always go on with the AC. If I recall correctly, it is both temperature and pressure dependent. So if your engine is running too hot, the electric fans will kick on. Same thing if the pressure in your AC system gets to a certain level, then the pressure switch starts up the fans.

I notice that almost every time I turn on my car, the fans spin momentarily, and then stop (not always). I believe this has to do with what you said where power momentarily goes through the circuit (like when you removed and replaced the relay while power was being supplied).

EDIT: for the tachometer needle, it probably came off the electric motor shaft, used to set its position.

I've made posts about it and there are other posts with similar issues from other owners like these:
https://www.clublexus.com/forums/ls-...l#post10764229

https://www.clublexus.com/forums/ls-...l#post10494953

 

There are instances where we have LS400 with 2 electric fans in front, 1 electric fan in front, and some with no electric fans in front. Op probably has 2 electric fans in front being maybe an option when new, towing package maybe. Anyway, the electric fan on mine kicks on when the sensor at the bottom of the radiator reads 92 degrees Celsius or if I unplug it, there is a pressure switch too. Maybe try unplugging it and see if the fan immediately kick on and if they slow over time, if so, you probably have an grounding problem on that circuit.

The two front fans however by themselves aren't enough to cool the car (at least where I live - tropics). You need a healthy fan clutch / electric radiator fan / hydraulic fan. I've had the experience where my fan clutch failed open, basically the seals failed and let all the silicon inside escape. The only tell tale sign is spinning the fan by hand when cold which should give some resistance, YouTube is your friend here.

Tach and odo, you'll need to send the instrument cluster in.

 

All 1990-1994 USDM LS 400s had 2 front electric condenser fans and the hydraulic, belt driven engine fan behind the radiator. 1990-1994 JDM Celsiors did not have any electric condenser fans and had a hydraulic pump driven engine fan (very similar to the 1st gen SC)

More info on the towing package:
https://www.clublexus.com/forums/ls-...l#post10239221

You are absolutely right that the hydraulic fan and fan clutch are critical to cooling the car properly.

 

ok, $150 leaner and got a working odb1 scanner on, but no codes! meh, only can view datastream

New to the menu, i was running front defroster for a while and then when I stopped, smelled some burning. After a few days started it back up, no prob, but when I hit the AC button, the engine quickly died.
I'm gonna go out on a limb and say A/C compressor? So, i guess that's gonna be my priority being in Southeast Texas real soon. Anyone know any guides on changing them out? Should I opt for a reman or junkyard search? Thanks guys

 

Wow, AC, expensive. I've never changed any part of my AC in my last 2 LS400s cuz it was just too much. I've heard that when you change any part of it that all/most of the parts should also be done.
But anyway, when you turn on the AC and it dies, can you keep it running by giving it gas? If so then the compressor might still be good and could be whatever sensor that's bad which raises the RPMs when the AC is on. I had problems with mine after doing my timing belt cuz I forgot to plug in the tiny grey wire on the front of the compressor. When hitting the AC button, the RPMs went down to about 200 and tried to die. (and the AC button light would blink constantly)

 

I assumed the clutch was running previously, just the compressor wasn't working. Maybe the clutch froze up now? I'll try giving some gas when hitting the A/C button and seeing what that does.
I've found some links that show that I need to get the refrigerant purged prior to pulling the intake lines going into the compressor manifold. I'll see if I can find a local shop that could do it if I get the parts. Looks like there are kits from Rockauto for the compressor and a dryer and some gaskets. Anyone perform this on their own? I don't have a way to capture the refrigerant on my own.