Lexdesert

Thank you very much for the help, thank you very much indeed, you're all starting to give me some hope. How and where is the ECU that controls the fan located? Can old gearbox oil cause the fan to overspeed, or does the gear box too have a temp sensor in the LS400? You asked if the solenoid is fully open or closed, it does it randomely, it speeds, then after a short while, it returns back to normal speed, when A/C is off. Guys, once again I would like to thank you all for the help offered, am only depending on you all to help me resolve this issue. Chris

I have checked the diagrams, they don't show a complete cooling system for the LS400 UCF21 engine, in the diagrams I don't see the hydraulic oil fan pump, also still I don't see the location of the solenoid valve because it is missing in the diagram, however because of user curiousB, by use of the website he recommended to me, I managed to fix my navigation system, it too had a loose connection, thank you very much, however I haven't yet resolved the speeding fan issue because I can't find the part that controls fan oil flowing speed/pressure! Still need help, however thank you very much guys for the support provided for now, Where I am; am on my own, no Lexus dealership, am only depending on you guys to help me fix this problem.

Hi, I posted an example picture/diagram of what is similar to my fan mechanism, however I have followed the hydraulic pipe line from the steering pump heading towards the fan, it is to compact and squeezed by various parts and pipes, does anyone have a picture of how a solenoid valve looks like or where exactly it is located in LS400, I thought it could be close to the steering pump, but just cant see it. Chris

Thank you very much for your reply, my fan is run by oil from the steering pump, I have attached a diagram which is just like my system, however am told that something that controls the flow speed/oil flow speed is called a Solenoid valve, which is visible in the diagram, and I was told if the solenoid valve has a problem, fluids flow faster, causing the fan to overspeed, however I don't know how this solenoid looks like, and where to locate it in my vehicle, otherwise my problem is a high speeding fan sounding like a jet engine. This solenoid valve, do you know where I can locate it in my car?

Hi, Vehicle is an LS400, it has a hydraulic operated cooling fan, however time comes when my fan speeds extra ordinary, I have changed the fan oil/hydraulic fluids, it never helped, time comes when it speeds out of hand, even when the car engine is in idle. How do I fix this? where I am, i can not access a lexus dealership. The car doesn't have heating problems, just a speeding fan, I have had this vehicle for 3 years, it started doing that last week, someone had mentioned that a part called solenoid valve could be the problem, however I failed to locate this part, he said its the one that controls the speed/pressure of hydraulic flow; causing a stable speed towards the fan, so how do I fix this problem, somebody please help, pleeeeeese!!! Here am on my own!

Hi, Vehicle is an LS400, it has a hydraulic operated cooling fan, however time comes when my fan speeds extra ordinary, I have changed the fan oil/hydraulic fluids, it never helped, time comes when it speeds out of hand, even when the car engine is in idle. How do I fix this? where I am, i can not access a lexus dealership. The car doesn't have heating problems, just a speeding fan, I have had this vehicle for 3 years, it started doing that last week, someone had mentioned that a part called solenoid valve could be the problem, however I failed to locate this part, he said its the one that controls the speed/pressure of hydraulic flow; causing a stable speed towards the fan, so how do I fix this problem, somebody please help, pleeeeeese!!! Here am on my own!