Need help! Gas engine overheating. Cannot resolve.

30 AMP RDI & CDS fuses you mentioned are in blue circle in the image. Just remove it, and visually check it + use multimeter to test continuity? I had previously checked each and every fuse except for these three since these are joined together. Thanks again @rjparker !

 

I just checked all three fuses ( 2 30A, and 1 10A), and all three checked out. There is continuity. Next I will check fan wiring connectors soon as I figure out how to reach and disconnect these.

 

Techstream is not free but is the Toyota scanner known to be complete. Others in the $500 up range may work as well. In this particular case just operating the ac is enough.

Electrical diagnostics can be tricky from a base understanding level and from accessibility.

Continuity is not checking the circuit. You have to measure voltages. While not likely, both fans could be bad or they could be running but might be hard to hear with the engine rattling.

A one minute test is to open the hood and have a strong light to see the fan blades. Ready the car with the headlights off but use the ev button to keep the engine from running.

In Ready have someone turn the ac on and within a couple of seconds the fans should come on audibly and visually. Turn the ac off and they should shutdown.

The radiator fan power for one fan is accessible between the inverter and fan assembly on the driver's side. It should be possible to back probe that connector in place. I would set the meter for dc volts (in a range to measure 12-15 vdc) and use very fine probe tips, ideally needle probes.

 

One tool a good auto mechanic has are relay test jumpers (relay socket breakout adapters).

• Relay test jumpers are essentially adapters that plug into a relay's socket with the relay plugged in on top of it, providing access to the terminals and circuit wiring through adapter test points.
• These test points allow for easy connection of meter probes, test leads, or an amp clamp for diagnostic testing.
• They come in various kits, often including different relay sizes and types to fit various relay models.

The most common are from Lisle with a set like their Lisle 60660.

60660 Deluxe Relay Test Set | Lisle Corporation

The bottom line is a good shop can make short work of this kind of diagnosis.

 

Thanks so much again for suggestions and educating me! Next chance I get, I will troubleshoot further as you suggested. Yes, I did notice connector for one of the fan accessible. I will get back soon as I have some results.

I was wondering about the JDM engine replacement labor. Do you know how much should I expect to pay for labor if I get a mechanic to replace it?

 

The labor will vary considerably but I would expect $1500 minimum. Ideally a shop that has worked around hybrid systems and knows enough to not be scared of it. Many shops may want to supply the engine and necessary fluids which means a markup on parts.

I might visit the JDM distributor in person and ask for shop recommendations.

 

Do yourself a favor and spend 20 minutes replacing the cheap coils and spark plugs you installed with the originals (if you still have them). You don't have to remove the cowl on the Lexus. While you do this you can check the cylinders for liquid, if you don't have a good way to look in, you could tape a q-tip to a dowel and dip it in each cylinder.

I'm not saying a new engine might not be a good option, but I am saying you are crazy not to spend a few minutes doing basic troubleshooting before purchasing an engine, especially after installing cheap Amazon parts.

 

Thanks @Eddie25 ! Those are some wise words. Yes, I still have original parts except for coolant temp sensor. That one is currently "A-Premium Coolant Temperature Sensor" from amazon, and it'll be difficult to replace ... but appears to be working as I can read temp via Car Scanner app. I will replace everything else next chance I get. I will also perform the "Q-tip" test. Thanks again!

 

"...from amazon, and it'll be difficult to replace ... but appears to be working..."

Anytime you see "from amazon" or "from ebay", you can pretty much KNOW it's the cheap
chinese copies..... And and "from rockauto"....

 

Good Morning @rjparker : This morning I was able to do a bit of testing just like you suggested. I also referred to the service manual that I had downloaded a few months ago. The voltages checked out on all three fuses, relays, as well as to the connector. I tried directly connecting the the driver side fan to the battery. I was measuring voltage while doing that and could see 14.41V, but the fan did not operate. This looks to be the fan motor issue and the fix looks to be replacing both the fans. Please correct me. Thanks again!

 

It looks like a strong indication for replacing that fan, anyway. It may be worth testing the other fan the same way before concluding they are both bad. Also, even for the fan you brought power to, there can still be questions about just how you tested.

When you measured 14.4 V at one terminal of that fan, where was your meter's ground reference? Keep in mind that one of the fans (the one with the green supply wire) does not return directly to ground, but to a relay that switches it either directly to ground (for high-speed operation) or to the supply of the other fan (for low speed). So if that was the fan you were testing, your test might not be telling you what you think, unless you also had energized the "fan no. 2 relay" (or removed it and jumpered the socket positions 3 and 5).

 

@ChapmanF : Thanks so much for guiding me!

I backprobed into +ve terminal of the connector and connected with +ve of battery. Backprobed -Ve terminal of the connector and connected that into Engine body ground. I then connected +ve of multimeter with backprobed +Ve of the connector and -Ve of multimeter with the engine body ground. The multimeter was set to V (DC), I did not disconnect the fan terminal connector (difficult to disconnect, I know I'm being lazy, hence the reason for backprobin). Next test I do I will try to disconnect the driver side fan, and if possible passenger side fan as well. I will then test both the fans directly connected to +ve & -ve of a standalone car battery. Attached is the only photo I have, should've taken more. Thanks again!

 

Overall it seems odd both fans would have failed but since this car is new to you and has never run right, there is no telling what happened to it.

It is possible the plastic fan blade(s) are jammed against their housings. I would verify the blades rotate freely. It may require a wire from the top or access from the bottom. I have seen one jammed blade.

Assuming you tested the accessible connector on top with Blue (+12v) and White/Black (Gnd), that motor does not have a switched ground. It drives the passenger side fan. If you measured with both leads at the connector then your tests seem valid.

No fan after applying power is a pretty good test. You do want to ensure you applied the +12v to the Blue wire or pin and the Gnd to the other wire or pin.

Attached side of connector
Pin with plastic tab receives +12 vdc


As a test, I connected 12vdc to a spare fan assembly and the fans each ran. They can also take a short reverse polarity but I would not try that on an installed assembly.

Changing the fan assembly is no walk in the park, it's very close quarters.



PS. You could do an ohms test on the fixed part of the connector which will read 1.1 to 2.1 ohms. But this is not conclusive if the motor is seized, the blade is jammed or some other internal part has failed.