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Discussion Starter #1
My motor overheated a couple of days before, immediately following picking up the car after some collision repairs, and I need some help around diagnosticking the problem from you kind folks...

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- I unfortunately rear-ended someone recently, and because I had been braking to avoid collision, the front-end of the car dipped and so the Prius front bumper didn't participate in the accident. Instead, the hood got crumpled, and damaged the radiator and part of the AC - no contact with motor or engine, and the rest was cosmetic. Happily - No one was hurt and it was hard to see any damage to the other car. So they replaced different panels, as well as the radiator system.

Here's the problem - I drove from the dealer and looked under the hood after I got home, and noticed a few drops of the radiator coolant around the cap. All seals looked tight though, so I thought I would monitor it. Next day drove around town and within 20 minutes or so, noticed the white engine symbol with the words "Check" under it. In the manual, it says to check that there's gas in the tank, and if it persists after a few starts of the car, to go see a mechanic. As I went onto a short stretch of highway to go back home, then I go the red Triangle of Death symbol on the dash and the radiator overheating symbol on the Nav display, but they disappeared as soon as I let up on the gas. It lit up a few more times for a second or two as I waited for my chance to get off the highway. Pulling over I found evidence that more coolant had sprayed in the engine compartment, but my coolant level was still high.

I took it to the dealer again, and they diagnosed it as a vapour lock in the coolant system, as they were able to add about a litre of coolant to the system when flushing it thoroughly.

However, I mentioned to them that when I pulled over shortly after getting the overheating warning that the engine cooling fan was not on, and that I hadn't seen the fan on once since several checks of the radiator since the repairs - and I wondered if this might be part of the problem. They decided to keep the car longer and see if they could test the system on if the fan is working, but since it is all computer-controlled, they weren't sure how to confirm that it works properly.

Here finally is the question: Is there any way to test that the fan works? Running the AC doesn't help with the Prius, to check the fan. Also, maybe the motor is cooled enough to not need the fan by the time one gets off the highway to look undder the hood.

I'll offer any suggestions to the mechanic if you have any...
 

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I take it that you are dealing with a Toyota dealership and if you're not and still with the body shop, get the car to Toyota. They probably won't give you an instant explanation but they do have access to Toyota Prius maintanence. Here you are asking an awfull lot of people to guess and I'm sure you will receive many suggestions. The Prius is in no way similar to any other type car. This does sound like a ECM problem to me but that's only my guess.
 

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Discussion Starter #3
Sorry if that wasn't clear - the collision centre and the toyota dealer are one and the same. Their Prius specialist is the one who doesn't know a test for the fan, or if it would still be on by the time one pulls over after exiting a highway (5-10 minutes).

So I'm asking as you may have observed your cooling fans on at certain times, or if non of you have, then that tells the Prius specialist and myself that this would be normal behaviour.

If you think that the question is too vague then I'm OK with no replies.
 

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FlyingJoe said:
Their Prius specialist is the one who doesn't know a test for the fan...
Why doesn't the "specialist" contact Toyota engineering? Dealers can get the technical information they need from Toyota, or they can request a "real" specialist be sent to solve the problem.
 

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firepa16 is right on. I know you would like to see something tangible here but that ECM monitors coolant temp both for the engine and more importantly the inverter coolant system. Some times my fans remain on for several minutes after engine shut-down and you never know if it's because of engine or the inverter causing the heat. I believe only a Toyota Prius expert can come up with the answer and you probably won't find one at your local dealer but they have the right "phone numbers" for the west coast tech's.
Heck, this engine doesn't even tell you when it is running in several "modes."
 

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They can put the car in inspection mode, where the engine would continuously run. Then let it sit until the coolant temp gets high enough where the fan should run, and see if it does.

Saturns tend to scare people because the fan kicks on at quite a high temperature. Yet, the cooling system is quite efficient at cooling the system down without the fan while driving. So only when at stop-crawl driving on a moderately hot day without AC would the temp go high enough to operate the fan. Other times, the temp is limited by the thermostat to its lowest operating point.
 

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hmm. sounds like a prius my husband is working on. you're not in nc, are you? it says ontario, so i'll assume you're not the guy who owns this particular car.

getting to my point, he's been working on this cooling system for a couple days now and found it's very easy for someone (aka, the last guy who fixed the car) to overlook completely filling the coolant, which would cause the same overheating problem you had after a collision. because he's been researching this a bit, i'll ask him about it tonight and see if he has an answer. i thought you could control that with the scan tool, but i don't remember if it just gives you status or what.

i'll get back to this thread tomorrow.
 

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Discussion Starter #8
Fuses going off...

Thanks for the replies. (And Yes, I'm in Ontario, with probably the first Prius to get front-end work)

It seems that the fuse for the fans keeps burning out, hence the fan not running. And because of that, the overheating must have boiled some coolant and the vapour lock.

They had thought that the vapour lock was the whole problem, and if I hadn't gone back to them about the fan (which I had noted and brought up the first time around when I brought the car back to them with the overheating problem) then I would have kept overheating the car. But they're certainly trying to find the problems once noted.

So thanks for the constructive feedback on the fan and if it would be running.

So now they're looking for the short in the system, as it might be a crimped or cut wire from the accident or from the repairs, unless it's related to the fuse box, then it's bigger problems...

Thanks for your help...
 
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