5SFE not maintaining constant temp - Toyota Nation Forum : Toyota Car and Truck Forums

doozergreengrass · 09-20-2010, 05:53 AM

This vehicle just had its radiator and radiator switch replaced. we just bought this camry but already have another camry which had a slightly different problem (ect sensor) so i'm pretty familiar with 5sfe and 3sfe.

I was always led to belive that on Toyotas, the engine temp gauge should remain at half, and this is the case for my other camry at present and also on a corona i had with a 3sfe. is this correct?

With this vehicle, if driven on a highway for a period of say 5 minutes the temp needle drops to very close to the 'C'. However, if it is left idling the fans turn on when it heats up (halfway on temp gauge). but when the fans on my other camry turn off, on this one the fans keep going until gauge is nearly reaching the 'C' before switching off.

Whats causing this if the switch has been replaced? could it also be the ect sensor or is it the thermostat? why would the fans be able to switch on when a certain temp is reached, but not turn off until the engine is far too cool? could it be the incorrect thermo in it? i.e the thermo isn't closing til the temp is alot cooler than normal?

Any help very much appreciated!
Cheers

Jason.MZW20 · 09-20-2010, 07:26 AM

I think you need to have a look at your coolant temperature sender which controls the gauge function. It is separate from the coolant temperature switch and coolant temperature sensor for the ECU.

BamZipPow · 09-20-2010, 07:35 AM

Sounds like you have a defective thermostat...pull it and test it.

Have you attached an ODBII scanner to yer ODBII port to read what the ECT sensor is seeing?

Hajoca · 09-20-2010, 07:40 AM

Have you taken your fan switch out and checked that?

LittleWhiteBubble · 09-20-2010, 07:54 AM

If the switch still turns it on and off, my money would be on the thermostat. It's also the cheapest part to replace, so I would start there first!

Jason.MZW20 · 09-20-2010, 09:47 AM

The fan switches are temperature controlled, so if the fans are running, yet your gauge is reading cold, there's a problem with the gauge sender.

If the sender wire hits a ground, it'll spike up to hot. If it remains open, it'll move down to cold. Sounds a lot like an intermittent connection.

The gauge sender is underneath the water neck. You should see a single wire running to it. I'm not sure if Toyota changed the design or location though.

Do you have heat from the heater? If it's not quite hot, it's most likely the thermostat, but you should still check the gauge function.

BamZipPow · 09-20-2010, 11:26 AM

Oh...could you snap some piccies of yer engine bay and post them up. Maybe you might have some weird things going on in yer engine bay that yer not seeing...

mvftw · 09-20-2010, 11:49 AM

Same problem here...thermostat...replace upper & lower hoses while your at it...

LittleWhiteBubble · 09-20-2010, 12:40 PM

The temp gauge sender has nothing to do with the fans. Whatsoever. It only reads for the gauge.There is a seperate coolant temp sensor that runs to the computer. And then there is a switch on the bottom of the radiator which controls the fans.

So all total there are 3 senders/sensors. If the fans are coming on and off, its pretty guaranteed your fan switch is good. If the gauge gradually moves and doesn't just spike the needle back and forth, the gauge sender is probably good, and if you car is running decent at all and your gas mileage isn't awful, your coolant temp sensor is most likely fine. The thermostat is probably sticking open and not closing when it should. However you can test all of those sensors mentioned.

doozergreengrass · 09-20-2010, 08:01 PM

Thanks very much for replies, will change out the thermo and take it from there

Much appreciated...

doozergreengrass · 09-21-2010, 01:23 AM

Just checked how things were going before. the fans aren't coming on anymore at all now

Checked the heater, its not as hot as it should be.

Leaving the car idling, now the temp gauge starts rising above half, the fans never came on. they did switch on when i turned the air con on though so i the a/c on to bring the engine temp back to normal not wanting to cause any damage.

I'll still replace the thermostat seeing as its cheap n easy but I have a feeling this is not the problem. Will repost as soon as thermo's replaced!

I do not have a meter available to check what the ECT sensor is seeing, but i'm thinking of getting one as they're cheap and handy too...any specific requirements for the meter or one of those universal ones that reads a/c, d/c and (Mah?) or whatever will do?

LittleWhiteBubble · 09-22-2010, 10:47 AM

If the fans aren't coming on at all, the fan switch in the bottom of the radiator on the passenger side is probably bad.

The fans should always come on when ac is turned on. That is controlled by the high pressure switch mounted on the a/c dryer.

The fan switch under the radiator is simple to test. When unplugged the fans should remain on constantly. It is a two wire connection, if you jumper between the two wires the fans should shut off. If they do then the wiring is good and your fan switch is bad. I know that's a little hard to follow, do you see what I mean?

doozergreengrass · 09-23-2010, 04:40 AM

Thannks LittleWhiteBubble. Yes I know what you're talking about, i'll try that and see how it goes. I could do this on my older Corolla 3A but wasn't sure how on this engine.

Interesting they told us they replaced the radiator switch (the car stealer) but I susect they used a 2nd hand one!

Cheers.

doozergreengrass · 09-24-2010, 12:35 AM

Ok. Run a couple of tests on the switch. However, I did not pull the wire out where it plugs into bottom of radiator - I used the extension plug which is connected to the top of the radiator.

When unplugged, the fans came on and run constantly. I jumpered the plug and the fans switched off.

HOWEVER, because I wasn't using the plug at the bottom of the radiator, does it mean that the plug/switch at the BOTTOM of the radiator is faulty?

Cheers!

BTW I can pull the plug at the bottom of the radiator if need be, however it looked like a tight squeeze for my arm with the fun running so close by! But i'm sure if you people tell me its necessary i'll check it.

LittleWhiteBubble · 09-24-2010, 08:32 AM

No that location is fine too. I did the same thing when testing mine. The only reason it would make a difference is if that extension wire were damaged somewhere, but that would mean the fans would be continually running. Since they came on when you unplugged it, and shut off when jumpered, which is normal operation of that "circuit", which may not be the correct terminology, you know the wiring is good. If the wiring is good, the fans should come on when the correct temp is reached, so it only makes sense to me that the switch that screws into that bottom side of the radiator is faulty.