Coolant Thermosensors

tehbrookzorz · Post by **tehbrookzorz** » December 4th, 2007, 9:58 am

Well, the car's been acting up a little. Under load and accelleration, the CEL comes on. I'm getting codes 9 and 69, both coolant thermosensor codes. I made sure my cooant was topped up properly, didn't seem to help. Now realizing that these codes only were coming on during accelleration under load, and that this code turns on the rad fan while it is set, I let the car run, got out and pushed back on the intake manifold. Every time the engine rocks back the rad fan turns on momentarily. Thoughts?

wytbishop · Post by **wytbishop** » December 4th, 2007, 1:59 pm

Without having a chance to study the cooling circuit, I would guess that when you tilt the engine, one of the coolant temp sensors either becomes submerged or ceases to be submerged in coolant and defaults to a state that signals the ECU to turn the fan on.

Something like that, just off the top of my head.

tehbrookzorz · Post by **tehbrookzorz** » December 4th, 2007, 10:41 pm

That was my thought, and maybe it is the case. I tried bleeding the system of air as best I could, topped up, and pulled the two thermosensors nearest the coolant filler neck to make sure they were clean and properly connected. Can anybody tell me where the third thermosensor is off the top of their heads? Where else could I get an airlock that could set these codes?

Oh, and so that you're aware:
"When Code 9 is present, the PCME substitutes fixed calibration values for the various representations of engine coolant temperature used internally. The engine may idle roughly and may be hard to start. Timing and fuel delivery calculations will be skewed somewhat since the coolant temperature will be only an approximation. As well, to safeguard against overheating, the PCME will also activate the cooling fan constantly."
~Engine Controller Malfunction Codes

Note:
Corrected code numbers pulled in original post(17 & 24 are on my other car.... another story).

Whisper · Post by **Whisper** » December 5th, 2007, 3:30 am

If you have 3 thermosensors, which I'm guessing you do, since you're a '92, they should all be on the neck, around the coolant filler cap. One is closest to you - black sensor fan switch, which turns the fans off (possibly the one you're having problems with); another one a bit behind it - green sensor which is the main sensor and reads coolant temperature for various purposes, including turning the fans on; and a tiny black one behind it with a single wire is the sensor for your dash gauge, and doesn't control any part of your engine or cooling system.

I think that should be all.

tehbrookzorz · Post by **tehbrookzorz** » December 5th, 2007, 8:15 pm

I'll try swapping sensors with another car, but it seems like odd behavior for the cel to only illuminate under load & acceleration.

maryus · Post by **maryus** » December 29th, 2007, 11:45 pm

Sorry guys but what is the normal temperature for a KF-ZE engine ? mine stays always slight above the middle. It should not be in the middle ??? thank you

meanwhile i found out , its like that for the most of the ppl , and for a few is 1/2 ..

tehbrookzorz · Post by **tehbrookzorz** » December 30th, 2007, 2:30 pm

Fixed my problem. Turned out to be a broken wire in the wiring harness behind the engine.

alexskull75 · Post by **alexskull75** » February 26th, 2009, 11:29 am

Whisper wrote:If you have 3 thermosensors, which I'm guessing you do, since you're a '92, they should all be on the neck, around the coolant filler cap. One is closest to you - black sensor fan switch, which turns the fans off (possibly the one you're having problems with); another one a bit behind it - green sensor which is the main sensor and reads coolant temperature for various purposes, including turning the fans on; and a tiny black one behind it with a single wire is the sensor for your dash gauge, and doesn't control any part of your engine or cooling system.

I think that should be all.

hi, in your opinion if i have a 94 mx3 wiring and 94 klze with only one sensor for the fan can i install a kl31 ecu? thanks a lot. regards

Daninski · Post by **Daninski** » February 26th, 2009, 1:04 pm

Damn, I just read this and was about to say bad wire when I read your fix. No soup for me.

Glad you got it fixed.

Whisper · Post by **Whisper** » February 28th, 2009, 5:30 am

alexskull75 wrote:
Whisper wrote:If you have 3 thermosensors, which I'm guessing you do, since you're a '92, they should all be on the neck, around the coolant filler cap. One is closest to you - black sensor fan switch, which turns the fans off (possibly the one you're having problems with); another one a bit behind it - green sensor which is the main sensor and reads coolant temperature for various purposes, including turning the fans on; and a tiny black one behind it with a single wire is the sensor for your dash gauge, and doesn't control any part of your engine or cooling system.

I think that should be all.
hi, in your opinion if i have a 94 mx3 wiring and 94 klze with only one sensor for the fan can i install a kl31 ecu? thanks a lot. regards

I'm guessing yes, if it's a 94 ECU as well. Else it'll look for the extra sensor, I think.

kikkalazio · Post by **kikkalazio** » March 2nd, 2009, 12:23 pm

Whisper wrote:
alexskull75 wrote:
Whisper wrote:If you have 3 thermosensors, which I'm guessing you do, since you're a '92, they should all be on the neck, around the coolant filler cap. One is closest to you - black sensor fan switch, which turns the fans off (possibly the one you're having problems with); another one a bit behind it - green sensor which is the main sensor and reads coolant temperature for various purposes, including turning the fans on; and a tiny black one behind it with a single wire is the sensor for your dash gauge, and doesn't control any part of your engine or cooling system.

I think that should be all.
hi, in your opinion if i have a 94 mx3 wiring and 94 klze with only one sensor for the fan can i install a kl31 ecu? thanks a lot. regards[/quot

I'm guessing yes, if it's a 94 ECU as well. Else it'll look for the extra sensor, I think.

thanks , Excuse me for my delayed reply... i was able the find only one sensor for the fans in both the two engine. when i put the kl31 ecu the fans it's on all the time but when i put the k8 ecu the fans work fine. i also supposed that the kl31 ecu it's for the earlier model with 2 sensor for the fan. the problem is that it's near impossible to find the year of the kl31/36 ecu able to manage the single sensor. no one of the seller i was in contact was able to tell me how many sensor their ecu can manage... what i can do now? THANKS AGAIN

alexskull75 · Post by **alexskull75** » March 2nd, 2009, 12:50 pm

don't worry bro for the delay,but please, reply on this thread and not on the private message cause i need the advice of the other guys on this thread who know more than me! anyway was exactly what happened to me with these damned the fans!, maybe the european mx-3 that has only one sensor for the fans control.

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