Bad coolant sensor ?

[Dsmj89]

Here is a pic i took this morning.

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The connector appears to be bridged, and i don't like to run "band-aid" fixes on my car, i like it oem functional, so i was wondering if the coolant temp sensor needs to replaced and that that's why the previous owner bridged the connector and left it disconnected ?
Both fans are always on when the car is started only, and where can i buy this sensor other than mitsu and autozone ?
Thanks for any help.

 

[rarest_90_DsM]

un bridge and hook it up see what happens, its not going to fry anything it may kick a cell though, and make your car run like crap. I just went through this on my 95 tsi some times you play hell finding the right sensor, personally went through about 4 til i got the right one . I have the part number for a 95 tsi if you have problems it should be the same. You can buy them anywhere usually although is better to get a oem new not referb, just try to get a parts guy thats willing to help you not just get you out the door i like federated and napa they know what there talking about usually and iff there in your area

 

[Dsmj89]

I don't want to take the bridge out cause the previous owner told me pretty much that's why he put the bridge, cause the sensor or connector was bad, i forgot which of the 2 he mentioned, but i will try napa.
Thanks for that piece of info rarest.

The car does take about 5 seconds to start, and i heard a bad coolant sensor can also cause this, cause it deals with fuel depending on temp obviously.. Anyone want to chime in on this ?

 

[LiquidX]

A bad coolant temp sensor can cause your car to not start as well. Plug it in and see what's up.

 

[Dsmj89]

Well i bought a new coolant temp sensor and plugged the connector back and the car started right up, after finding out that the old sensor i took out was new after having spoke to the guy who sold the car to me , oh well at least i have piece of mind now.

Moving on to my next issue, the motor fan doesn't turn on at all, if i turn the a/c on then the a/c fan and motor fan both come on as should, otherwise, the motor fan doesn't come on at all and the car would start to want to overheat so i just shut it right off.

I was told it could be a bad relay ? I tried switching my relays around to no success, should i just replace all ? Suggestions/opinions ? I want to get this fixed asap.

* All my wiring is stock and not hacked, it's all original in good condition *

 

[LiquidX]

My guess is a relay as well. What's odd is the fact both fans come on when you press the switch. I was under the impression it was only the driver side fan that came on.

Have you check the fan connectors at all to make sure they are fine and not cut up

 

[Dsmj89]

I checked them both and they look fine but for extra assurance i will re-check them again and report back.

EDIT : Added pics.

A/C Fan switch

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Engine fan switch

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You guys think this corrosion might have something to do wit hthe motor fan ? I doubt it cause if it did then the motor fan wouldn't even come on at all but it does when i turn my ac on.
But as you can see all connectors and harness is all intact.

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Also, i doubt the motor fan would be bad cause if it was it wouldn't even turn on when i turn the a/c on, correct ? Anyone with opinions, or suggestions would be appreciated.

 

[rarest_90_DsM]

Do the fans turn on when you have the jumper wire in the coolant temp sensor harness? if so they probably sold you the wrong coolant temp sensor same thing happend to me. The coolant temp sensor is a thermo resistor it changes resistance values according to temps if you have a coolant temp sensor that operates outside the resistance values your ecu can recognize it will never tell the fans to turn on or keep them on constantly.

 

[Dsmj89]

Well when the coolant temp connector was bridged the fans were on all the time after the car was turned on. And i got the right coolant temp sensor. I'm starting to think it's either bad relays or something bad in the harness, it's starting to piss me off that i'm just about to wire it direct to have the fan running on all the time when the key is set to on.

 

[Chicken Patty]

Jose,

try what I told you earlier, maybe you are not getting any power to the relay or something. Process of elimination my friend

 

[Dsmj89]

Jose,

try what I told you earlier, maybe you are not getting any power to the relay or something. Process of elimination my friend

I will good sir, i'm going to try the first idea you gave me, if that doesn't work i'll see if i can get a test light and from there on forth.
Will keep you updated.

 

[Chicken Patty]

Noted, keep us posted!

 

[rollingstone]

I'm not sure if your 95's cooling system is the same as mine (90 GSX)
but this weekend I experienced the fan problem. I found a sensor at the bottom of the radiator l/h side facing the car. Jumpered the connector and fan worked, plugged back up and turmed on air conditioner both fans worked.
bought new sensor and checked new and old in hot water!!!
new one came on and went off as manual says old one seems to be stuck when checked with an ohm meter. .03ohms
hope this helps

 

[Chicken Patty]

I've never noticed anything on the bottom of the rad for the fans. But I could have looked right at it and not notice.

 

[Dsmj89]

2G's don't have this sensor.
Chicken - I tried switching out 2 known good relays and nothing changed, so next up is checking to see if power is even getting there. Might just take it to an electrician and get it overwith.

 

[LiquidX]

Just keep on going with it for now.

We already know that both fans work. We are just trying to find the issue on why the passenger side main fan isn't coming on when it should but instead is linked with the AC fan.

IIRC the sensor tells the ECU what the temperature is and if the temperature matches what is programed or higher then the fan will come on if you are under 55mph.

As what was said it sounds like a relay to me but that isn't the case. Next would be to see if the relay is receiving power and lastly to see if there is any damage on the ECU itself for the fan controls.

 

[Dsmj89]

Makes perfect sense liquid.

As for the ecu part, my friend (chicken patty ) lent me an eprom ecu he had laying around and i tried it and still the same result, so it has to be electrical-related.

Will keep you updated on this issue.

 

[LiquidX]

Alright well keep the update flowing then.

 

[Chicken Patty]

I think next is to check if relay is getting power, if it is then something funky is going on.

 

[rarest_90_DsM]

Ok this is how this works. The coolant temp sensor is a thermal resistor the hotter it gets the more voltage it lets back to the ecu! If you put your jumper wire in the fans will turn on indicating there is nothing wrong with your wiring or your relays!!!!!!!! with the jumper wire in your car thinks its overheating cause your just looping the voltage back to the ecu with no resistance. Now enter the coolant temp sensor this guy restricts the voltage that goes back to the ecu so you fans dont turn on until the coolant get hot enough to change the resistance value and let more voltage through!!!!!!!!!!

That being said your problem is with your coolant temp sensor you proved it yourself when you bridged the connector if you walked into autozone or advanced auto they probably sold you the wrong coolant temp sensor they list for 95-99 and as the 97 and up run a different resistance value and will cause you fans to never turn on!!!!!!!!!!!!!!!!!!!!!!!!!!!! This is exactly what happened to me and a ton of other people that have changed the coolant temp sensor. my 2cents. You can try going to the dealer and getting the right part. Hope it works out for you..

 

[Chicken Patty]

Really good info in that last post. I would try OEM and see how it goes.

 

[Dsmj89]

I will look into getting an oem coolant temp sensor and see how that goes.

 

[Dsmj89]

Still haven't gotten the money yet to buy a oem sensor, it would suck if i bought it and it doesn't work out.

I did however try my friend's spare oem motor fan and still same problem, at least that is one less thing ruled out that might have been bad.

So it's down to get a oem coolant temp sensor and having the wiring checked for bad current/grounding.

anyone else might have any other ideas ?

 

[Chicken Patty]

Still haven't gotten the money yet to buy a oem sensor, it would suck if i bought it and it doesn't work out.

I did however try my friend's spare oem motor fan and still same problem, at least that is one less thing ruled out that might have been bad.

So it's down to get a oem coolant temp sensor and having the wiring checked for bad current/grounding.

anyone else might have any other ideas ?

You still haven't gotten around to checking for power at the relay haven't you? Get to it!

 

[Dsmj89]

You still haven't gotten around to checking for power at the relay haven't you? Get to it!

No sir i yet to take it to get checked, i will have it checked at the shop while the car get's the full timing belt job done to it.