2G Radiator fans only coming on when I disconnect the temp sensor

[952g63t]

Replaced the temp sensor, same.

Checked the continuity of the clip that connects to the sensor. Both leads are fine.

It's possible that they come on when it gets VERY hot, but I cannot confirm this.

When the car is running, I disconnect the temp sensor clip and they kick on like they would normally.

Could it be my ECU? Or, could it be a relay?

Thanks,

 

[luv2rallye]

In the 2g the ECU turns the fans on based on coolant temp (2 wire sensor), vehicle speed, and AC switch: http://www.dsmtuners.com/forums/attachment.php?attachmentid=86862&d=1219990229. If the coolant temp isn't hot enough it won't turn them on at all. Unplugging the ECT sensor makes the ECU think the temp is cold which is why it turns them on.

 

[yukiz]

Does your car boogs down, like it looses its compression or feels like no ignition timing at all? if it is..
Most likely to be your ECU. I had that symptom last time, and swapped the ECU.
But it is a good thing to check your relay. The relay should be located passenger side, underneath the radio.

 

[luv2rallye]

Since the fans turn on when the temp sensor is disconnected, it can't be a fan relay. It must be the 2 wire temp sensor or the ECU. Most likely the temp sensor since when it's disconnected, the ECU turns the fans on. BTW yukiz is referring to the MFI or fuel pump relays.

 

[952g63t]

Thanks for the help/replies.

I will try and do some logging when I get home this evening and report back with results. Specifically, the running temps and any other information I can gather.

Thanks again,

Does your car boogs down, like it looses its compression or feels like no ignition timing at all? if it is..
Most likely to be your ECU. I had that symptom last time, and swapped the ECU.
But it is a good thing to check your relay. The relay should be located passenger side, underneath the radio.

No noticeable performance issues while the sensor is plugged in. I drove it with the sensor unplugged for about 25 miles, it seemed as though it was pulling timing or something.

Edit:

I was not able to get my logging tool to work. Really didn't matter because I almost overheated on my outing. Fans are not coming on at high temps...

I was cruising at 75 for about 20 minutes then my temp started to shoot up past the symbol, never actually going above it. Temps came back down after I slowed down.

I just dont get it.

 

[952g63t]

I am going to test the voltage readings to the 2 pins. What should I be seeing on each lead? I believe they are both black wires, one has continuous white stripe, and the other is a broken/dashed white stripe.

Only other thing I can think to test is continuity from pin 83 on the ECU, and the ECU itself for leaky caps, etc.

Thanks,

 

[luv2rallye]

Check the sensor first before ECU stuff. What's important (and spec'd) is the sensors resistance. Unplug it and measure resistance across the terminals. Resistance should decrease as temp rises. If it doesn't or the values are way off, replace it. Here's the spec: http://www.dsmtuners.com/forums/mai...couple-minutes-after-start.html#post152374418

 

[952g63t]

I will try that, thank you.

I may wire up my fans to my AC fan power in order to have something until i can figure this out.

 

[luv2rallye]

It's still good to check resistance even though it's new - bad new ones have been known to happen.

If CTS is ok it is possible the ECU is bad (usually leaky caps) so you should probably check that next. However first unplug the CTS and with key on, measure voltage on the harness side connector. It should be 5v. Now plug in the CTS and measure voltage again with key on (may have to plug CTS in with jumpers to get at it).
At 32*F: you should get 3.2-3.8v.
At 68*F: 2.3-2.9v.
At 104*F: 1.3-1.9v.
At 176*F: 0.3-0.9v.
This will help see if at least that part of the ECU is reading correctly. Of course if you always read near zero, you may also have a broken wire or a connector that isn't mating properly.

 

[952g63t]

5.6 - 5.7 at plug with ignition on.

Not able to test with it connected, I need some alligator clips or something.

Going to go ahead and pull my ecu and give it a good once over.

Sensor resistance checked out.

Here are some shots of the ecu, didn't see anything to cause alarm.

This really really sucks.

 

[luv2rallye]

No rotten fish smell on ECU board or components leaking?
This doesn't make sense. You unplug the CTS and fans (both fans at high speed?) go on which says the ECU is working and the CTS is bad. Yet you've replaced (the 2 wire CTS one now - not the 1 wire one) the CTS and measured it's resistance and you say it's in spec. It still sounds like the CTS is bad or perhaps it's connector isn't mating properly. Check it's connector. Then connect the CTS through jumpers to it's connector so you can measure the voltage on it. Compare to spec values I stated in post 9.

 

[952g63t]

No rotten fish smell on ECU board or components leaking?
This doesn't make sense. You unplug the CTS and fans (both fans at high speed?) go on which says the ECU is working and the CTS is bad. Yet you've replaced (the 2 wire CTS one now - not the 1 wire one) the CTS and measured it's resistance and you say it's in spec. It still sounds like the CTS is bad or perhaps it's connector isn't mating properly. Check it's connector. Then connect the CTS through jumpers to it's connector so you can measure the voltage on it. Compare to spec values I stated in post 9.

No fishy smell, no leaky caps.

Fans come on, not sure if its high speed but they sound normal compared to how loud they were before.

Yes, the (2 wire) CTS.

Resistance measured ok, and changed slightly after it warmed up in my hand.

The clip goes on smooth and snaps into place. I can't see why there would be a fault there after testing the leads on the clip and the CTS.

Any other possible points of failure?

Thanks for the help luv2rallye

 

[luv2rallye]

You have the stock fans?
When unplugging the CTS do both fans come on or only one (which one)?

The only other thing I can think of is for the passenger side fan, perhaps the A-11x fan relay (engine fusebox, bottom row, 3rd from right) which controls medium speed, doesn't work. And when you pull the CTS, the ECU turns the fan on using the other relay (A-13x, which is 5th from right). As a test you could try swapping A-11x (bottom row, 3rd from right) with A-09x (bottom row, 1st from right) to see effect. [You may just lose one of the speeds of the drivers side fan when A/C is on by doing this.]

 

[952g63t]

Mishimoto slim fans, wired into the passenger side (main fan) harness feed. The connector for the drivers side (air con feed) is not used currently.

They both come on when I disconnect the CTS.

I tested the top pins for continuity and swapped around all of the relays for the fans when I first noticed this and there was no change. Still could be a bad relay somewhere in there, I need to apply voltage to them to test the switching function still.

Something else I meant to say, although I am not sure if it was because of my wifes phone, my OBD2 tool was not syncing the other night. I am stopping by a buddies house on my way home to borrow another android phone to test my tool.

If OBD2 was dead, could that also be from a malfunctioning ECU?

 

[luv2rallye]

Yes it could (or bad power or ground on the connector). Your slim fans are 2 wire ones, correct? And they are connected in parallel to the passenger side harness with fan positive connected to both the white-black and white-blue wires, and fan negative to both the black and blue-green wires, correct? If so, then sounds like maybe a bad ECU. Can you swap with another ECU?

 

[952g63t]

Yes it could (or bad power or ground on the connector). Your slim fans are 2 wire ones, correct? And they are connected in parallel to the passenger side harness with fan positive connected to both the white-black and white-blue wires, and fan negative to both the black and blue-green wires, correct? If so, then sounds like maybe a bad ECU. Can you swap with another ECU?

I followed a write up to the T when I installed them, but that sounds about right.

I do not have another ECU to test with. Charging up this android phone to see if I can get a temperature reading from the ECU.

EDIT:

No good, couldn't get this phone to connect either.

Really starting to think its my ECU, the power led is lit up on my obd2 scanner.

Next step I guess is to see if the damn OBD2 port is working.

 

[luv2rallye]

Well you could make sure everything from the ECU to the fans is working by first unplugging the ECU. Then with key ON first ground ECU harness pin 20 and then try 21. Fans should come on with either the way you've got them wired.
2G Turbo ECU Pinouts.
http://www.dsmtuners.com/forums/articles-tuning-ecu/246467-how-identify-ecu-pin-numbers.html.

 

[952g63t]

I was sitting here racking my brains over this and was wondering, what if my water pump was failing? If it wasn't circulating enough water through the t-housing, could that trigger a false reading off the CTS? But why would the stock gauge sensor work?

 

[97_4g63t]

Thanks for the help/replies.

I will try and do some logging when I get home this evening and report back with results. Specifically, the running temps and any other information I can gather.

Thanks again,



No noticeable performance issues while the sensor is plugged in. I drove it with the sensor unplugged for about 25 miles, it seemed as though it was pulling timing or something.

Edit:

I was not able to get my logging tool to work. Really didn't matter because I almost overheated on my outing. Fans are not coming on at high temps...

I was cruising at 75 for about 20 minutes then my temp started to shoot up past the symbol, never actually going above it. Temps came back down after I slowed down.

I just dont get it.

going 75 without fans your car shouldn't overheat. That should be plenty of airflow. It never actually overheated on the highway though or it did? Did the fans use to work or did you just barely install them?

 

[952g63t]

going 75 without fans your car shouldn't overheat. That should be plenty of airflow. It never actually overheated on the highway though or it did? Did the fans use to work or did you just barely install them?

While driving towards the end of my trip I noticed the temp go past mid way, and would fluctuate depending on general speed. If I was going fast it would get hot, if I was going slow it would go back to normal op temp.

Fans worked great all last summer and fall.

 

[luv2rallye]

I was sitting here racking my brains over this and was wondering, what if my water pump was failing? If it wasn't circulating enough water through the t-housing, could that trigger a false reading off the CTS? But why would the stock gauge sensor work?

Yes if the CTS wasn't getting hot water on it because faulty water pump or not enough water, that would do it. Make sure the radiator is full and air burbed out: http://www.dsmtuners.com/forums/mai...ation-temperature-problems.html#post153386862.

 

[DSM1G90]

Been reading this post on a similar issue that just flared up with my 1G90 Laser: During a run in town today after getting off the freeway, my CEL was suddenly coming on, stay on for a while, then would go off..and come right back on after a minute or so...then settled down to remain off.

Then, another issue has been surfacing on occasion and happened today with situation above:

My temp gauge was dead center or just below dead center..but once in a blue moon, the gauge would suddenly peak to hot for a few seconds (like if the sending unit wire suddenly touched chassis), then suddenly return back to normal reading.

Prior to my leaving home, I did check coolant level in the radiator and it's right up to the inner lip of the filler area.

Got the vehicle home tonight from work and did the beep test which poked out a code 21 .. Temp Sensor. I had just replaced the Temp Sensor a few months ago due to occasional CEL illumination and eventual hard starting from hot.

My temp sensor, being only a few months old is deciding to go bad on me so soon?

Thx - DSM

 

[952g63t]

Yes if the CTS wasn't getting hot water on it because faulty water pump or not enough water, that would do it. Make sure the radiator is full and air burbed out: http://www.dsmtuners.com/forums/mai...ation-temperature-problems.html#post153386862.

When I was originally troubleshooting the CTS, I had emptied the coolant and completely refilled, bled the system a few times.

ECU swap went in without a problem (thanks again YUPOK). I did have to swap around my plugs and injectors, but it fired right up as usual.

I decided to take a trip to test what happens with the temps and also to fine tune my new Koni's.

I went about 10 miles to a gas station and stopped to pop the hood. It was not overheating but I knew it had reached op temp and they should have been running. I unplugged the CTS plug and they kicked on, made some adjustments to my shocks and babied it back home from there.

So, I'm fairly certain that my ECU is fine.

On the way there I noticed when I was driving that only my top/middle vents were hot, while my foot/mix setting was only warm-ish. Also, while cruising it seemed as though going about 50 ish the engine temp would get warmer, and going 65+ it seemed to cool it down. Idle temp held steady in the middle. The gauge clip to the T-housing was recently redone and again, that sensor is also new so I know the the temp gauge is accurate.

My water pump? I don't understand how that could be faulty, the impeller is attached directly do the belt assembly. Is there a clutch on the impeller shaft? I thought it was a single piece with some gaskets. My thinking is that it is either spinning the impeller or the shaft is completely broken, and if the shaft was broken it would overheat without question.

I have a new Gates pump on hand, is it possible to swap the pump with the long block still in? I need to look that one up.

I know the CTS is good. It has to be something with the connection from the ECU to the CTS clip. But again, I tested the voltage from the clip with the ignition on, it was showing 4.5 volts or something close to that. Maybe its a short that I missed when testing it.

I need to check the CTS clip again. After I cool down first

 

[Lou98GSX]

Do you have a way to monitor your coolant temp . If you do then first make sure you have the coolant topped off . Then start your car and watch the temp . It will go up to 185 and then as the thermostat opens it will come down a little . Next continue to watch the temp rise to 212 then the fans should go on . If the fans don't go on then check that circuit . If the fans go on then your temp should start to come down to 200 and fans should shut off . Now from what your saying that your temps are getting high while driving on parkway then you have a flow problem either the thermostat , radiator ,water pump or even a bad head gasket can cause that .

 

[952g63t]

Tested all of the relays by applying 12v. They all checked out.

To clear up a bit of confusion I have about which sensor does what;

The 2 wire clip & sensor are the ECU/fan controller connection*

The 1 wire clip is only for the gauge*

Is this 100% correct?

And, what exactly should I see at the 2 wire clip with a multimeter w/just the ignition turned on?

I dont know where to go from here.